Epidemiological studies on powdery mildew of pea under varying climatic conditions

Abstract:

Plant pathologists have long noted that powdery mildew of pea (Erysiphe pisi) thrives in dry, moderately warm weather — but the precise climatic thresholds governing epidemic onset in tropical India remain poorly defined. This research tracked powdery mildew progression on field pea (cv. Kashi Nandini) at two contrasting locations — Thrissur (Kerala, humid tropical) and Amarkantak (Madhya Pradesh, sub-humid highland) — over two rabi seasons (2020-21 and 2021-22). Disease severity was recorded weekly from first appearance to peak infection. Amarkantak consistently recorded higher terminal severity (64-67%) than Thrissur (58-61%), with faster epidemic build-up. Multiple regression analysis identified mean temperature (18-24 °C) and relative humidity below 65% as the strongest predictors of weekly disease increment. A predictive model (R² = 0.86) based on temperature, humidity, and rainfall explained 86% of the variation in percent disease index. Yield losses ranged from 18% at moderate severity to 37% at severe levels. These findings provide location-specific epidemiological data that can support disease forecasting and timely fungicide scheduling in pea-growing regions.