Refinement of Technology for the Management of Collar Rot in Apple

Collar rot in apple caused by Phytophthora cactorum is a major threat to the successful cultivation of crop. The incidence of disease is 13.27 per cent in Shimla and 8.31 per cent in Kinnaur districts of Himachal Pradesh. On farm trials for two consecutive years were conducted to assess and refine the existing technology for the management of the disease by integrating agrochemicals with Trichoderma viride which included three drenchings in rainy season with following treatments T1 [metalaxyl (8%) + mancozeb (64%) @0.5%], T2 [mancozeb (75%) @ 0.5%], T3 [Trichoderma viride @0.5%], T4 [one drenching with metalaxyl (8%) + mancozeb (64%) @0.5% followed by two drenchings with Trichoderma viride @0.5%], T5 [one drenching with mancozeb (75%) @ 0.5% followed by two drenchings with Trichoderma viride @0.5%] and T6 [Control/farmers’ practice]. Beside fungicide drenching, cultural practices were improved i.e. improvement in water drainage system in tree basin, opening of collar region of affected plant and removal of infected portion of roots with application of Chaubatia paste on open cuts. Among all the treatments, maximum percent lesion healing i.e. 37.65 per cent and 33.80 per cent in 1st year of treatment, 60.77 per cent and 55.60 per cent healing in second year of treatment was observed in plants drenched with T4 [one drenching with metalaxyl (8%) + mancozeb (64%) @0.5% followed by two drenchings with Trichoderma viride @0.5%] in Kinnaur and Shimla districts, respectively.