Annales Agriculturae Fenniae Maatalouden tutkimuskeskuksen aikakauskirja Vol. 19,3-4 al of the gricultural Research Centre Helsinki 1980 Annales Agriculturae Fenniae JULKAISIJA — PUBLISHER Maatalouden tutkimuskeskus Agricultural Research Centre Ilmestyy 4-6 numeroa vuodessa Issued as 4-6 numbers a year ISSN 0570-1538 TOIMITUSKUNTA — EDITORIAL STAFF U. Lallukka, päätoimittaja Editor P. Vogt, toimitussihteeri Co-editor 17. Kossila J. Säkö ALASARJAT SECTIÖNS Agrogeologia -chirnica:L— Maa ja lannoitus ISSN 0358-139X Agricultura — Peltoyiljely ISSN, 0358-1403 Horticultura — PuutarhaYiljety ISSN 0358-1411 Phytopathologia — Kasyitaudit ISSN 0358-142X Animalia nocentia — Tuhoeläimet ISSN 0517-8436 Animalia domestica — Kotieläimet ISSN 0358-1438 JAKELU JA VAIHTO Maatalouden tutkimuskeskus, Kirjasto, 01300 Vantaa 30 DISTRIBUTION AND EXCHANGE Agricultural Research Centre, Library, SF-01300 Vantaa 30 ANNALES AGRICULTURAE FENNIAE, VOL. 19: 187-222 (1980) Seria PHYTOPATHOLOGIA N. 72— Sarja KASVITAUDIT n:o 72 THE OCCURRENCE OF MICROMYCOFLORA IN THE STEM BASE AND ROOTS OF CEREALS IN SOUTHERN FINLAND KAIHO MÄKELÄ and LEENA MÄKI MÄKELÄ, K. & MÄKI, L. The occurrence of micromycoflora in the stem base and roots of cereals in southern Finland. Ann. Agric. Fenn. 19: 187-222. (Agric. Res. Centre, Inst. Pl. Path. SF-01300 Vantaa 30, Finland). About 1035 samples of mature cereals from 119 localities and 1029 shoot samples from 91 localities in southern Finland were examined in moist chamber cultures. Microfungi Were determined in the stem base and roots of five cereals in 1975- 1978. The total numbers of fungal species found were about 130 belonging to 100 genera. Of these the majority (70 genera) belonged to the group Deuteromycotina and of these, 62 genera to the order Hyphomycetes. The group Ascomycotina had 15 genera and Z_ygomycotina 7 genera. In the mature cereal samples the amounts of fungi were nearly 15 % greater than in the shoots. The highest numbers of fungi among the samples were found in wheat and barley, the fewest species in oats. The number of fungal species in individual mature cereal samples showed relatively small variations between the different cereal species, being -on the average 3-6 with the total variation 0-12. In the individual shoot samples the number of fungal species fluctuated more than in the mature plants. Also the annual fluctua- tions in the shoots were greater than in the mature cereals. The majority of the fungi determined were saprophytes. In the mature cereals and in the shoots of winter cereals in autumn an average of 20-30 % of the fungi were parasites. In the spring the proportion of parasites varied from 15 to 40 %. The most common parasitic fungi were'Fusarium culmorum (W. G. Smith) Sacc., F. cwenaceum (Corda ex Fr.) Sacc., Gaeumannomyces graminis (Sacc.) v. Arx et Olivier, Rbizoctonia solani Kiihn and Septoria nodorum Berkeley. The most prevalent saprophytic micromycophlora were Cladosporium-, Alternaria-, Penicillium- and Acremonium-species, Gliocladium roseum Bainier as well as Streptomyces-species. Some of the fungi appeared similarly in ali the cereals. Many of the fungi preferred some particular cereal instead of the others. The age of the cereal stand and the time of sample collection had an effect on the incidence of many of the fungi. There were large differences in their prevalence according to the , year. Index words: Micro‘ flora in the stem base and roots of cereals. INTRODUCTIÖN Interest in the micrornycofiora of cultivated soils has increased greatly during the past two decades in ali parts of the world (BARRON 1968, Domscx and GAMS 1970, SCHIPPERS and GAMS 1979). This increased interest is due in large part to the intensified methods now employed in agriculture as well as to the ever increasing use of monoculture, i.e. the growing of only one type of cereal, with its associated drawbacks. It has therefore be-en considered important to 1 1280021321 187 investigate the species of fungi occurring in cereals, the relationships between the different species as well as the variations in fungal inci- dence and the factors causing these fluctuations (PARKINSON and PEARSON 1965, STETTER and LEROUL 1979). In recent years much emphasis has been given to questions relating to biological control of plant pathogens (BAKER and CooK 1974). In Finland there have been made only a few studies on soil microfungi. Some investigations have been made on the microfungi occurring in forests (FEHER 1933, SVINHUFVUD 1937, MIKOLA and HINTIKKA 1956). Other studies have been carried out on the metabolism of fungi in agricultural soil (VARTIOVAARA 1935). The fungi causing root rot decline of red clover in leys have also been investigated (YLImÄKI 1967). The soil fungi inhabiting cereal fields have been discussed only briefly in connection with studies on foot rot of cereals. In a study on shrivelhead of spring wheat carried out in the years 1946-1953, HARDH (1953) isolated from the eyespots of stembreak-infected plants a total of 16 species belonging to 11 genera. Among these were Cercosporella herpotrichoides Fron, Fusarium avenaceum (Fr.) Sacc. and F. culmorum (W: G. Sm.) Sacc. In the year 1958 the additional species Ophiobolus graminis Sacc. was isolated for the first time in Finland from the stem base of spring wheat (IKÄHEimo 1959). In the years 1962-1964 TOIVIAINEN (1974) investigated the distribution of foot and root rot of cereals on the basis of material comprising different cereal species from 142 farms. The most common fungus was Gaeumannomyces graminis (Sacc.) v. Arx et. Olivier, and also Cercosporella herpotrichoides occasionally appeared in large amounts. Fusarium culmorum was incoun- tered to some extent, while Rhkoctonia sotani occurred only sparsely." TOIVIAINEN (1974) also studied spring wheat and barley material which had becn grown for 10 consccutive years in a monoculture experi- mental area. In this material he isolated from the stem base of the plants a total of 26 species of fungi belonging to 21 genera. The importance of cereal growing in Finland has increased during the past two decades, while the area devoted to grasslands has correspond- ingly decreased. In 1976, for example, cereals comprised 50'% of the total arable land (2 640 million hectares) as contrasted with only 34 °/,, in 1955. Barley (18 % of the arable land area) and oats (22 °/0) grow well throughout the whole country. Rye (1,4 %) is grown in the southern and central parts of the country. The areas devoted to winter wheat (1,4 %) and spring wheat (7 %) are found in southwest and southern Finland. In recent years the area grown to barley has increased whereas wheat and rye have diminished (ANON. 1955, 1976). The purpose of this investigation was to study during the three-year period 1975-1978 the species of microfungi occurring in the stem base and roots of cereals, the quantitative rela- tionships between the different species, and the incidence of these fungi in relation to different cereal species, different times of the growing season as well as different ages of the stands. The location of this study was southern Finland, which is the best area in the country for growing cereals. The original intention of this study was to determine only the occurrence of foot and root rot of cereals. However, it was soon discovered that the fungal material was so interesting and abundant that it was decided to investigate the fungi in their entirety. This decision was made because the knowledge of many of these fungi is so incomplete that one could not with certainty omit any species as being unnecessary. Also included were all those fungi, such as Drechslera and Septoria species as well as Rhynchosporium secalis (Oud.) J. J. Davis, which cause root and base damage to yong shoots. The causal agents of foot and root rots in cereals are discussed in greater detail in a separate paper (MÄKELÄ and PARIKKA 1980). 1 88 1-119,TIM P01.1.1ARAIIITA 1.1.1977 BASLURAH FÖR irrAns. 13.1977 TILASTON POKIAL•11.1,11 1.1 1977 BASIGIITAN KIP STO9115111,1.1.1977 159 209 91. 29 29 NO RWAY 404 SWEDEN USSR Fig. 1. Grigin of the mature cereal samples by localities Fig. 2. Origin of the shoot samples of cereals by localities in Finnisch cultivation zones (I—IV) in 1975-1977. in Finnish cultivation zones (I—IV) in 1976-1978. MATERIAL AND METHODS Region The region of this study comprised mainly the southwestern and southern parts of the country, in the cultivation zones I and II (Figs. 1 and 2). This region makes up 1/3 of the total arable lan.d in Finland (2,6 million hectares). It is especially the production district for bread grains, and in this district continuous cropping (monoculture) of cereals has been practiced since the 1960's. During the years of this investigation the above- mentioned region included over 90 % of the winter wheat area of the country, nearly 80 % of the spring wheat arca, 60 % of the rye and 40'% of both barley and oats (ANON. 1975, 1976, 1977). The soil type in the region of the study is principally clay, especially in Varsinais-Suorni. In Uusimaa fine sand and silt also occur in some places in addition to clay. In South Häme and Satakunta the proportion of clay soils is con- siderably less while silt, fine ,sand and light mineral soils are correspondingly greater (Kmucr 1979). The cereal samples were collected chiefly from clay and silt soils, to some extent also from sandy soils. 189 Weather conditions The weather conditions in this region are the most advantageous in the country. The length of the growing season (+5 °---+5 °C) is 170- 180 days and the average temperature is 12-13 ° C. The precipitation averages 40-80 mm per month and 550-650 mm per year. The latter part of the growing season has normally more tainfall than the early part. The average depth of snow in southern Finland is 20-40 cm. The snow cover protects the overwintering plants from extreme temperature fluctuations and it also retards the freezing of the soil. The length of the growing season, the temperature condi- tions and the precipitation can show considerable annual variations (KoLxxr 1966, SUOMELA 1976). , During the years of this investigation there were large variations in the weather conditions. In addition regional differences also occurred. As a whole 1975 had a warm growing season with low rainfall. The year 1976 was cool with low rainfall, while 1977 was cöol with high rainfall. The amount of rain was greater in the coastal arca than in the interior of the country. The growing season in 1975 was, except for frost nights in May and a cool June, generally warm and long, extending late into the autumn. Long periods of dry weather occurred in Kymen- laakso and South Häme. In contrast there were many local rain showers, especially in the coastal areas. The yields of grain were somewhat smaller than normal. The winter was mild with little snow. In 1976 the growing season was generally cool. Only May and the beginning of August were warm. This season was also somewhat drier than normal, although local rain showers occur- red. The autumn was cool and the growing season came to an early end. The grain yields were record large. The growing season in. 1977 began unfayour- ably. The winter had been long and yery snowy, and the fall-sown cereals suffered from winter damage. Spring sowing was delayed because of rains. With the exception of short warm periods, the summer was cool and rainy. The autumn was warm and wet. The grain yields were low and of poor quality. The winter of 1977-1978 had little snow and the ground frost was deep. Dry winds in the spring of 1978 caused damage to the shoots of the winter cereals. Spring ploughing was delayed as a result of the deep ground frost. The month of May was yery dry, while June had heavy rains. (ANON. 1975, 1976, 1977, 1978). Samples The samples were collected principally from farmers' fields, and to a minor extent from the experimental stations of the Agricultural Re- search Centre. They were gathered every year from the same localities and partly from the same fields. The samples comprised both mature grains at the milky development stage (stage 11, LARGE 1954) and young shoots (stages 1 and 2, LARGE 1954). The mature samples were collected from a total of 1035 fields in 119 localities, and the shoot samples were taken both in the autumn and spring from a total of 1029 fields in 91 localities (Table 1). Ali cereal species were represented in the material. Most abundant were samples of winter and spring wheat and barley, while olts had the fewest samples. The numbers of samples varied from year to year. Despite this, relative proportions of the cereals represented in the total material remained similar, especially in the mature samples. In 1975 and 1976 there were fewer rye samples than usual, while in 1976 the numbers of spring cereal shoots were smaller than usual. Especially numerous were the samples of spring wheat in 1977. In the districts where the samples were gathered, the most common cereal varieties grown during the years of this investigation were Finnish, namely the following: rye: Voima, Toivo and Pekka; winter wheat: Vakka, Nisu 190 Table 1. The number of field samples investigated and localities of collections in 1975-1978. Shoots Mature cereals in autumn Cereals in spring No. of No. of No. of fields localities fields No. of localities No. of fields No. of localities Year in autumn Rye Total Winter wheat Total Spring wheat Total Barley Oats Total Ali the cereals Total 1975 (6) (6) 1976 17 24 1977 27 47 1978 35 77 31 83 32 72 45 94 60 249 1975 48 111 1976 40 99 1977 55 152 1978 - - 84 362 1975 49 95 1976 28 52 1977 46 95 1918 . 