Study on compatibility of Trichoderma asperellum and fungicides for the development of environment friendly and cost-effective disease management strategies

Abstract

Chemical fungicides are regularly being used to combat plant pathogens successfully. The escalating concern over human health and environmental safety often put pressure on farmers to lessen the use of chemicals. One of the approaches to minimize the use of fungicides is to integrate it with biological control agents (BCA). Trichoderma species are well known for their biological control activity against many plant pathogens. Application of Trichoderma is being endorsed for the management of diseases of tropical tuber crops viz., collar rot of elephant foot yam, tuber rot of cassava, stem and root rot of cassava, yam anthracnose and taro leaf blight. For an effective disease management, the activity of bio control agent should not be stalled by the usage of fungicides. Trichoderma asperellum has been studied expansively as a BCA with results reliant on the specificity of the isolate. Present study was conducted at ICAR-Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram to study the sensitivity of T. asperellum isolate tovarious fungicides. Knowledge onthe compatibility of possible bio agents with regularly used and newer agrochemicals is vital for refining/developingan efficient integrated disease management programme. Effect of twelve fungicideson mycelial growth of Trichoderma was tested by adopting poison food technique. Fungicides were tested at different concentrations ranging from 3.125 ppm to 3200 ppm. The fungicides, Copper oxychloride 50%, Cymoxanil 8%+ Mancozeb 64%, Mefenoxam 4%+ Mancozeb 64% and Cymoxanil 22.1% +Famoxadone 16.6% were compatible with T. asperellumat their recommended concentration by not inhibiting the mycelial growth. WhereasCarbendazim 50%, Carbendazim 25% + Mancozeb 50%, Hexaconazole 5%, Difenoconazole 25% and Metalaxyl–M 3.3%+ Chlorothalonil 33.1% inhibited the mycelial growth of bioagent indicating their incompatibility. A progressive increase in percent inhibition of radial growth in the fungus was observed as the concentrations of fungicides increased. The results obtained from the present study will help in revisiting integrated disease management strategies by combining bioagent, Trichoderma and fungicides for managing fungal diseases of tropical tuber crops.