author(s)
Sairam K, Gopal K, Arunodhayam K, Ruth Ch, Ramaiah M and Nandini MLN

abstract
Purple leaf blotch of onion (Alternaria porri) is most devastating disease of onion in India and a challenge for producer is to find the effective means of control for this disease. As Fungal bio agents are also playing an important role in controlling the incidence of purple leaf blotch disease. An experiment was carried out in the Department of Plant Pathology, College of Horticulture, Anantharajupeta to isolate the causative agents of purple leaf blotch to study the effect of different fungal antagonists to control the disease in in vitro. The efficacy of 5 fungal antagonists viz, Trichoderma harzianum, Tichoderma viride, TCT4, TCT10 and Penicillium chrysogenum on growth of A. porri was studied in vitro by dual culture technique. The results revealed that the fungal antagonists significantly reduced the growth of the pathogen either by antibiosis (exhibiting inhibition zones) or competition (over growing). It was noticed that maximum reduction in colony growth of A. porri was observed in T. harzianum (54.84%) and significantly superior over all other bioagents tested and followed by T. viride (44.72%) and the next best was TCT4 (42.19%). Least inhibition was noticed in Penicillium chrysogenum (27.42%).