Impact of pre-harvest UVC treatment on powdery mildew infection and strawberry quality in tunnel production in Nordic conditions

Abstract

Preharvest UVC radiation treatment has emerged as a promising alternative to chemical plant protection methods in plant production systems for preventing fungal diseases. In our study, three strawberry (Fragaria x ananassa) cultivars were subjected to nightly UVC treatment (20 s, 0.02 kJ/m²) delivered through LED technology (with a peak at 276 nm) within polytunnel conditions in Central Finland. The aim was to evaluate the effectiveness of the UVC treatment in inhibiting powdery mildew (caused by Podosphaera spp.), as well as to assess its impact on crop yield, fruit quality, firmness, volatile organic compound (VOC) profile, and leaf properties across two consecutive growing seasons. The UVC treatment successfully suppressed the growth of powdery mildew in all three tested strawberry cultivars throughout the experiment, without causing any visible damage to the leaves. The UVC treatment led to an increase in the crop yield of marketable fruits without affecting their size. The impact on fruit quality varied, depending on the specific cultivar, sampling time, and the year under consideration. Fruit firmness following 2–3 days of refrigeration improved due to the UVC treatment. Our findings suggest that UVC treatment can alter the fruit's VOC profile, either directly or indirectly through disease management, affecting its aroma. These findings emphasize the diverse advantages of UVC treatment in enhancing disease resistance and enhancing specific fruit attributes. This suggests the potential for integration of UVC treatment into plant production systems, particularly in tunnel cultivation within Nordic conditions, as a promising approach to improve overall crop management strategies.