83 242 1975 29 35 1976 13 36 1977 24 34 1978 54 105 1975 75- 330 1976 50 282 1977 70 423 1978 - - 119 1 035 26 30 15 21 29 51 48 102 37 84 19 55 33 77 48 216 40 114 24 76 43 128 61 318 1975 1976 1977 1978 • 15 26 27 42 16 55 45 116 35 80 40 83 35 104 49 267 21 47 25 49 9 15 37 111 35 50 34 70 16 40 60 160 14 19 23 32 5 6 40 57 48 212 51 289 48 210 80 711 and Linna; spring wheat: Ruso and Tähti; barley: Pomo, Otra (6-rowed), Karri and Ingrid "(2-rowed); oats: Ryhti, Tiitus, Pendek and Hannes (OFF. STATIST. FINL. AGRIC. 1976). Time of collection The time of the season when the samples were . collected varied considerably from year to year, depending on the weather (Table 2). In 1975 Table 2. Date of collection of samples researched in 1975-1978. Shoot samples Mature cereal samples gathered in autumn Year winter cereals gathered spring cereals gathered in spring in autumn in spring 1975 1976 1977 1978 23. 7.-19. 8. 1. 8.- 9. 9. 10. 8.-22. 9. 9. 10.- 6. 11. 28. 10.-11. 11. 8. 10.- 1. 11. 26. 4.-21. 5. 2. 5.-19. 5. 13. 5.- 5. 6. 6. 6.-22. 6. 5. 6.-25. 6. 15. 6.-25. 6. 191 =Soprophyies RYE WINTER VVHEAT 7 FUNGI No 90- 80- 70- 60- 50- 40- 30 20- 10 ff[11 = Parasites SPRING BARLEY OATS TOTAL VVHEAT 1= 1975 2= 1976 3=1977 T= Total 1 230 the grains ripened early. The collections were begun at the end of July and continued for nearly a month. In 1976 sample gathering was done in August and the first part of September, lasting more than a month. In 1977, due to the very late development, collections were made at the end of August for the winter cereals and as late as the nd of September for the spring cereals, or a total of 11/2 months. The shoot samples of the winter cereals were generally collected in October, but in 1976 this took place in late November and even in the following May. The shoots of spring cereals were usually taken in June. Exceptionally early was the spring of 1975 while 1978 was late. Examination of the samples Ali the samples, both of mature cereals and shoots, were taken from the fields with their roots. In order to facilitate visual examination, the roots were carefully rinsed under running water. The most typical of the mature plants were severed at about 10 cm above the base, and the basal part with its roots was placed in a Petri dish 0 15 cm) on moist filter paper for the purpose of culturing the fungal species. The shoot samples with their roots were put in Petri dishes and their upper leaves were removed. The dishes were initially kept for two weeks at room temperature (+20—+24 °C) followed by two weeks at +10 °C and subsequently another 1-2 weeks at room temperature. During this culture period the fungi were examined a few times with a stereomicroscope. In addition a light microscope was also used for measurements and microphotographs. Slides were prepared with lactic acid, and these aho were measured and photographed. The results are presented by cereal species and by years, and furthermore the totals for ali years are listed separately for mature cereals and for shoots. The incidence of fungi is expressed a:s percentage by number of the examined samples or fields. RESULTS Total numbers of fungi The total numbers of fungi varied depending on the cereal species, the stage of development and the year (Table 3). In the mature cereal samples (Fig. 3) the amounts of fungi were nearly 15 % greater than in the shoots (Fig. 4). The highest numbers of fungi among the mature plants were found in wheat and barley, while among the shoots it was the winter cereals, especially winter wheat, which were most infected. The fewest, species of fungi were encountered in oats. In the winter cereals there -were virtually no differences in numbers of fungal pathogens at the different stages of development. On the other hand, in the spring cereals there were 30-40 % fewer fungal species than in the corresponding mature plants. The Fig. 3. Parasites and saprophytes, total no. per cereal in the stem base and roots of the mature cereals in 1975- 1977. 192 /9 r/ =Saprophytes 7- \\\ _ \\ \\ \\1 \\ \\ \\ \\ \\ \ A \\ \\ \\ 1 2 3 T 1 23T 1 23T N 234 T V 2 34 T OATS TOTAL 1= 1975 2. 1 976 3= 1977 4= 1978 T= Total WINTER VVHEAT FUNGI No 90- RYE WINTER TOTAL RYE VVHEAT 80- 70- 60- 50- 40- 30- 20- 10- 0 SPRING BARLEY VVHEAT = Porasites 234 T 234 T 2 34 T 2 34 T Fig. 4. Parasites and saprophytes, total no. per cereal in the shoot samples in autumn and in spring gathered. bulk of the fungal species were common to ali the different cereals. The total number of fungi averaged 1/5 greater for ali the cereals combined than for each cereal species separately. Con- cerning the shoots the corresponding ratio was over 1/4. Thus the variation in mycoflora be- tween the different cereal species was greater in the shoots than in the mature plants. Similarly there were differences between the years investigated. The most sparse occurrence of fungi in mature plants was in 1976 while in the shoots it was autumn 1977 and spring 1978. The total numbers of fungi in the same cereal considering ali the years combined were 1/3-1/4 greater than considering each individual year. Thus the annual variations were greater in the shoots than in .the mature cereals. Numbers of fungi in the individual samples Although the total numbers of fungi in the different cereals during the experimental period could he very high, the species of fungi in individual samples on the individual fields were rather scanty. The numbers of fungal species in individual mature cereal samples showed relatively small variations between the different cereal species, being on the average 3-6 with the total variation 0-12 (Fig. 5). •The largest numbers of species occurred on wheat, averaging from 3,7 to 6,3 in the different years (range 0-12). The fewest species were found on barley, averaging 3,8- 4,5 (range 0-10). The magnitude of microflora on barley remained about the same from year to year. In the individual shoot samples the number of fungal species fluctuated more than in the mature plants (Fig. 6). The differences between the cereal species were also greater. The most fungal species, averaging 4,6-7,6 (range 0-14), were found in the shoots of winter wheat which were collected in the autumn. These figures were even greater than in the mature winter wheat plants. The fewest species were on oat shoots, averaging 3,2-4,7 (range 0-8). Barley 193 Cn 0 0 en C,1 e, Cr Cr en V) Ta bl e 3. F re qu en cy o f fu ng i o n th e ce re al s am pl es in ve st ig at ed in 1 97 5- 19 7 8 . 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'',, „ s - 00 - ,, tz,„-p..,,........2. ,%,-"',,' ''''..1, -',,,' ', ,'`<-> '', ',!,,'...', "f,'4', --,''- is,? -',-- - -,2,,, ,,t ''-,'''',?±' -'..:.'> -4,, -k'''› ''''''''-''.:',. ...,,_.?,',°°-,•-•> 2, - '4 , , ' , , -,ä- ''' -,,'''; , '•-'' '','', ,,-`',_., .'',:,',.-:,.,'?,,,,',=.' , ':..%t -,' ?,'.`:::, -', '',-,,, .:'.:.s`:-,:.',-,. ''', '',,, o U <,› '7' l o . 1 -.- 0 ,,' ,., '' ''''' 196 8- 01 7- en soc 5- Co" 4- N cn en C, 00 co" ,, c4 <<", 0" <1- co 1 1 - 10- c, N On N ,r) r-- 9- 'RUNG] No 12- 3- 2- I - en C• 04 on N CO Cq « en C'1 On 0 - %rasite, 50prophy4es, - T tal - Range and Meon RYE WINTER SPRING BARLEY OATS WHEAT WHEAT 1= 1975 1976 1977 1 2 3 123 1 2 3 1 2 3 123 r. rr ,-.C'1 0') en CO , Fig. 5. The mean no. and the range no: of parasite and 01 0'.] CO •0 r. Cq Cs1 CO saprophyte in the individual sample of the mature cereals. Cq ci On had nearly as few. The incidence of fungi in en ,n barley shoots remained virtually the same from \ c, Cq year to year just as in the case of the mature N en plants. co" cq There were also differences between the years eq c, of the investigation. The highest number of c, ,n fungal species in mature plants for ali the cereals N N co en N L-- occurred in 1976; it averaged 4,5-6,3 (range .<91 % , dav. w, . z TILASTON PONLAILARTTA 1.1.19" SASSASTAN LOS srAnsr. 1.1.1977 SWEDEN 20. Fig. 1. Origin of the mature cereal samples by localities in Finnish cultivation zones (I—IV) in 1975-1977. Fig. 2. Origin of the seedling samples of cereals by localities in Finnish cultivation zones (1—TV) in 1976- 1978, as well as the meteorological observation stations: 1 Helsinki-Vantaa, 2 Turku, 3 Pori, 4 Jokioinen, 5 Utti. Numbers of cereal samples The cereal samples were collected principally from farmers' fields, and to a minor extent from the experimental stations of the Agricul- tural Research Centre. They were collected from a total of 1035 fields in 119 localities (Table 1). Seedling samples were originated in 1029 fields and in 91 localities (Table 2). Ali cereal species were represented in the material. Most abundant were samples of winter, and spring wheat and barley, while rye had the fewest samples. The numbers of samPles varied from year to year. Despite this, the relative proportions of the cereals represented in the total material remained almost the same. In 1975 and 1976 there were fewer rye samples than usual, in 1976 there were fewer barley samples, and in 1978 the numbers of spring cereal seedlings were less than usual. Especially numerous were the samples of spring wheat in 1977. In the different years most of the samples were taken from the same areas or even from' the same fields. In the districts where the samples were gathered, the most common cereal varieties grown during the years of this study were: rye: Voima, Toivo and Pekka; 227 Table 1. Frequency of the parasitic soil fungi causing foot and root tot diseases of the mature cereal samples investigated in 1975-1977 The samples investigated Parasitic fungi, % of the mature cereal samp'les investigated in the fields Cereal Year 'S N o. o f fie ld s B ip ola ris s or ok in ia na C ol l et ot rir bu m g ra m in ico la Fu sa r iu m a ve na ceu m F . o ul m or um '3 ' F . g ra m in ea ru m F ut ar iu m s pp . G ae um an no m yc es g ra m in is Ps eu do re rc os po re lla be rp ot ri ch oid es R bi zo cto ni a sp p. Se p t or ia n od or um o r,, ,., Rye 1975 (6) (6) 50 67 17 17 17 1976 17 24 29 67 13 13 50 . 1977 27 47 11 38 49 11 30 28 2 Total 1975-77 35 77 Mean 0,6 36 56 12 23 34 3 Winter wheat 1975 31 83 1 1 37 89 7 19 11 2 2 23 1976 32 72 17 57 3 10 14 1 53 4 1977 45 94 1 38 51 2 11 40 1 18 20 Total 1975-77 60 249 Mean 0,4 1 32 66 4 13 23 2 23 17 Spring wheat 1975 48 111 4 1 31 86 5 27 1 1 9 1976 40 99 2 3 6 83 2 13 14 50 6 1977 55 152 5 24 59 4 11 47 0,7 27 10 Total 1975-77 84 362 Mean 2 3 21 74 4 15 24 0,6 25 9 Barley 1975 49 95 19 5 22 70 6 20 3 1 - 1 5 1976 28 52 12 2 10 65 4 19 6 48 2 1977 46 95 13 14 1.3 47 8 31 26 5 Total 1975-77 83 242 Mean 15 8 16 60 9 15 15 0,4 21 5 Jats 1975 29 35 14 20 94 14 29 3 1976 13 36 25 22 69 31 33 1977 24 34 38 21 44 6 9 6 18 Total 1975-77 54 105 Mean 26 21 70 7 23 2 1 17 kll the cereals 1975 75 330 7 4 29 82 7 23 4 2 1 1976 50 282 3 5 13 70 2 16 11 0,4 48 1977 70 423 3 10 26 52 2 10 36 0,5 24 Total 1975-77 119 1 035 Mean 4 6 24 67 5 16 19 1 23 winter wheat: Vakka, Nisu and Linna; spring wheat: Ruso and Tähti; 6-rowed barley: Pomo and Otra; and 2-rowed barley: Karri and Ingrid. Of the oat varieties, the most commonly grown were Ryhti, Tiitus and Pendek (OFF. STATIST. FINL., AGRIC. 1976). Time of collection of the samples The cereal samples were collected at the milky development stage (stage 11, LARGE 1954). The time of the season when the samples were collected varied considerably from year to year, 228 Table. 