Effect of Downy Mildew on Spacing and Different Host Range in Cucumber

Abstract

Downy mildew caused by Pseudoperonospora cubensis is one of the most destructive diseases of cucurbits worldwide. The present investigation was conducted to study the host range and effect of plant spacing on disease development in cucumber under field conditions. Eight cucurbit hosts, including watermelon, muskmelon, pumpkin, sponge gourd, ridge gourd, bottle gourd, bitter gourd and round gourd were evaluated for percent disease intensity (PDI). The pathogen infected all tested hosts, with muskmelon showing the highest disease intensity throughout the observation period, while pumpkin recorded the lowest PDI. A separate experiment assessed six plant spacings in cucumber to determine their influence on disease severity and yield. Narrow spacing (1.0 m × 1.0 m) recorded the highest PDI but also produced maximum yield, whereas wider spacing (2.0 m × 1.0 m) significantly reduced disease intensity with comparatively lower yield. The study revealed a negative correlation between plant spacing and disease development. These findings highlight the importance of host susceptibility and optimum plant spacing in managing downy mildew in cucurbits.