Late Blight of Potato (Phytophthora Infestans) Management through Botanical Aqueous Extracts in Temperate Climatic Conditions

Phytophthora infestans causing late blight is one of the most devastating tomato and potato disease that caused considerable yield losses globally including Pakistan. Due to repeated and injudicious synthetic fungicides applications for the control of late blight of potato, the fungicide resistance in P. infestans led to persistence and surveillance late blight of potato. The study was carried out to evaluate the efficacy of Garlic (Allium sativum), Neem (Azadirachta indica), Turmeric (Curcuma longa), Mint (Mentha) at 10%, 20% and 30% concentration as bio-fungicides against late blight of potato. In-vitro effect of plant extracts of A. sativum, A. indica, C. longa and Mentha were evaluated on percent inhibition and radial growth of pathogen. A. sativum and A. indica at 30% concentration was found more effective in minimizing the mycelial growth of P. infestans with inhibition of 58.4% and 43.9% respectively as compared to control. In the greenhouse trial, overall potato late blight disease incidence was minimum 5.81% where A. sativum extract was  used followed by A. indica at 30% concentration resulted 8.45% incidence as compared to control 61.18%. Furthermore, the 30% aqueous extracts of A. sativum  found highly effective against late blight disease with 15.4% severity,  as compared to control with 54.13% disease coverage. Application of A. sativum and A. indica aqueous plant extracts with a concentration of 30% was found most promising and effective measure against late blight pathogen. Study provides environmentally benign mileage in organic vegetable production against hazardous synthetic agro-chemicals.