2. Frequency of the parasitic soil fungi causing foot and root rot diseases of the shoot samples, investigated in 1975-1978. Cereal The amples inves igated Parasitic fungi, % of the shoot samples investigated in the fields N o. o f lo ca lit ic s N o. o f fi e l ds B ip ola ri s so ro ki ni an a C oll et ot r i ch um gr an dn ico la Fu sa riu m ar en ac eu m '-. 2 Year F . g ra m in ea ru m Fu sa riu m s pp . G ae um an tio ns yc es gr am in ii ty• n ', 5 Ps eu do ce rc os po re lla be rp ot rk bo id es 't`' ,r, 'C' 2 p, Gaihered in aulumn Rye 1975 26 30 3 33 70 33 13 1976 15 21 29 48 5 24 43 1977 29 51 26 67 4 16 Total 1975-77 48 102 Mean 1 28, 64 3 23 9 4 Winter wheat 1975 37 84 2 2 31 85 2 46 8 44 1976 19 55 11 55 2 26 2 46 29 1977 33 77 1 22 58 18 3 16 Total 1975-77 48 216 Mean 1 1 23 68 1 31 4 13 30 The both cereals 1975 40 114 2 2 32 81 2 38 6 36 1976 24 76 16 53 3 25 1 45 21 1977 43 128 1 23 62 2 17 2 9 Total 1975-77 61 318 Mean 1 0,6 25 66 2 26 2 11 22 Galbered in spring Rye 1976 15 16 13 69 38 ' 6 1977 26 55 2 6 40 2 47 12 16 2 1978 27 45 2 9 18 2 2 36 2 4 Total 1976-78 42 116 Mean 1 1 8 35 2 23 29 9 3 Winter wheat 1976 35 80 25 78 54 1 1 11 1977 40 83 2 11 59 11 24 15 29 1978 35 104 13 18 2 50 1 51 Total 1976-78 49 267 Mean 0,7 16 49 1 3 43 0,4 5 32 Spring wheat 1976 21 47 2 23 66 19 30 1977 25 49 4 92 2 14 6 2 1978 9 15 20 93 20 Total 1976-78 37 111 Mean 1 14 81 1 17 15 1 Barley 1976 35 50 2 14 76 18 24 1977 34 70 1 3 64 1 27 9 1978 16 40 5 5 68 30 Total 1976-78 60 160 Mean 3 7 74 0,6 24 , 11 Oats 1976 14 19 ' 5 53 37 32 1977 23 32 9 75 3 22 9 1978 5 6 50 50 50 Total 1976-78 40 57 Mean 12 65 2 30 16 Ali the cereals ' 1976 48 116 1 19 72 35 16 ' 1977 51 151 0,3 1 7 67 1 12 22 11 1978 48 61 1 12 34 1 0,5 41 1 Total 1976-78 80 711 Mean 1 0,4 12 59 1 5 31 10 ' 229 depending on the weather. In 1975 the grains ripened early, both winter and spring cereals at almost the same time. The collections were begun at the end of July and continued for nearly a month (23. 7.-19. 8.). In 1976 the sample gathering was done in August and the first part of September, lasting more than a month (1. 8.-9. 9.). The autumn of 1977 was especially late. The samples of winter cereals were collected mainly in August (10. 8.-8. 9.) and those of spring cereals for nearly 1 months, until the end of September (10. 8.-22. 9.). The seedling samples (stages 1 and 2, LARGE 1954) of winter cereals were generally gathered in October, but in 1976 this took place late in November and even in the following May. The seedlings of spring cereals were usually collected in June. Exceptionally early was the spring of 1975 while 1978 was late. Experimental Methods The mature grain and seedling samples were taken from the fields with their roots. Twenty plants from each field were analyzed. In order to facilitate visual examination the roots were carefully rinsed under running water. For each mature sample an evaluation was made of the quality of the stem base (length 10 cm), the roots and the head. For the seedlings (1-4-leaf stage) the stem base and leaves were evaluated. The s.tem bases were classified into five cate- gories: 1. pale, 2. mottled, 3. brown, 4. spotted, 5. black. The pale stems showed no colour at ali. The mottled stems had indefinite streaking and spotting. In the spotted stems there were one or more distinct spots. In the brown and black stems the colour was uniform. The roots of the plants were divided into three categories: 1. .healthy, 2. moderate, 3. diseased. The healthy roots were pale and dense, whereas the diseased ones were discoloured, grey and sparse, and the moderate roots were intermediate in their symptoms. The heads were classified into healthy and shrivelled. Detailed analyses of the individual cereal samples were performed in the years 1976 and 1977. Determination of the causal agents The most typical of the mature samples were severed at about 10 cm above the base, rinsed under running water, and the basal part with its roots was placed in a Petri dish ( 0 15 cm) on moist fllter paper for the purpose of culturing and identifying the fungal species. In the diseased samples the heads were analyzed in the same way. The dishes were initially kerit for two weeks at room temperature (+20—+24 °C) followed by two weeks at +10 °C and subsequently another 1-2 weeks at room temperature. The culture period was thus more than a month. During this period the fungi were examined a few times with a stereomicroscope. In addition most of the dishes were also studied with a light micro- scope for measurements and microphotographs. Slides were prepared with lactic acid, and these also were measured and photographed. The results are presented by cereal species and by years, as well as totals for ali the trial years. The incidence of fungi is expre'ssed as percentage by number of the examined samples or fields. Weather conditions The weather conditions during the trial years. fluctuated greatly. There were also considerable differences between the localities. The meteoro- logical observations were taken from five stations of the Finnish Meteorological Service, namely Helsinki-Vantaa airport (Uusimaa), Turku (Var- sinais-Suomi), Pori (Satakunta), Jokioinen (South Häme) and1 Utti (Kymenlaakso) (Fig. 2) (METEoRoL. YEARB. FINL. 1975, 1976, 1977, 1978). The results are presented graphically from Helsinki, Turku and Jokioinen (Fig. 3). The summer 1974 was rainy. The following winter 1974-1975 was mild with little snow. 230 mm HELSINKI 1 00- 1975 1976 1977 25 2 15 1 5 0- 90- 80- 70- 60- 50- 40- 1976 JOKIOINEN mm 100- 1975 1977 ° C 25- 20- 15- 10- 5- 0- 90- 80- 70- 60- 50- 40- 30- 20- I 10- rL 0 vt VII VIII ix 11 r UI Jr VI 'VII VIII x x V VI VII V II T IX X ' M TURKU 100- 1975 1976 1977 90- 80_ 70- 60- 50- 4 0- 30-, 20- 10- v rj f Uifl V VI VII VIII IX 0 VI VI VI X VI VII VII 11' 1,, X-1 30- 20- rff F r I I U I 1T V VII VIII 11 17 10- vrT V VI 0 V VII VIII X If VI VI v x Fig. 3. Temperature °C ( mean, normal va ue in 1931-1960) and precipitation mm (ruled columns during the trial period, unruled columns normal value in 1931-1960) in the decade during the trial periods in 1975-1977 at Helsinki, Turku and Jokioinen. 6 1280021321 231 Growing season 1975. Owing to warm weather early in the spring, the winter cereal seedlings began their growth rapidly. Likewise the spring cereals were sown early with subse- quent good germination. Severe frost in late May and early June caused heavy damage, especially to rye. The growing season was, with the exception of a cool July, generally warm and dry. Long dry periods occurred particularly in Kymenlaakso and South Häme. On the other hand there were many local rain showers, especially in western Finland. The autumn was also warm and dry. In the southern parts of the country the winter 1975-1976 was mild with little snow. Growing season 1976. The ground frost was deep and it melted slowly. Cold, dry condi- tions retarded plant growth. Seedlings of winter cereals, however, survived the winter quite well. Spring cereals were sown later than usual but the germination was good. The growing season as a whole was cool and somewhat drier than normal. Only May and the beginning of August were warm. Normal precipitation occurred only in June. Local showers in July increased the total rainfall considerably. Also in the beginning of August abundant rains fell in e.g. Helsinki, Pori and Utti. Harvest took place late, and the autumn sowings were likewise late. The autumn was cool and the growing season ended early. Growing season 1977. Seedlings of winter cereals, especially rye, suffered from winter frost damage. The winter 1976-1977 was long with a deep snow cover and only little ground frost. Spring sowings took place 1-2 weeks later than normal. This was due to heavy rains which fell in the middle of May, principally in southwest Finland. In general the growing season was cool and rainy, with the exception of short warm periods in the beginning of June, August and September. The heaviest precipita- tion occurred at Turku, whereas the rainfall was close to normal at Utti and Jokioinen. In late autumn the weather was warm and rainy. The winter 1977-1978 had little snow and the ground froze to a great depth, especially in southwest Finland. In late winter and early spring 1978 the weather was sunny and windy. As a result, the snow evaporated directly into the air and the plants were damaged by the drying wind and the ground frost. May was extremely dry, virtually without rain at ali. Because of the deep ground frost, spring sowings were carried out late, particularly in southwest Finland. June was very cool and rainy. As regards weather conditions, the growing seasons 1975 and 1976 were favourable, even though they were somewhat drier than normal. The least rainfall occurred in 1975 in Kymen- laakso and South Häme. This season was also quite dry in Varsinais-Suomi. The cool weather prevented excessive evaporation, so that the plants did not suffer from the drought. The growing season 1977, on the other hand, was unfavourable since it was both rainy and cool. RESULTS Injures in mature grain samples At the time of the autumn harvest, the major part of the stem bases and roots of the grain samples were damaged in one way or another (Fig. 4). The degree of injury in the stem bases and roots was usually correlated, so that if the plant had many pale-coloured stems, then the roots were healthy; and the reverse was also true. In winter cereals there was generally a cor- relation between pale (= healthy) stems and a good root system. In contrast, the spring cereals had more pale stems than good roots. In 1976 the numbers of pale stems in ali the cereal species were double those found in the year 1977. In the roots no corresponding differences occurred with the exception f oats. In oats the amounts of pale stems and good roots were considerably 232 0 0 Damage A 100- 90- 80- 70- 60- _. 50- 0 0 40 30 - 20.. 10:- 0 Roots 30- CI Healthy 40- Moderate Disease 70- 80- 90- 100_. 2 2 12 2 12 B C Fig. 4. Different lesions (%) in basal parts of stem and roots of the mature cereal samples researched in 1976 (1) and 1977 (2). (A = rye, B = winter wheat, C = spring wheat, D = barley, E = oats). greater (30-80 %) than in the other cereals (10-35 %). Exceptionally low were the figures for barley and winter wheat (7-23 %). Moderately damaged, mottled stems as well as moderately damaged roots Occurred in almost equal numbers in both trial years and in ali the cereal species, amounting to about 1/2 of the plants examined. Only in oats was the incidence of mottled stems considerably greater in 1977 than in 1976. Obviously discoloured stem bases included the three categories brown, black and spotted. Their total numbers corresponded generally with the poor roots in ali the cereals. The highest figures for this group were found in wheat and barley (35-45 %) and the lowest for oats (below 10 %). In rye this group repre- sented about 20-30 % of the plants. In both of the trial years the numbers of brown-stemmed samples were •approximately the same, 15 % in rye, 20 % in wheat and 5 % in oats. Barley diverged from these other cereals. In 1977 more than 1/3 of the barley samples had brown stem bases, which was nearly twice as many as in 1976. Black-stemmed plants were very scarce in 1976, but in 1977 their numbers had increased many-fold, particularly in spring wheat but also in winter wheat and barley. In rye they amounted to only a few percent and were virtually non-existent in oats. Spotted stem bases were likewise sparse in occurrence. Their maximum numbers were found in winter cereals in 1977, in spring cereals in 1976. The highest numbers occurred in wheat and barley, while oats had vittually no spotted stems at ali. There were distinct differences in the plant injuries between the two trial years. In 1977 there were clearly fewer pale stem bases and healthy roots than in 1976. In 1977 brown- stemmed barley and mottled-stemmed oats were much more numerous than in 1976. Simi- larly black-stemmed satnples were more abun- dant in 1977 than in 1976, and this was most evident in 'wheat and barley. Injuries in seedlings The major part of the seedlings, both those collected in the autumn and in the spring, were healthy (Fig. 5). In this respect they differed clearly from the mature grain samples (Fig. 4). The rye and winter wheat samples gathered in the autumn had very similar amounts of injuries in the same years. Likewise the stems and leaves had similar injuries. The difference occurred only in the amounts of damage to the roots. In both cereal species such root damage was greater in the autumn 1977 than in 1976. The injuries in Winter cereal seedlings, partic- ularly in the leaves, were considerably greater in the spring-collected samples (av. 45-60 %) than in the autumn-collected samples (av. 10- - 10_ 20- 50- 60- 2 B C 1 2 12 12 12 7 7 Roots EI Pale t7J Mottled lIB Brown Spotted Black 233 Damage % 100- 90 80- 70- 60- 0 50- 2 40 30- 20- 10_ 0 A 12 1 B 12 1976 C 12 D 12 E 12 A 12 12 1977 BCDE I 2 12 12 12 1 ABCD 1 2 1978 12 12 1E2 1976 AB I 2 12 1977 A 12 S 12 -90 -80 -70 -60 -50 40. 