EFFICACY OF BIO-INOCULANTS AND NEW GENERATION FUNGICIDES FOR THE MANAGEMENT OF TWISTER BLIGHT OF ONION CAUSED BY COLLETOTRICHUM GLOEOSPORIOIDES

Abstract

Onion (Allium cepa L.) is an important vegetable crop worldwide and has great economic importance because of its nutritional and medicinal values. Among the diseases, the anthracnose-twister blight plays a vital role in its low productivity which at present is considered to be the most destructive disease of onion in the country. The chemical control based on the use of fungicides is most effective and reliable method. New fungicides with novel chemistry are being introduced and evaluated for plant disease control. The present study was carried out to formulate integrated approach by combining newer chemical with biocontrol agents.Native isolates of Twister blight of onion caused by Colletotrichum gloeosporioides was collected from onion growing areas of Pullambadi block of Trichy district. For in vitro screening Bacillus subtilis (Bbv57)and Trichoderma asperellum (TNAU Tv1) was used as per the recommendation along with Pyraclostrobin, Fusilazole, Azoxystrobin and Metiram along with Copper oxychloride as chemical check.Efficacy of different fungicides viz., Pyraclostrobin0.1%, Fusilazole 0.1%, Azoxystrobin 0.1%, Metiram 0.1 % along with Copper oxychloride 0.25 % was evaluated against Colletotrichum gloeosporioides causing twister blight of onion using poisoned food technique. Among the new generation fungicides tested, Fusilazole 0.1% showed cent percent inhibition of mycelial growth and copper oxy chloride recorded highest inhibition of 74.11% mycelial growth and was significantly superior over all other treatments. Pyraclostrobin, Azoxystrobin and Metiram (systemic fungicides) recorded partial inhibition of mycelial growth of 68.6 %, 7.40 % and 55.6% respectively. In dual culture technique the efficacy of Bacillus subtilis (Bbv57) and Trichoderma asperellum (TNAU Tv1) was studied. Among the two Trichoderma asperellum (TNAU Tv1) exhibited 100 % inhibition and parasitization of Colletotrichum gloeosporioides whereas Bacillus subtilis (Bbv57) exhibited 93.85 % inhibition over control.