Study on powdery mildew of cucumber caused by Erysiphe cichoracearum

Abstract:

Powdery mildew, caused by Erysiphe cichoracearum, severely damages tropical and temperate cucumber crops, inducing chlorosis, defoliation, and reduced photosynthesis. To map regional distribution and infection hotspots in southern Rajasthan, a systematic roving survey was conducted across Udaipur, Chittaurgarh, and Banswara districts during the 2024–25 cropping season. Micro-regional sampling spanned nine agricultural blocks: Bargaon, Bhinder, and Girwa (Udaipur); Barisadri, Begun, and Bhadesar (Chittaurgarh); and Anandpuri, Arthuna, and Garhi (Banswara). Fungal expression was evaluated at multiple growth stages using Percent Disease Incidence and Percent Disease Index (PDI) via a 1–9 visual leaf-coverage scale. The regional mean disease incidence reached 48.65% with a severity of 40.85 PDI. Banswara emerged as the primary hotspot (55.90% incidence, 47.85 PDI), with peak damage in Anandpuri and Garhi due to high humidity. Chittaurgarh showed moderate infection (48.25% incidence, 40.10 PDI), spiking in Barisadri during reproductive stages. Udaipur recorded the lowest baseline values (41.80% incidence, 34.60 PDI), particularly in early-planted Bargaon fields. Because incidence exceeded severity, local microclimates and farming practices clearly altered infection levels. These baseline data are vital for building localized forecasting tools, timing chemical sprays, and launching resistance breeding programs.