30 20 19 10- 20- 30 40 1,2 50 8 ao 70- 80 90-- 100- % 3 3 P C 3 3 D 3 3 3 ABCDE 3 A 3 3 3 BCD 3 fil 3 A 3 3 B A 3 B 10 20 30 40 50 -60 -70 -80 -90 -100 1976 1977 197 8 1976 1977 Fig. 5. Different lesions (%) in basal parts of stern (1), leaves (2) and roots (3) of the seedling samples xesearched in 1976-1978. (A = rye, B = winter wheat, C spring wheat, D = barley, E = oats) (cf. Fig. 4). 15 cy0). Likewise the stems and roots showed more damage in the spring than in the autumn. Especially severe damage occurred in the roots in the spring 1977. The seedlings of spring cereals had distinctly less injury than those of winter cereals. Con- cerning the different cereal species, oat seedlings were healthier than the others. Numbers of shoots The numbers of shoots per plant varied in the different cereal species and trial years (Table 3). The highest numbers of shoots were in rye, averaging 2,3 and 1,8 in the two trial years 1976 and 1977. The fewest occurred in spring wheat, with corresponding figures of 1,3 and 1,3. In winter cereals, especially rye, the number of shoots was greater in 1976 than in 1977. Shrivelled heads The incidence of shrivelled heads fluctuated widely according to the different cereal species and years (Tables 3 and 4). In 1976 there were considerably more shrivelled heads than in 1977.. Only in oats was the relation reversed. The most shrivelled heads occurred in winter wheat, the fewest in oats and barley. The black-stemmed shoots had more shrivelled heads than the other categories of samples. In 1975 wheat plants were observed with violet-shaded, metallic-appearing discolouration in the heads, of which some were shrivelled. This occurred in 1/3 of the winter wheat fields and over of the spring wheat fields. In other years this phenomenon was not observed. It was apparently related to the unusually dry and warm weather in that year. Fungi causing root and foot rot diseases In the trial years 1975-1978 about 20 fungal species known to cause root and foot rot diseases were found in the cereal samples. This number represents about 20-30 % of ali the 130 fungal species found in mature cereals and seedlings of winter cereals, and 15-40 % of the total fungi in spring-collected seedlings. 234 Table 3. Number of shoots per individual plant and extent of the shrivelled ears, % of the mature cereal samples investigated in 1976 and 1977. Cereal Year of Number of fields investigated Number shoots investigated Number of shoots per individual plant Shrivelled ears % of shoots investigated mean range mean range Rye 1976 24 389 2,3 1-9 12,2 0-17 1977 47 960 1,8 1-10 4,0 0-21 Total 1976-1977 71 1 349 ' Mean 1,9 6,8 Winter wheat 1976 72 1 340 1,6 1-7 19,7 0-55 - 1977 94 1 840 1,5 1-7 5,9 0-56 Total 1976-1977 166 3 180 Mean 1,5 12,0 Spring wheat 1976 99 - 1 960 1,3 1-6 7,7 0-25 , 1977 152 2 900 1,3 1-6 5,9 0-60 Total 1976-1977 251 4 860 Mean 1,3 6,6 Barley 1976 52 860 1,8 1-8 3,4 0-10 1977 95 1 820 1,8 1-10 1,8 0-14 Total 1976-1977 147 2 680 Mean 1,8 2,3 Oats 1976 36 620 1,5 1-5 1,9 0-16 1977 34 680 1,4 , 1-5 3,2 0-17 Total 1976-1977 70 1 300 Mean 1,4 2,8 All the cereals 1976 283 5 169 1,7 1-9 9,0 0-55 1977 422 8 200 1,6 1-10 4,2 0-60 Total 1976-1977 705 13 369 1-10 0-60 Mean 1,7 6,1 The majority of the fungi were saprophytes (MÄKELÄ and MÄKI 1980). The present study describes the twelve most important fungal species causing root and foot rot (Table 1). Root and foot rot fungi occurred mostly in barley and wheat and least in oats. There were also differences between the trial years, with most fungi in 1976 and fewest in 1977. More fungi were found in mature grain samples and seedlings of winter cereals than in seedlings of spring cereals. The most prevalent of the root and foot rot fungi were Fusarium culmorum, F. avenaceurn, Gaeumannomyces graminis, Rhkoctonia solani and Septoria nodorum. Only small amounts of Pseudo- cercosporella herpotrichoides were found. Fusarium species. During the trial years Fusarium species occurred commonly in ali the cereals and in nearly ali of the samples. More than a dozen of them were determined, of which the most common were Fusarium avenaceum and F. culmorum. Appearing infrequently were F. graminearum, F. poae and F. semitectunr. Only sporadically were the following found: F. acuminatum, F. arthrosporioides, F. coeruleum, F. tricinctum and F. oxisporum. F. nivale occurred only in the seedlings of winter cereals in the spring. There were virtually no differences between the cereal species in regard to the incidence of Fusarium species. In contrast, there were dif- ferences between the years. In 1975 Fusarium 235 Table 4. Frequency of the parasitic soil fungi in the ears of the mature cereal samples (cf. Table 1). Cereal Year inves- Parasitic fungi, % in the ears B ip o la ri s so ro ki ni an a No. of C oll e S ot ri eb um gr am in ico la tigate d Pa sa sia '', av en ac eu m i: te; , .:•=. ,4 ., Fu sa ri um s pp . R bi od on ia s pp . Se pl or M n od nr um Rye 1975 _ _ _ _ _ _ , _ 1976 15 27 13 40 7 1977 46 57 26 2 35 2 4 Total 1975-77 61 Mean 49, 23 1,7 36 3 3 Winter wheat 1975 44 2 11 27 20 1976 61 3 21 2 21 2 3 1977 92 1 2 9 23 24 1 34 Total 1975-77 197 Mean 1 1,7 8 23 0,5 22 1 17 Spring wheat 1975 38 18 40 3 29 1976 75 7 69 12 1 1 1977 152 1 23 40 2 29 1 22 Total 1975-77 265 Mean 0,7 18 48 2 24 1 13 Barley 1975 16 25 19 19. 1976 29 3 3 28 3 35 1977 94 15 18 21 6 37 13 Total 1975-77 139 Mean 11 16 22 5 35 Oats 1975 — — — — — — — — — — 1976 9 33 22 1977 34 6 9 18 18 3 21 Total 1975-77 43 Mean 5 7 14 21 2 21 Ali the cereal 1975 98 1 16 31 1 23 1976 189 0,5 6 41 1 21 2 2 1977 418 5 1 22 29 2 0,2 30 1 19 Total 1975-77 705 Mean 3 0,6 17 32 2 0,1 27 1 12 was 1110rC common and in 1977 less common than in the other years. An exception to the other Fusarium species was F. nivale, which appeared abundantly only in the spring 1977 in rye seedlings (Table 2). Fusarium culmorum (W. G. Smith) Sacc. Fusarium culmorum was very common in ali the cereals and at ali stages of growth. In the mature samples it was found at 101 localities. There were no appreciable differences between the different localities. On the other hand, the years showed considerable differences. This fungus was most prevalent in the year 1975 (Table 1, Fig. 6). The stem bases which were infected with Fusarium culmorum were, up to their first node, uniform brown in colour or were mottled or spotted brownish in varying degrees (Fig. 7, Plate III). Pale red discolouration alsb could be seen. Under moist conditions a reddish mycelium developed between the leaf sheath and the stem, and in addition sprodochia 236 Fungi % 100- 90- 80- 70- 60- 50- 40- 30- 20- 10- 0 EI = Fusarium culmorum =Gaeurnannornyces gransinis n = Rhizoctonia SOIOrj 19 76 Ii Barley Oats Rye Winter wheat = Septoria nodorurn 1977 Winter Spring wheat wheat • 13' a tie Y Oats 7 wheat Barley Oats 1975 1 1 11 11 11 11 1[ 11 11 1 Rre Winter wheat wSilireirg Fig. 6. Frequency (%) of some most important parasitic fungi on mature cereal samples researched in the different growing season 1975, 1976 and 1977. appeared in the roots and stems, especially at the nodes. The infected stem bases were more brittle than healthy ones and thus were easily broken. This was especially clear in the late summer and autumn 1975 when diseased plants were abundant and the weather at ripening time was dry for along period. The roots of plants infected by F. culmorum were coloured brown in varying degrees and were to some extent weakened (Fig. 7, Plate III). In seedlings the disease was manifested as a darkening and rotting of the stem bases and roots. Oats dif- fered from the other cereals in the fact that even though the fungus occurred commonly, the disease symptoms did not appear. In comparing the incidence of dark stem bases in the cereal samples with the amounts of Fusarium culmorum determined in the fungal cultures, it was ascertained that they did not always correspond with one another. In the years 1975 and 1976, however, there was a positive correlation, whereas in 1977 no such correlation was found. Fusarium avenaceum (Corda ex Fr.) Sacc. Fusarium avenaceum was considerable less com- mon than F. culmorum; these two fungi often occurred together. The greatest amounts of this fungus were found in mature plants of winter cereals, and the least in the seedlings collected in the spring. Fusarium graminearum Schwabe, perfect stage Gibberella eae (Schw.) Petch occurred rarely. The perfect stage was encountered only in mature cereals. These fungi were relatively more common in oats in 1975. Oat plants infected by Gibberella eae occasionally had roots which were poorly developed, a dark stem base and shrivelled heads. In the tissue of the stem bases the fungus produced black ascocarps and from them exuded great masses of salmon-coloured ascospores (Plate III). Fusarium nivale (Fr.) Ces. Fusarium nivale occurred commonly in rye seedlings only in the spring 1977. At this same time the fungus was much less prevalent in winter wheat. The injuries to the seedlings varied widely according to the intensity of infection. If the leaves are damaged, the plant usually recovers, but root damage results in stunted growth or death of the plant with a subsequent sparse stand (Fig. 8). 237 Fig. 7. A—F: Diseased roots and basal parts of stem of cereals. A, B, C: Gaeumannomyces graminis. D, E, F: Fusarium culmorum. G, H: Rhizoctonia sotani. A: on rye. B, D, E, F, H: on spring wheat. C: on barley. A: Brown hyphae on culm. B: Leaf sheath pulled aside with necks of numerous perithecia breaking through the surface of leaf sheath. D, F: Brown coloured basal parts of stem. E: Multi-coloured basal parts of stem. G: Young white sclerotia and mature brown sclerotia of R. sotani on roots. Material: A: U. Siuntio 12. 8. 1977. B: Eli. Iitti 6. 9. 1977. C: U. Tuusula 7. 9. 1977. D: U. Anjala 17. 8. 1976. E, G: EH. Pälkäne 14. 8. 1976. F: V. Mietoinen 8. 8. 1975. H: U. Elimäki 17. 8. 1976. 238 Fig. 8. A—H: Diseases of seedlings. A, B, C: Gaeumannornyces graminis. D, E, F: Septoria nodorum. G, H: Fusarium nivale. A, B, D: on winter wheat. C: on barley. E. F: on spring wheat. G, H: on rye. A, B, C: Dead and black parts of roots infected by G. graminis. D: Brown spots on leaves and sheath. E, F, H: Dying seedling, G: Diseased seedling with sporodochia of F. niva/e. Materia: A: V. Kiikala 19. 10. 1977. B: EH. Hattula 7. 5. 1977. C: Ypäjä 22. 6. 1976. D: U. Artjärvi 11. 11. 1976. E, F: EH. Pälkäne 20. 6. 1978. G: U. Vihti 9. 5. 1977. H: EH. Somero 19. 5. 1977. 