MANAGEMENT OF LATE BLIGHT OF POTATO CAUSED BY PHYTOPHTHORA INFESTANS THROUGH BOTANICAL AQUEOUS EXTRACTS

Abstract

Late blight caused by Phytophthora infestans (Mont.) de Bary is most devastating pathogen of potato crop. Disease caused Ireland's worst devastation during 1840– 1845 and since then, it has caused considerable yield losses globally. The repeated and injudicious synthetic fungicide applications against late blight developed fungicide resistance in P. infestans have given a push to finding out alternate ways to control the disease. The study was carried out to evaluate the efficacy of garlic (Allium sativum), neem (Azadirachta indica), turmeric (Curcuma longa), mint (Mentha) at 5, 10 and 15% concentrations as bio-fungicides against late blight of potato. In-vitro effect of aqueous plant extracts was evaluated on percent inhibition and radial growth of pathogen. In comparison to the control, A. sativum and A. indica at 15% concentration were found to be more effective in inhibiting P. infestans mycelial growth by 58.4% and 43.9%, respectively. In the greenhouse trials, overall potato late blight disease incidence was minimum (5.81%) where A. sativum extract was used followed by A. indica (8.45%) at 15% concentration as compared to control (61.18%). Similarly, 15% aqueous extracts of A. sativum was found highly effective with 15.4% disease severity, as compared to control (54.13%). The use of A. sativum and A. indica aqueous plant extracts at a concentration of 30% was found to be the most promising and effective measure against the late blight pathogen. Study provides a comparison of environment friendly botanical extract based disease control for organic vegetable production opportunity inspite of health hazardous synthetic agro-chemicals.