Comparative evaluation of fungal diseases in cucumber across growth stages and cropping seasons

Abstract:

A field investigation was conducted to assess seasonal patterns of fungal disease incidence in cucumber across the Kharif, Rabi, and Zaid seasons. The experiment included twelve cucumber hybrids grown under natural epiphytotic conditions without fungicide application to monitor disease development. Four major fungal diseases, viz., Fusarium wilt, powdery mildew, downy mildew, and gummy stem blight, were analysed at four distinct growth stages: vegetative, reproductive, fruiting, and harvesting. Disease incidence (DI) and Area Under Disease Progress Curve (AUDPC) were recorded to assess seasonal disease pressure and to quantify cumulative disease development. During the Kharif, downy mildew showed the highest DI at harvest (74.44%), followed by gummy stem blight (40.00%) and powdery mildew (39.16%). In Rabi, downy mildew remained predominant (66.11%), followed by powdery mildew (55.83%). Conversely, the Zaid season recorded the highest overall disease pressure, driven by powdery mildew (57.08%) and fusarium wilt (36.11%), while in the later stages by downy mildew (42.92%). AUDPC analysis revealed marked seasonal variation in cumulative disease development. downy mildew recorded the highest AUDPC in Kharif-2023 (1831.20) and Rabi-2023 (1685.32), whereas powdery mildew dominated in Zaid-2024 (1471.80), followed by fusarium wilt (858.22). This study highlights a significant increase in the prevalence of fungal pathogens across different growth stages and seasons in cucumber, providing baseline information on disease dynamics under natural epiphytotic conditions.