7 1280021321 239 TIUSTON PORJAKARTTA I 1.1977 BRUM,. FOR 51,115,11, I 1 1871 SWEDEN Gaernannomy s graminis Bipolaris tarokiniana NORWAY 0 Winter Wheat 0 Spring Wheat Barley 63' Fig. 9. The occurrence of Gaeumannomyces graminis and Bipolaris sorokiniana on the mature cereals by localities in 1975-1977. Gaeumannomyces graminis (Sacc.) v. Arx et Olivier. In the years 1975-1978 Gaeumanno- myces graminis was found in cereals at 64 localities (Fig. 9). There were large variations in the frequency of the fungus depending on the cereal species, the trial year and the region. The fungus was most common in wheat, and quite common in rye, whereas it was rare in barley and vir- tually not found at ali in oats (Table 1). In 1977 this fungus was considerably more prevalent than in the two previous years (Fig. 6). Geo- graphically it was more common in Varsinais- Suomi and Satakunta than in Uusimaa and South Häme (Fig. 10). Fig. 10. Frequency (%) of Gaeumannomyces graminis on mature wheat and barley samples researched in 1967 at the different districts. The disease caused by Gaeumannomyces gra- minis, take-ali, was manifested in different ways in the cereal stands. On some fields the disease appeared as weak areas in the stand consisting of low-growing, stunted, dark-coloured plants with many shrivelled heads. In most infected fields, however, take-all occurred scattered throughout the whole stand as individual diseased plants. Such plants grew poorly and usually had shrivelled heads. At first the heads were pale-coloured and could easily be dis- tinguished from the still immature, green healthy plants. Later the heads became dark owing to masses of the sarpophytic fungus growing on the surface. Also these stands had a spotty, variegated appearance. Excessive moisture fa- voured the fungus, and consequently it was found in abundance in low, moist areas of the field. The roots of take-all deseased plants had a uniformly dark or entirely black colour and 240 were poorly developed, sparse and fragile. When the plants were removed from the ground the roots often broke off. The mycelium of Gaeman- ~yes graminis growing on the root surface caused the roots to become thick, and soil particles were tightly attached to the surface (Fig. 7, Plates I and II). Ascocarps could also develop in the roots. In such plants where the roots had been damaged, the stems were short and slender and the development of the heads was hindered or completely prevented (Fig. 7). Destruction of the roots at a later stage caused the heads to become shrivelled or small-grained, but this did not affect the length of the stem. In general the symptomatology of take-all was visible in the stem bases in both winter and spring wheat in 1976 and 1977. In these cases thete was a positive correlation between the symptoms and the occurrence of Gaeumanno- myces graminis. In 1977 a similar correlation was found in both rye and oats. In contrast, however in barley G. graminis seldom caused the typical darkening of the stem base. The stem bases of the diseased plants were often dark, sometimes even shiny black. Between the lowest leaf sheath and the stem was a thick growth of mycelia and elongated ascocarps (Plates I and II). Their oblique openings pro- truded from the sheath, and the ascospores extruded as a reddish mass. The size of the ascocarps (80 ascocarps) varied 554-968 x 370-537 ,um of which the openings measured 190-544 ,um (Plates I and II). The asci (35 asci) had a size of 95-113 ,um and the ascospores (200 spores) measured 75-95 x 3,3-3,4 ium. Spores of Phialophora sp. occurred rarely and were found in only nine samples. Most of them were encountered in seedlings of winter wheat in the autumn; only three cases were of older plants. The samples studied were the following: Barley EH: Tammela 27. 7. 1975. Spring wheat St: Humppila 27. 7. 1975. Winter wheat EH: Jokioinen 4. 8. 1975, V: Halikko 28. 10. 1976 (2 samples), Kemiö 28. 10. 1976, U: Askola 2. 11. 1976, EH: Iitti 15. 11. 1976. Rhizoctonia solani Kiihn. Rhkoctonia solani was found in mature cereals at 58 localities. There were differences in the incidence of the fungus according to the year, the cereal species and the stage of plant development. In 1976 the fungus was unusually prevalent, whereas in 1975 it hardly occurred at ali (Fig. 6). This fungus was more common in mature cereals and in seedling- s of winter cereals in the autumn than in seedlings in the spring (Tables 1 and 2). The symptomatology of Rhkoctonia solani was not distinct. The stem base could be black, variegated or spotted. Nevertheless the growth of the plant and the roots were generally normal. Under moist conditions, particularly in 1976, the roots became filled with pale-coloured or tan mycelia and also by pale sclerotia which later turned brown (Fig. 7). There were two types of mycelia. The more common type was pale and delicate, whereas the infrequent type was tan and hevier in structure (Plate IV). No correlation was found between the occurrence of R. solani and the appearance of spotted cereal stems. Neither were any regional differences observed. Septoria nodorum Berkeley. Septoria no- dorum was found in mature cereals at 41 localities. It appeared primarily in winter and spring wheat and only in small amounts in barley and rye. The fungus was common in the seedlings of winter wheat in the autumns 1975 and 1976 as well as in the springs 1977 and 1978. In mature plants it occurred in small quantities in 1976 (Fig. 6). Regional differences were observed to some degree. The fungus was somewhat more prevalent in Varsinais-Suomi and South Häme than in Uusimaa and Satakunta (Fig. 11). Septoria nodorum caused darkening of the stems, especially at the nodes. In the leaf sheaths and glumes it caused spots which had shades of yellow and brown. Later the spots became pale grey from their centres. In the spots grew large quantities of pycnidia in different shades of brown. Under moist conditions large masses of orange-reddish spores exuded. Ja diseased 241 Plate I. 1-9: Gaeumannomyces graminis. 1, 4, 5, 8: on spring wheat. 2: on barley. 3, 6, 7: on winter wheat. 9: on rye. 1 and 2: old plants with infected roots and basal parts of stem, aside with necks of numerous small perithecia breaking through the surface of leaf sheath. 3 and 5: brown runner-hyphae or macrohyphae. 4: colourless infection hyphae or microhyphae. 6: the young perithecium. 7 and 8: the ripe perithecia. 9: ascus with ascospores of the fungus. Material: 1: V. Perniö 8. 9. 1977. 2: U. Tuusula 2. 9. 1977. 3: St. Kokemäki 13. 8. 1975. 4: V. Paimio 16. 8. 1977. 5: U. Tikkurila 31. 8. 1977. 6: V. Paattinen 8. 8. 1975. 7: U. Porvoo commune 17. 8. 1976. 8: V. Koski 17. 8. 1977. 9: EH. Pälkäne 18. 8. 1975. 1, 2: X 1, 3: X 10, 4, 9: X 1000, 5: X 600 6, 7, 8: X 160. Plate II. 10-19: Gaeumannom_yces graminis. 10-17, 19: on winter wheat. 16 and 18 on rye. 10 and 11: old plants with infected roots and basal parts of stem. 12 and 13: necks of small perithecia breaking through the surface of leaf sheath. 14-16: brown runner hyphae and colourless infection hyphae. 17: the young perithecium. 18: the ripe perithecium with long, dense hairs around the neck. 19: ascus and ascospores of the fungus. Material: 10: St. Kokemäki 13. 8. 1975. 11: U. Lapinjärvi 24. 8. 1977. 12: St. Loimaa commune 4. 8. 1975. 13: Meillä 17. 8. 1977. 14: EH. Iitti 22. 8. 1977. 15: V. Vahto 15. 8. 1976. 16: EH. Somero 17. 8. 1977. 17: St. Alastaro 4. 8. 1975. 18: EH. Hattula 20. 8. 1977. 19: U. Elimäki 24. 8. 1977. 10, 11: X 1, 12: X 8, 13: X 20. 14, 15, 16: X 600 17: X 500, 18: X 200, 19: X 1000. Plate III. 20-30. 20-24: Fusarium culmorum. 20-23: on spring wheat. 24: on barley. 25: F. avenaceum on spring wheat. 26: F. graminearum on winter wheat. 27-29: Gibberella zeae. 27 and 29: on oats. 28: on winter wheat. 30: F. nivale on rye. 20-22: old plants with brown infected basal parts of stem. 23-26, 30: conidia of Fusarium species. 27 and 28: old plant with perithecia, 29 perithecium with ascus and ascospores of Gibberella zeae. Material: 20: EH. Pälkäne 18. 8. 1975. 21: U. Anjala 17. 8. 1975. 22 and 23: V. Mietoinen 19. 8 .1975; 24: Pertteli 21. 6. 1978. 25: St. Kokemäki 13. 8. 1977. 26: EH. Tammela 27. 7. 1975. 27 and 29: EP. Ylistaro 13. 8. 1975. 28: EH: Somero 4. 8. 1975. 30: U. Tuusula 3. 8. 1977. 20-22: X 1/2, 23-26, 30: X 1000, 27: X 5, 28: X 30, 29: 200. Plate IV. 31-38. 31 and 32: Pseudocercosporella herpotrichoides on winter wheat. 33-35: Bipolaris sorokiniana on barley. 36-38: Rhizoctonia solani, 36: on spring wheat, 37: on rye, 38: on oats. Material: 31 and 32: U. Artjärvi 21. 5. 1976. 33: ES. Mikkeli commune 22. 8. 1975. 34: EH. Jokioinen 27. 7. 1975. 35: ES. Juva 23. 8. 1975. 36: U. Snappertuna 19. 8. 1976. 37: V. Tenhola 19. 8. 1976. 38: St. Kokemäki 10. 6. 1976. 31: X 500, 32: X 1000, 33: X 1/2, 34: X 15, 35-38: X 500. 90- 80- RYE WINTER WHEAT 70- 0.013;%atlerpnarts 60- Ears 50- 40- 30- 20- 10- F21 P.1 z 0 rn- 2 3 23 23 I 23 1 23 1 2 3 1 2 3 1 2 3 B C D A 100- 1 1 I 2 3 I 2 3 1 2 3 I 2 3 t23 23 23 BARLEY OATS A 13 C SPRING WHEAT 1 2 3 1 2 3 I 23 0 Fig. 11. Frequency (%) of Septoria nodorum on mature wheat and barley samples researched in 1976 and 1977 at the different districts. seedlings the leaves had brown, yellow-rimmed spots; in addition, the tips of the leaves or even entire leaves were dead. In the stem base of the seedlings the tissue was brown in varying degrees, and parts of the roots were dead (Fig. 8). Bipolaris sorokiniana (Sacc. on Sorok.) Shoemaker. Bipolaris sorokiniana was encountered in mature cereals at 18 localities (Fig. 9). It occurred almost exclusively in barley, and in a few scattered cases also in wheat and rye. The fungus was rare in seedlings, being found at only 7 localities. In 1975 it was more common than in the other trial years. In its occurrence the fungus was restricted to certain fields and was found year after year in these same fields. Bipolaris sorokiniana caused darkening and indistinct spotting in the stem bases of cereals. Infected plants had a stunted growth and poor roots (Plate IV). In seedlings the damage appeared as brown spots in the stems and leaves coincidental with browning of the roots. Pseudocercosporella herpötrichoides (Fron) Deighton (Plate IV). This fungus was observed at eight localities (V, U, EH). It was occa- sionally found in the seedlings of rye and winter wheat, principally in samples collected in the autumn. Colletotrichum graminicola (Ces.) Wils. In 1977 Collectotrichum graminicola occurred com- monly in mature oats and fairly commonly in barley. In other cereals it was found only sporadically. The fungus produced large num- bers of small, sharply-defined black spots. In these spots developed conidiophores with their conidia. Fungi Fig. 12. Frequency (%) of some most important parasitic fungi on basal parts of stem and ears of mature cereal samples researched in 1975 (1), 1976 (2) and 1977 (3). A = Bipolaris sorokiniana, B = Fusarium eulmorum, C = Rhizoctonia solani, D Septoria nodorum. 246 DISCUSSION In this investigation cereal plants affected with root and foot rot were examined visually on the basis of macroscopoc symptoms in the stem bases, roots and shrivelled heads. The fungi were determined microscopically from diseased plant parts cultured in moist chambers. This pro- cedure proved to be advantageous even though it is not well suited for some phycomycetous fungi (cf. STETTER and LEROUL 1979). When the macroscopic symptoms and the microscopic results were compared, it was found that they were only partially correlated. The macroscopic symptoms varied widely or in some cases lacked completely. Consequently, determination of the fungal species was very uncertain, and often impossible (cf. NILSSON 1969, STETTER and LEROUL 1979). Previous studies on root and foot rot diseases of cereals in Finland were based primarily on visual observations of the disease symptoms (HÄRDH 1953, IKÄHEIMO- 1960, TALVIA 1970, TOIVIAINEN 1970, TEITTINEN 1974). The course of development of the disease with respect to the causal agent was consequently not esta- blished. Many factors affect , the occurrence of root and foot rot, such as weather conditions, cereal species and stage of plant development. The annual fluctuations, caused by weather condi- tions, were larger than the other variations (TALviA 1970, TOIVIAINEN 1974, VIRTANEN 1979). The warm and dry summer 1975 favoured Fusarium species, whereas they were at a mini- mum in the cool, wet summers 1977 and 1978 (cf. GLYNNE 1954, COLHOUN et al. 1968). In this study Fusarium species appeared in ali the cereals and in the different developmental stages (cf. BOOTH 1971). The most common of the species was F. culmorum, while F. avenaceum was less numerous (cf. FIARDH 1953, TOIVI- AINEN 1974, UoTI 1975), especially in seedlings in the spring (cf. COLHOUN 1964). F. graminearunz was somewhat rare (cf. HÅRDH 1953). F. nivale occurred in considerable amounts in the seedlings of rye only in the spring 1977 after an unusually long winter with a deep snow cover. This species is known in Finland only as a winter- damaging fungus causing injury to overwintering cereals, especially rye (JAXIALAINEN 1970). F. nivale is considered also to he a causal agent of root and foot rot, together with three other Fusarium species: F. culmorum, F. graminearum and F. avenaceum (DuREN and FEHRmANN 1978). F. nivale has been isolated from injured roots and from the soil (RAwEnsTsoN and COLHOUN 1969). In Denmark the incidence of Fusarium species has not been found to increase during continuous barley cultivation, neither have these fungi been found to cause noteworthy decreases in yield when infecting the roots (STETTER and LEROUL 1979). However, opposite results have also been published (UoTi 1975, VOITOVA 1977). Bz:polaris sorokiniana occurred likewise more commonly in the warm, dry summer 1975 than in the other years (cf. SKOU 1966, JORGENSEN 1974). The fungus was predominantly a pathogen of barley and was somewhat rare. In the nordic countries the fungus is found primarily in barley seedlings (KoLK and OLSSON 1975, KURPPA 1976, OLOFSSON 1976,, FIjoRsTrimm 1979). In Danish trials with continuous barley cultivation the fungus was much more prevalent after the 8th and 9th years than after the first, third and fourth years. The effect of B. sorokiniana .in causing lower cereal yields was at least as great as that of Gaeumannomyces graminis (STETTER and LEROUL 1979). The cool and • dry summer 1976 favoured especially Rhioctonia solani (PITT 1964, REINECKE 1977). The fungus was more prevalent in mature plants than in seedlings. Its most serious damage, however, is considered to he inflicted to seed- lings (PITT 1964). The fungus is found wide- spread in ali the nordic countries, although its 8 1280021321 247 significance as a pathogen is believed to he minor (HANSEN 1963, PETERSEN 1963, TALVIA 1970, TOIVIAINEN 1974, NILSSON 1974 a). The wet and cool summer 1977 was favourable especially to Gaeumannomyce's graminis. This situation has been observed previously in Fin- land (IKÄHErmo 1959, TOIVIAINEN 1974) and is typical for this fungus (NmssoN 1969, WALKER 1972). In the present study the fungus occurred in mature plants, predominantly in winter and spring wheat (cf. MIEL KE 1974) and commonly Also in barley and rye, but only very- rarely as a vegetative mycelium in oats. Thus the culture of G. graminis var. avenae isolated by TOIVIAINEN (1966) from oats remains as a rare single case in Finland. On the other hand, the fungus is known to cause damage to oats e.g. in Norway (HANSEN 1964). In Danish trials with continuous barley cultivation Gaeumannomyces graminis occurred in the greatest numbers in the third and fourth years, and rarely in the first or ninth years (STETTER and LEROUL 1979). Take-ali decline is known, also in some Norwegian soils (MAG- NUS 1979), as in many other countries (cf. HORNBY 1979). The declines in yield caused by this fungus were quite large (FljoRsTHoLm 1979). Yield declines during monoculture have gener- ally been known to he greatest in the third to fifth years (GUNNIN GHAM 1975, JENSEN 1975, TEITTINEN 1977). Wet growing seasons were also favourable to Septoria nodorum (cf. j ORS TA D 1967, BRÖNNIMANN 1968). The fungus was most common in winter wheat, especially in seedlings in autumn. Such is the situation elsewhere, too (BköNNImANN 1968, KOLK and OLSSON 1975, JEN KYN and KING 1977). Also the species Pseudocercosporella herpotric- hoides thrives in cool, wet weather conditions ( J OR GENSEN 1964). In the present study the fungus was found sporadically in the seedlings of winter wheat' particularly in the autumn. Also in Sweden, autumn infection is considered to he more serious in winter wheat than spring infection (OLvÅNG 1978). The fungus is common in the nordic countries (JoRsTAD 1956, PETERSEN 1963, NILSSON 1974 b), in the Baltic countries (KoRsHuNovA 1968) and is widespread through- out Europe (Cmi Map 74, 1969). In Finland the fungus has been previously observed in large amounts especially in spring wheat (FIÄRDH 1953) and in barley (TALvIA 1970). On the other hand, there is uncertainty about the significance of the disease (TOIVIAINEN 1974). The divergence in results may be due partly to possible changed conditions but primarily to inaccuracy in the research methods. The effect of root and foot rot diseases on the yield levels is difficult to ascertain in this sort of study, despite its great importance. In the area of this study the average cereal yields fluctuated widely in the different years (OFF. STATIST. FINL., A GRIC. 1975, 1976, 1977). In 1975 the yields were somewhat higher than normal, with only rye giving lower than normal yields in Varsinais-Suomi as a result of severe spring frost damage. In 1976 the cereal yields were exceptionally large, amounting to as much as 20-30 % higher than average for rye, barley and oats, while wheat yielded about the same as in 1975. In contrast the 1977 yields were unusually low. Compared to the 1975 yields, the 1977 levels were lower by the following amounts: winter cereals 20-30 %, spring wheat slightly less, barley about 10 % and oats only slightly lower than in 1975. The number of shoots in the mature cereals was somewhat greater in 1976 than in 1977. This confirms, although not convincingly, the view (cf. TEITTINEN 1977, OLSSON 1978) that such yield reductions are due to root and foot rot diseases which decrease the number of shoots per plant. In 1976 there were considerably more shriv- elled heads in winter cereals, especially winter wheat than in 1977. On the other hand, in 1976 the yields were much higher than in 1977. Consequently the numbers of shrivelled heads are not a reliable indication of the yield-reducing 248 effect of root and foot rot diseases (cf. HÅRDH 1953, IKÄHEIMO 1960). The occurrence of shrivelled heads can be due to many factors, e.g. frost damage. The total numbers of fungi as well as the numbers of parasites in the mature cereals and • seedling samples were greater in 1976 than in 1977. Exceptions were barley and oats, in which there were more fungal species in 1977 than in 1976 (MÄKELÄ and MÄKI 1980). It has been observed (PETERSEN et al. 1976) that as the soil moisture decreases the frequency of micro- organisms in the root level increases. In the present study Rhkoctonia solani was very com- mon in 1976, particularly in mature cereals. Similarly Fusarium species, especially F. culmo- rum; occurred somewhat commonly. The large total numbers of fungi as well as the prevalence of root and foot rot are not reflected in the 1976 yield levels, which were exceptionally high. The advantageous weather conditions in this year masked the effect of other factors (cf. OLSSON 1978). The weather conditions in 1977 were extremely unfavourable for cereal development. In that year Gaeumannomyces graminis occurred about three times more abundantly in wheat and rye, and about five times more abundantly in barley than in 1976. This fungus is known to be pre- valent in wet years (SKIPsNA 1961, NILSSON 1969, COOK 1972, GRIGER 1972, Voi-rOvÄ 1977). In the present study the cereal yields were ex- ceptionally low. It is known that this fungus causes considerable yield losses (SHIPToN 1972, OLSSON 1978, WESTE 1978, STETTER and LEROUL 1979). In 1977 also Septoria nodorum occurred much more abundantly in wheat, especially winter wheat, than in 1976, The fungus is an important pathogen under moist conditions (BEocK 1957, OBST 1969, JENKYN and KING 1977). It may also cause considerable declines in yield (SmEDE GÄRD- PETERSEN 1974, JONES 1975, KING 1977). It is obvious that in years with unfavourable weather conditions the deterimental effect of certain kinds of fungal damage is intensified, although it is difficult to establish the separate effects of the individual factors (cf. OLSSON 1978). Part of the yield losses caused by root and foot rot diseases is due to the fact that the seedlings die and the number of plants in 'the, stand decreases (cf. SLOPE 1968, WEs.rE 1975). Especially seedlings of winter cereals suffer losses during the winter (NILssoN 1969, MAGNUS and HANSEN 1973, HAEGEMARK and OLVÄNG 1976). In the present study many species of fungi causing root and foot rot occurred in the seedlings. The bulk of them were the same species as those found in the mature plants (cf. MÄKELÄ and MÄKI 1980). There were many injuries and at the same time more pathogenic fungi in the seedlings of winter cereals than in those of spring cereals. In addition to the present study, the authors found in a preliminary cereal monoculture trial on silt soil at the Pälkäne experimental station in South Häme that 50 % of the seedlings of winter wheat and 10 °/„ of the rye seedlings died during the winter 1977- 1978. Fusarium nivale was encountered only in small amounts in the rye seedlings in the spring. On the other hand, other Fusarium species, especially F. culmorum and F. avenaceum, occurred in winter wheat and rye, both in the seedlings and in the mature stands. The same situation was observed for Rhi.zoctonia solani. In mature stands Gaeumannomyces graminis was found, and in seedlings of winter wheat additionally Sep- toria nodorum occurred. In the opinion of the authors, root and foot rot diseases as a cause of destruction to seedlings of winter cereals, especially winter wheat, in southern and southwest Finland, are very im- portant and can be compared with the so-called winter damage caused by low temperature fungi. Such winter damage has generally been con- sidered to be caused exclusively by Fusarium nivale, 'the classical winter damage fungus. This fungus rarely occurred in large numbers in the area of investigation and then only in rye 249 to any noteworthy extent (cf. BLOMQVIST and JAMALAINEN 1968). On the other hand, every spring, seedlings of winter wheat can be found which were damaged during the winter to a greater or lesser extent depending on the circumstances. This view is supported also by studies of the fungi in cereal heads (Table 4). Fusarium nivale was found only in one sample of rye in autumn 1977. In contrast, many other Fusarium species were encountered in the heads of ali the different cereals, with F. culmorum being most prevalent and F. avenaceum also in considerable amounts. Among the other fungi causing root and foot rot were Septoria noddrum commonly in the heads of winter wheat and less frequently in those of barley, and Bipolaris sorokiniana in barley heads. REFERENCES ANDERSEN, H. J. 1979. Migratory nematodes in Danish barley fields. II. Population dynamics in relation to continuous barley growing. Danish J. Pl. Soil Sci. 83: 9-27. BOCKMANN, H. & KNOTH, K. E. 1965. Zur Ertrags- bildung von Sommerweizen nach verschiedenen Vorfriichten unter besonderer Beriiksichtigung der Schäden durch Fusskrankheiten. Z. Pfl. Krankh. Pfl. Path. Pfl. Schutz. 72: 385-398. & KNoTH, K. E. 1971. Der verstärkte Getreideban aus Pflanzenhygienischer sicht. Z. Pfl. Krankh. Pfl. Path. Pfl. Schutz. 78: 1-33. BOOTH, C. 1971. The genus Fusarium. 237 p. Kew, Surrey, England. BRÖNNIMANN, A. 1968. ZUT KerIDIDIS VOI1 Septoria nodorum Berk., dem Erreger der Spelzenbräune und einer Blattdiirre des Weizens. Phytopath. Z. 61: 101- 146. COLHOUN, J. 1964. Fusarium diseases of cereals. I. Infection of wheat plants, with particular reference to the effect of soil moisture and temperature on seedling infection. Trans. Brit. Mycol. Soc. 47: 559-572. , TAYLOR, G. S. & TOMLINS ON, R. 1968: Fusarium diseases of cereals. II. Infection of seedlings by F. culmorum and F. avenaceum in relation to environmental Factors. Trans. Brit. Mycol. Soc. 51: 397-404. COOK, R. J. 1972. Influence of low plant and soil water potentials on diseases caused by soilborne fungi. Phytopath. 63: 451-472. D OMSCH, K. H. & GAMS, W. 1968 a. Die Bedeutung vorfruchtabhängiger Verschiebungen in der Boden- mikroflora. I. Der Einfluss von Bodenpilzen auf die Wurzelentwicklung von Weizen, Erbsen und Raps. Phytopath. Z. 63: 64-74. & GAMS, W. 1968 b. Die Bedeutung vorfruchtabhän- giger Verschiebungen in der Bodenmikroflora. II. Antagonistische Einfliisse auf pathogene Bodenpilze. Phytopath. Z. 63: 165-176. DUBEN, J. & FEHRMANN, H. 1978. Occurence and pathogenity of Fusarium spp. on winter wheat. 3rd Int. Congr. Pl. Path. Miinchen, 16-23 Aug. 1978. - Abstr. Pap. p. 193. GUNNIN GHAM, P. C. 1975. Some consequences of cereals monoculture on Gaeumannom_yces graminis (Sacc.) Arx & Olivier and the take-all disease. EPPO Bull. 5: 297-317. HAE GEMARK, V. 8c OLVÄN G, H. 1976. Stråknäckar- svampen-biologi, bekämpning, betydelse, Växtskydds- notiser 40: 86-88. HANSEN, L. R. 1963. Skarp oyeflekk på korn forårsaket av- Rbizoctonia solani Kiihn. Meld. Norg. Landbr. Hoisk. 42: 13. - 1964. En sammenlikning av Ophiobolus graminis Sacc. var. graminis og Opbiobolus graminis Sacc. var. avenae E. M. Turner. Meld. Norg. Landbr. Hoisk. 43. 12 p. A. 1933. Viljalajien tyvitaudeista. Maatalous 10: 258-259. HjoRrsHoLm, K. 1979. Ensidig bygdyrkning. I. Indfly- delsen på plantevaekst og jordbundsforhold. Conti- nuous barley growing. I. Influence on plant growth and soil conditions. Danish J. Pl. Soi! Sci. 83: 32-49. HORNBY, D. 1979. Take-ali, decline: a theorist's paradise. Soil-borne plant pathogens. p. 133-156. London. H.tRDH, J. E. 1953. Kevätvehnän kahutähkäisyydesta sekä sen syistä Suomessa. Ref.: On the shrivelheads of spring wheat and their causes in Finland. 152 p. Helsinki. I K ÄHEIMO, K. 1959. Ophiobolus graminis Sacc. todettu maassamme kevätvehnässä. Summary: The deter- mination of Opbiobolus graminis Sacc. on spring wheat in Finland. J. Sci. Agric. Soc. Finl. 31: 180-183. - 1960. Viljan tyvitaudit ja niiden torjunta. Summary: Cereal foot-rot diseases and their control in Finland. Maata!, ja Koetoim. 18: 182-192. JAMALAINEN, E. A. 1946. Vehnän kevyttähkäisyydestä. Maatalous 12: 158-161. 250 - 1970. Studies on Fusarium fungi in Finland. Ann. Acad. Sci. Fenn. A IV, Biologia 168: 54-56. JENKYN, J. E. & KING, J. E. 1977. Observations on the origins of Septoria nodorunz infection of winter wheat. Pl. Path. 26: 153-160. JENSEN, A. 1975. Danish experiences with cereals in monoculture. EPPO Bull. 5: 181-191. JEPSEN, H. M. & JENSEN, A. 1976. Continuous cereal growing in Denmark; experimental results. EPPO Bull. 6: 371-378. JONES, D. G. 1975. Comparative effects of Septoria nodorum on spring wheat and barley. Pl. Path. 24: 199-201. JÖRGENSEN, J. 1964 a. Investigation on loss in yield due to attack by Cercosporella berpotricboides Fron in field experiments with winter wheat. Acta Agric. Scand. 14: 1220. = 1964 b. Some observations on the effect of temperature on the sporulation of Cercosporella herpotrichoides Fron. Acta Agric. Scand. 14: 126-128. 1969. Species of Fusarium and Helminthosporium on seeds of barley grown in Denmark during 1965-1967. Acta Agric. Scand. 19: 92-98. KIETREIBER, M. 1961. Die Erkennung des Septoria - Befalles von Weizenkörner bei Saatgutpriifung. Pfl. schutzber. 20: 129-157. KING, J. E. 1977. Surveys of diseases of winter wheat in England and Wales 1970-75. Pl. Path. 26: 8-20. KoLK, H. & OLSSON, L. 1975. Seedling injuring fungi on cereal seeds in Sweden. Medd. Stat. Växtskyddsanst. 16: 139-148. KURKI, M. 1979. Suomen peltojen viljavuuden kehi- tyksestä. Viljavuuspalvelu Oy. 41 p. Helsinki. KURPPA, A. 1976. Helmintbosporium sativum Pammel, King & Bakke ohran tyvi- ja lehtilaikun aiheuttajana. Manuscr. 72 p. [Available at Univ. Helsinki, Dept. Pl. Path.] LARGE, E. C. 1954. Growth stages in cereals. Illustra- tion of the Feekes scale. Pl. Path. 3: 128-129. MAGNUS, H. 1979. Take-all (Gaeumannomyces graminis) ,clecline in some Norwegian soils. Meld. Norges Landbr.Hoisk. 58: 1-11. & HANSEN, L. R. 1973. Tolerance to Cercosporella berpotricboides Fron in winter wheat. Phytopath. Z. 76: 189-199. MÄKELÄ, K. & MÄKI, L. 1980. The occurrence of micro- mycoflora in the culm base and roots of cereals in southern Finland. Ann. Agric. Fenn. 19: 187-222. MIELKE, H. 1974. Untersuchungen iiber die Anfälligkeit verschiedener Getreidearten gegen den Erreger der . Schwarzbeinigkeit Ophiobolus graminis Sacc. Mitt. Biol. Bundesanst. Land. Forstwirt. (Berlin-Dahlem) No 160. 61 p. NILSSON, H. E. 1969. Studies on root and foot rot diseases of cereals and grasses. I. On resistance to Ophiobolus graminis Sacc. Lantbr.högsk. Ann. 35: 275-807. 1974 a. Angrepp av olika isolat av rotdödarsvampen (CaeumannomyCes graminis). Nord. Jordbr.forskn. 56: 358-360. 1974 b. Förekomsten av stråbassjukdomar i Sverige 1973. Nord. Jordbr.forskn. 56: 390-393. NYSTRÖM, S. 1976. Verksamheten vid försöksavdelningen för växtföljder. Resultat från långtidsförsöken. Landbr. högsk. Inst. växtodl. Rapp. avhandl. 41: G1-G7. OBST, A. 1976. Untersuchungen zur Epidemiologie, Schadwirkung und Prognose der Spelzenbräune (Septoria nodorum) des Weizens. Bayer. Landw. J.buch 54: 72-117. OLOFSSON, B. 1976. Undersökningar rörande Drechslera- atter hos korn och havre. Investigations on Drechslera species in barley and oats. Stat. Växtskyddsanst. Medd. 16: 323-425. OLSSON, P. 1978. Samband mellan rotdödarangrepp och kärnavkastning i ett växtföljdsförsök med korn. Nord., Jordbr.forskn. 60: 459-460. OLVÄNG, H. 1978. Sambandet stråknäckarangrepp - skörd. Nord. Jordbr.forskn. 60: 445-446. PETERSON, E. A., ROUATT, J. W. & KATZNELSON, H. 1965. Micro-organisms in the root zone in relation to soil moisture. Can. J. Microbiol. 11: 483-489. (Ref. Rev. Appl. Biol. 45: 336). PITT, D. 1964. Studies on sharp eyespot disease of cereals. I. Disease symptoms and pathogenicity of isolates of Rhizoctonia solani Kiihn and the influence of soil factors and temperature on disease development. Ann. Appl. Biol. 54: 77-98. PREW, R. D. 1980 a. Studies on the spread of Gaeuman- nonz_yces granzinis var. Iriiici in wheat. I. Autonomous spread. Ann. Appl. Biol. 94: 391-396. 1980 b. Studies on the spread of Gaeumannomyces graminis var. tritici in wheat. II. The effect of culti- vations. Ann. Appl. Biol. 94: 397-404. RAININKO, K. 1972. Peltovaramme ja niiden käyttö. Tuottava Maa 2: 20-31. RAWLINSON, C. J. & COLHOUN, J. 1969. The occurrence of Fusarium nivale in soil. Pl. Path. 18: 41-45. REINECKE, P. 1977. Untersuchungen zum Erregerspect- rum des Fusskrankheitskomplexes and Getreide unter besonderer Beriicksichtigung von Rbizoctonia solani Diss. 141 p. Göttingen. REUTER, E. 1912. 16. kertomus tuhohyönteisten esiinty- misestä Suomessa vuonna 1910. Maanvilj hall. Tied. 84: 1-17. SALT, G. A. 1976. A survey of Fungi in Cereal Roots at Rothamsted, Woburn and Saxmundham, 1970-1975. Rothamsted Rep. 1976, 2: 153-168. 251 SHIPPERS, B. & GAMS, W. 1979. Soil-borne plant patho- gens. 686 p. London. SHIPTON, P. J. 1975. Yield trend during take-ali decline in spring barley and wheat grown continously. EPPO Bull. 5: 281-453. SKIPSNA, J. 1961. P&igumi par Kvieki saknu puvi (Ophiobolus graminis Sacc.) un täs apkaroknu ziemas Kvieåu sjumos Latvijas PSR rietumu joslas rajonos. [Study on root rot of wheat (Ophiobolus graminis) and its control in winter wheat crops in the western areas of the Latvian S.S.R.] Angsne RaS'a Riga. 10: 141- 160. (Ref. Rev. Appi. Myc. 42: 10). Sxou, J. P. 1966. The conidial stage of Cocbliobolus sativus as a potential pathogen and as cause of a disguised disease in cereals in Denmark. Friesia 8: 57-75: SLOPE, D. B. 1968. The benefits and limitations of breadcrops for the control of soil-borne diseases of cereals. J. Nat. Inst. Agric. Bot. 11: 54-57. SMEDEGARD -PETERSEN, V. 1974. Leptospbaeria nodmuu (Septoria nodorum) a new pathogen on barley in Den- mark and its physiologic specialization on barley and wheat. Friesia 10: 251-264. SP RA GUE, R. 1950. Diseases of cereals and grasses in North America. 538 p. New York. STETTER, S. & LEROUL, N. 1979. Ensidig bygdyrkning. II. Indflydelsen på. roddernes svampeflora. Continuous barley growing. II. Influence on the fungal population of the roots. Danish J. Pl. Soil Sci. 83: 50-72. TALVIA, P. 1970. Erfarenheter av monokulturförsök med stråsäd i Finland 1963-1968. Nord. Jordbr.forskn. 52: 249-250. TEITTINEN, P. 1974. Stråbassjukdomar i olika, odlings- förhållanden. Nord. Jordbr.forskn. 56: 33-34. - 1977. Satotason muutokset yksipuolisessa viljan- viljelyssä. Koetoim. ja Käyt. 12: 45, 46. TOIVIAINEN, M. 1966. Tyvitaudit - vakava viljanviljelyn vitsaus. Koetoim. ja Käyt. 23, 9: 33. - 1970. Förekomst av stråbassjukdomar i Finland. Nord. Jordbr.forskn. 52: 247-248. - 1974. Viljan tyvitaudit, erityisesti mustatyvi (Gaeuman- nomyces graminis Sacc.) von Arx & Olivier. Manuscr. 89 p. [Available at Univ. Helsinki, Dept. Pl. Path.] UOTI, J. 1975. Occurence and pathogenicity of Fusarium species in cereals in Finland. EPPO Bull. 5: 419-424. VETROV, Yo. F., KORSHUNOVA, A. F., MORSCHCHATSKII, A. A., KHOKHRYAKOV, M. K. & CFIULKINA, V. A. 1971. Kornevy-egnili khlebnykh zlakov v SSSR. [Root rots of cereals in the USSR.] Mikol. i Fitopatol. 5: 148-155. (Ref. Rev. Pl. Path. 50: 653.) VIRTANEN, R. 1979. Yksipuolisen viljanviljelyn seurauk- sista. Manuscr. 83 p. [Available at Univ. Helsinki, Dept. Pl. Husb.] VohovA, L. R. 1977. [Seed infection of barley by root rot.] Semennaya infektsiya kornevOi gnili yachmenya. Zashcitta Rastenii 10: 46-47. (Ref. Rev Pl. Path. 57: 445). WALKER, J. 1973. Gaeumannomyces graminis. C.M.I. Descript. Path. Fungi Bact. 381-383. - 1975. Take-all diseases of Gramineae: a review of recent work. Rev. Pl. Path. 54, 3: 113-144. WEsTE, G. 1975. Comparative pathogenicity of root parasites to wheat s'eedlings. Trans. Brit. Mycol. Soc. 64: 43-53. - 1978. Comparative pathogenicity of six root parasites towards cereals. Phytopath. Z. 93: 41-55. Manuscript received 16 Jono 1980 Kaiho Mäkelä and Päivi Parikka Agricultural Research Centre Institute of Plant Pathology SF-01300 Vantaa 30, Finland SELOSTUS Viljan tyvitautien esiintyminen Etelä-Suomessa vuosina 1975-1978 KAIHO MÄKELÄ ja PÄIVI PARIKKA Maatalouden tutkimuskeskus Aineisto kerättiin vuosina 1975-1978 maan tärkeimmiltä leipäviljan tuotantoalueilta Lounais- ja Etelä-Suomesta pääasiassa viljelijäin pelloilta ja Maatalouden tutkimus- keskuksen koeasemilta. Tällä alueella on yksipuolista vilj anvilj elyä harjoitettu tehokkaasti 1950-1960-luvuilta lähtien. Aineisto käsitti 1035 tuleentunutta viljanäytettä 119 paikkakunnalta ja 1029 orasnäytettä 91 paikkakun- nalta ja edusti kaikkia viljalajeja, runsaimmin vehnää ja ohraa. Vioittumat arvioitiin (20 yksilöä/näyte) kasvin tyvistä ja juuristosta silmävaraisesti. Sienet määritettiin kosteuskammiomenetelmää käyttäen mikroskooppisesti. Korjuuaikaan syksyllä oli valtaosa viljan tyvistä ja juuristosta jollakin tavoin vioittuneita. Terveitä yksilöitä oli vähiten (vuosina 1976 ja 1977 keskim. 7-23 %) 252 ohralla ja syysvehnällä, eniten (keskim. 30-80 %) kauralla. Lievästi vioittuneita kirjavia tyviä ja kohtalaisen hyviä jUuristoja oli noin puolella tutkituista tuleentuneista yksilöistä kaikilla viljoilla. Ankarasti vioittuneita, tum- muneita tyviä ja huonoja juuristoja oli eniten (keskim. 35-45 %) vehnällä ja ohralla, vähiten (alle 10 %) kauralla. Oraat olivat terveempiä kuin tuleentuneet viljat. Kevätviljan oraat olivat terveempiä kuin syys- viljan oraat. Syysviljan oraat olivat syksyllä terveempiä kuin keväällä, nimenomaan lehdistöltään. Kaura oli kaiken ikänsä muita viljoja terveempää. Vuosien välillä oli eroavuutta vioitusten määrissä. Myös kahujen tähkien määrä vaihteli viljalajeittain ja vuosittain. Eniten niitä oli syysvehnällä, vähiten kauralla ja ohralla. Tyvitautisymptomit ja niitä aiheuttavien sienten esiin- tyminen vastasivat toisiaan vain osittain. Sienilajit ja niiden yleisyys vaihtelivat suuresti viljalajista, kehitys- asteesta, vuodesta ja kasvupaikasta riippuen. Eniten sieniä esiintyi vehnällä ja ohralla, vähiten kauralla. Tuleen- tuneissa viljoissa ja syysviljan oraissa oli sieniä enemmän kuin kevätviljan oraissa. Eri tyvitautien aiheuttajat olivat vallitsevia erilaisina kasvukausina. Niinpä Gaeumanno- myces graminis ja Septoria nodorum esiintyivät yleisimmin sateisina ja viileinä kesinä,, Fusarium lajit taas suosivat lämpimiä säitä. Meillä tärkein syy tyvitautien vaihteluihin on löydettävissä juuri ilmastollisista tekijöistä. Yleisimmät sienet olivat Fusarium culmorunz (W. G. Smith) Sacc., Gaeumannomyces graminis (Sacc.) v. Arx et Olivier, Rhizoctonia solani Kiihn ja Septoria nodorum Berkeley. Fusarium culmorum esiintyi yleisenä kaikilla vilja- lajeilla, eri ikäisissä kasvustoissa ja eri alueilla. Se suosi lämmintä kasvukautta 1975. Muita Fusarium lajeja määri- tettiin toistakymmentä. Näistä oli melko yleinen F. avenaceum (Corda ex Fr.) Sacc. harvinainen puolestaan F. graminearum Schwabe ja sen kestoaste Gibberella zeae (Schw.) Petch., .F. nivale (Fr.) Ces. esiintyi yleisenä vain rukiin oraissa keväällä 1977. Merkittävä oli Gaeumannomyces graminis, mustatyven aiheuttaja. Sieni oli yleisin vehnällä, yleinen myös ru- kiilla, harvinaisempi ohralla. Kauralla sientä esiintyi tuskin lainkaan. Sateisena ja viileänä kasvukautena 1977 oli sientä huomattavasti enemmän kuin kahtena edellisenä vuonna. Myös alueellista eroavuutta esiintyi. Rbizoctonia solani, tyvi- ja juurilahon aiheuttaja, oli yleisempi syksyllä kuin keväällä. Sieni suosi viileää ja vähäsateista kasvukautta 1976. Septoria nodorum esiintyi ennenmuuta syysvehnällä yleisempänä oraissa ja tähkissä kuin tuleentuneissa kasvustoissa. Kosteina kasvukausina ja niitä seuraavina vuosina sientä oli runsaasti. Myös alueellisesti eroavuutta esiintyi. Bipolaris sorokiniana (Sacc. on Sorok.) Shoemaker, ohran tyvi- ja lehtilaikun aiheuttaja, oli pääasiassa ohrassa, tuleentuneissa kasvus- toissa ja tähkissä peltokohtaisena. Pseudocercosporella berpotricboides (Eron) Deighton, tyvilaikun aiheuttaja, todettiin vain satunnaisesti syysviljan oraissa syksyisin. Collectotricbum graminicola (Ces.) Wils. oli yleinen tuleen- tuneessa kaurassa 1977 ja melko yleinen ohrassa. Sienten suuri kokonaismäärä, sen paremmin kuin tyvitauteja aiheuttavien sienten, kuten Rhizoctonia solanin ja Fusarium lajien yleisyys ei ole näkyvissä vuoden 1976 satotasossa, joka oli poikkeuksellisen korkea. Edulliset sääolot vuonna 1976 peittivät muitten tekijöitten vaiku- tukset. Sen sijaan vuonna 1977, jolloin viljojen satotaso oli erittäin alhainen, esiintyi Gaeumannomyces graminista veh- nillä, ohralla ja rukiilla. Samoin Septoria nodorumia syys- vehnällä paljon yleisemmin kuin vuonna 1976. On ilmeistä, että sääsuhteiltaan epäedullisina vuosina myös määrättyjen sienituhojen merkitys korostuu,' vaikkakin eri tekijäin osuutta on vaikea eritellä. Tyvitautien aiheuttamista satotappioista osa johtuu Siitä, että oraita kuolee ja kasvuston yksilöluku vähenee. Tämä koskee varsinkin syysviljoja, ennen muuta syys- vehnää. Näillä tyvitautien merkitys orastuhojen aiheutta- jina Etelä- ja Lounais-Suomessa on rinnastettavissa ns. talvituhoihin. Näitä on vanhastaan pidetty yksinomaan ns. talvituhosienten, nimenomaan Fusarium niva/en ai- heuttamina. Tätä sientä esiintyy tutkimusalueilla runsaasti harvoina talvina ja silloinkin merkittävänä vain rukiilla. Sen sijaan huonosti talvehtinutta syysviljan orasta ja lukuisia Fusarium-lajeja, Seplaria nodorumia ja muita tyvitautien aiheuttajia tapaa pelloilla joka kevät, enemmän tai vähemmän olosuhteista riippuen. Tätä käsitystä tukevat myös viljojen tähkistön sienitutkimukset. Fusa- rium nivalea esiintyi vain rukiin tähkissä yhdessä näyt- teessä syksyllä 1977. Sen sijaan esiintyi kaikilla viljoilla yleisenä monia edellä mainittuja tyvitautien aiheuttajia. 253 ANNALES AGRICULTURAE FENNIAE, VOL. 19: 254-259 (1980) Seria PHYTOPATHOLOGIA N. 74— Sarja KASVITAUDIT n:o 74 TOBACCO MOSAIC VIRUS (TMV) TYPES FROM TOMATO IN FINLAND' ANNIKKI LINNASALMI LINNASALMI, A. 1980. Tobacco mosaic virus (TMV) types from tomato in Finland. Ann. Agric. Fenn. 19: 254-259. (Agric. Res. Centre, Inst. Plant Path., SF-01300 Vantaa 30, Finland.) In the tobacco mosaic virus (TMV) material from tomato (Lycopersicon esculentum Mill.) in Finland (1962-65) three main groups were characterized: the mild green mosaic, by far the most prevalent (93 %), the yellow mosaic (4 %) and the severe green mosaic (3 %) types, which occurred only sproradically. The types are characterized by their symptomatology in tomato and in five Nicotiana-test plants (N. tabacum L. cv. Samsun and cv. Xanthi, N. glutinosa L., N. rustica L. and N. sylvestris L.) as well as on the basis of their thermal inactivation point (TIP), RNA base composition and amino acid composition. The analyses were performed on a total of 55 isolates. Index words: TMV types in tomato, symptomatology, TIP, RNA bases, amino acids, Finland. In connection with the study made in the years 1962-65 (LINNASALMI and MURTOMAA 1966) on the distribution of tomato viruses in Finland, 55 isolates were selected on the basis of prelimi- nary tests from TMV material (445 samples) for classification studies. Three main groups could be.characterized in the material, and they are referred to in this paper as mild gr e en mosaic (47 isolates), yellow mosaic , (4 isolates) and severe green mosaic (4 isolates) TMV types. The mild green mosaic type is by far the most prevalent (93 °/0); both yellow mosaic (4 %) and severe green mosaic 1) The main part of these results were presented in a lecture held 16. 9. 1975 at the II International conference on progress and problems in vegetable virus research in Avignon, France. (3 %) types occur only sporadically in our tomato cultivations. The classification of these types is based on the symptomatology of isolates in the tomato Lycopersicon esculentum Mill. cv. Bonner Beste and in the testplants Nicotiana tabacum L. cv. Samsun and cv. Xanthi, N. glutinosa L., N. rustica L. and N. sylvestris L., as well as on determinations of TIP, RNA base composition, total amino acid composition and carboxyl terminal amino acid. The biological and chemical analysis methods used are described in earlier publications (LINNASALMI 1966, LINNASALMI and MURTOMAA 1966, LINNASALMI and RASHID 1969). Symptos m characteristics of the types in different ho'sts are shown in Table 1. 254 Table 1. Symptoms of TMV types in different host plants and their thermal inactivation points. Host plant Mild green mosaic Yellow mosaic Severe green mosaic L. estulentum cv. Bonner Beste green mosaic yellow mosaic green mosaic, leaf curling, mild stunting N. tabacum green mosaic, mild leaf yellow mosaic, ± dis- severe green mosaic, leaf curling and cv. Samsun curling, necrotic local lesions tinct ringspots, no necrotic local lesions blister-like malformation, stunting, no necrotic local lesions cv. Xanthi necrotic local lesions necrotic local lesions necrotic .local lesions N. glutinosa necrotic local lesions necrotic local lesions necrotic local lesions N. rustica ± necrotic local + necrotic local severe green mosaic, leaf curling and lesions lesions blister-like malformation, stunting„ ± necrotic local lesions N. sylvestris necrotic local lesions necrotic local lesions severe green mosaic, leaf curling and blister-like malformation, stunting„ no necrotic local lesions TIP °C 82-84, 88-90 82-84 92-94 It should be mentioned that no symptoms whatever appeared on the fruit in the experi- ments. Apparently TMV damage on tomato fruits is generally rare under Finnish conditions. The systemic symptoms of the mild green mosaic type are mild both in tomato (Fig. 1 a) and Samsun tobacco (Fig. 2 a). According to the thermal inactivation point (TIP), the type can be divided into two groups, one with a TIP of 82-84 °C and the other with 88-90 °C. No essential symptomatological differences were found, except that the systemic mosaic symptoms in the 88-90 °C group were usually a little stronger, especially in Samsun tobacco. The systemic symptoms of the yellow mosaic type in tomato (Fig. 1 b) and Samsun tobacco (Fig. 2 a) are expressed chiefly as a yellow mosaic. The TIP is low, only 82-84 °C. The systemic symptoms of the severe green mosaic type are very strong in the tobacco species (Fig. 2 a—c), while the symptoms in tomato (Fig. 1 c) differ less from symptoms caused by the mild green mosaic in tomato. A feature in common with the yellow mosaic type is the lack of necrotic local lesions in Samsun. The TIP is very high, 92-94 °C. The mean results of the chemical analyses are shown in Table 2. Table 2. Chemical composition of TMV types. Types Mild green mosaic Yellow mosaic Severe green mosaic RNA bases moles % guanine 24,9 24,0 26,0 adenine , 29,4 30,7 28,6 cytosine 17,5 17,3 18,0 uracil 28,3 28,0 27,5 Amino acids res dues per subunit Asp 18 18 19 Thr 16 16 15 Ser 14 15 15 Glu 20 20 17 Pro 9 9 8 Gly 6 6 6 Ala 11 11 15 Vai 15 15 14 Cys 1 1 1 Met 1 1 lie 6 6 8 Leu 14 13 12 Tyr 5 5 4 Phe 8 8 8 Lys 2 2 2 Arg 9 9 11 Try 3 3 3 Total 158 158 158 C-terminal acid serine serine threonine 1) Data from LINNASALMI and RASHID 1969. 9 1280021321 255 mild green mosaic yellow mosaic severe green mosaic Fig. 1 a—c. Systemic symptoms of TMV types in tomato cv. Bonner Beste. Orig. 256 a. N. tabacum cv. Samsun from left: yellow mosaic, mild green mosaic, severe green mosaic (systemic symptoms) b. N. rustica from left: control, mild green mosaic (local lesions), yellow mosaic (local lesions), severe green mosaic (systemic symp- toms) c. N. .fylvestris from left: control, mild green mosaic (local lesions) yellow mosaic (local lesions), severe green mosaic (systemic symp- toms) Fig. 2 a—c. Symptoms of TMV types in Nicotiana test plants. Orig. 257 The RNA base ratios of ali types are similar, except for a small difference in the proportions of guanine and adenine for the severe green mosaic compared with the values for the other types. There is a similarity in amino acid composition between the mild green and yellow mosaic types, as is evidenced in the amounts of amino acid residues; likewise the carboxyl terminal acid is the same for both, namely serine. The severe green mosaic type differs essentially from the previous two; it is lacking in methionine, and its carboxyl teminal acid is threonine. With regard to their symptomatology and amino acid composition, parallels can be drawn between the Finnish TMV types presented in this paper and certain strains of TMV described by other workers: betweeri the mild green mosaic type and the dahlemense strain (WITTMANN-LIEBOLD and WirrmANN 1963, KNIGHT 1963), between the yellow mosaic type and the yellow tomato atypical mosaic virus (Y-TA MV) strain (KNI Gin. et al. 1962, KNIGHT 1963) and between the severe green mosaic type and the common tobacco mosaic virus (vulgare) strain (TsuGrrA 1962, KNIGHT 1963). The exact classification and nomenclature of TMV isolates/isolate groups as strains is possible and justified only after both their biological properties and their detailed chemical compo- sition, including the nucleotide and amino acid sequences are known. Aknowledgement. —Financial support is received from the Academy of Finland, Research Council for Agri- culture and Forestry. REFERENCES KNIGHT, C. A. 1963. Chemistry of viruses. Protoplasma- tologia IV, 2. 177 p. Wien. —, SILVA, D. M., DAHL, D. & Tsu GrrA, A. 1962. Two distinctive strains of tobacco mosaic virus. Virology 16: 236-243. LINNASALMI, A. 1966. Virus diseases of cucumber in Finland and characteristics of their causal agents cucumber mosaic and cucumber green mottle mosaic viruses. Ann. Agric. Fenn. 5: 305-323. & MURTOMAA, A. 1966. Virus diseases of tomato in Finland. I. Occurrence and causal agents of the diseases. Ann. Agric. Fenn. 5: 345-354. & RASHID, R. 1969. Base composition of ribonucleic acid in tobacco mosaic virus and potato virus X isolates from tomato. Finn. Chem. J. 42: 455-459. TSUGITA, A. 1962. The proteins of mutants of TMV: Classification of spontaneous and chemically evoked strains. J. Mol. Biol. 5: 293-300. WITTMANN-LIEROLD, B. & WITTMANN, H. G. 1963. Die primäre Proteinstruktur von Stämmen des Tabak- mosaikvirus. Aminosäuresequenzen des Proteins des Tabakmosaikvirusstammes dahlemense. Teil III. Z. Vererbungslehre 94: 427-435. Matuescrip received 17 lune 1980 Annikki Linnasalmi Agricultural Research Centre Institute of Plant Pathology SF-01300 Vantaa 30, Finland 258 SELOSTUS Tupakan mosaiikkivirus (TMV) -tyypit tomaatissa Suomessa ANNIKKI LINNASALMI Maatalouden tutkimuskeskus Tupakan mosaiikkivirusaineistossa (TMV) tomaatti- viljelmiltä Suomessa (v. 1962-65) erotettiin kolme pää- ryhmää, lievä viherkirjo-tyyppi, joka oli ylivoimaisesti yleisin (93 %) sekä keltakirjo (4 %) ja vahva viherkirjo (3 %) -tyypit, jotka esiintyivät vain sporaadisesti. Tyypit on karakterisoitu niiden symptomatologian nojalla to- maatissa (Lycopersicon esculentum Mill.) ja viidessä Nicoliana -testikasvissa (N. tabacum L. cv. Samsun ja cv. Xanthi, N. glutinosa L., N. rustica L. ja N. sylvestris L.) sekä niiden lämmönsietorajan, ribonukleiinihappoemäskoos- tumuksen ja aminohappokoostumuksen perusteella. Ana- lyysit tehtiin yhteensä 55:stä isolaatista. 259 CONTENTS MÄKELÄ, K. & MÄKI, L. The occurrence of micromycoflora in the stem base and roots of cereals in southern Finland 187 — & PARIKKA, P. Root and foot rot diseases in southern Finland in 1975-1978 223 LINNASALMI, A. Tobacco mosaic virus (TMV) types from tomato in Finland 254 ISSN 0570-1538 ' 260 ILASTON POHJAKARTTP M1,1 ,nrns, ''..•.. • INSTITUTES, EXPERIMENTAL STATIONS AND BUREAUS OF THE AGRICULTURAL RESEARCH CENTRE 1. Administrative Bureau, (HELSINKI) — 2. Institutes of Soil Science, Plant Pathology, Fest Investigation and Animal Breeding; Isotope Laboratory, Pesticide Regulation Unit, Computing Service, Library (VANTAA) — 3. Institutes of Plant Breeding, Agricultural Chemistry and Physics, Plant Husbandry, Animal Husbandry and Bureau for Local Experiments (JOKIOINEN) — 4. Insti- tute of Horticulture (PIIKKIÖ) — 5. South-West Exp. Sta. (MIETOINEN) — 6. Satakunta Exp. Sta. (KOKEMÄKI) —7. Sata-Häme Exp. Sta. (MOUHIJÄRVI) — 8. Häme Exp. Sta. (PÄLKÄNE) — 9. Kymenlaakso Exp. Sta. (ANJALA) — 10. South Savo Exp. Sta. (MIKKELI) — 11. Central Finland Exp. Sta. (LAUKAA) — 12. South-Pohjanmaa Exp. Sta. (YLISTARO) — 13. Karelia Exp. Sta. (TOHMAJÄRVI) — 14. North Savo Exp. Sta. (MAANINKA) — 15. Central Pohjan- maa Exp. Sta. (TOHOLAMPI) — 16. Kainuu Exp. Sta. (VAALA) — 17. North Pohjanmaa Exp. Sta. (RUUKKI) — 18. Lapland Exp. Sta. (ROVANIEMI) — 19. Swine Research Sta. (HYVINKÄÄ). SISÄLLYS — CONTENTS MÄKX/-Ä, K. & MÄKI, L. The occurrence of micromycoflora in the stern base ancl roots of cereals in southern Finland 187 Selostus: Viljan tyvissä ja juuristossa esiintyvä mikrosienistö Etelä-Suomen pelloilla 222 - - - & PARIKKA, P. Root and foot rot discases in southern Finland in 1975-1978 223 Selostus: Viljan tyvitautien esiintyminen Etelä-Suomessa vuosina 1975-1978 ,m LINKASALMI, A. Tobacco mosaic virus (TMV) types from tomato in Finland 254 Selostus: Tupakan mosaiikkivirus (TMV) -tyypit tomaatissa Suomessa 2.5° Ifelsinki 1981. Valtion painatuskeskw ISSN 0570-153R