BIOCONTROL OF LETTUCE DROP CAUSED BY BIOCONTROL OF LETTUCE DROP CAUSED BY BIOCONTROL OF LETTUCE DROP CAUSED BY SCLEROTINIA SCLEROTIORUM UNDER PROTECTED CONDITIONS UNDER PROTECTED CONDITION

Abstract

Lettuce (Lactuca sativa L.), belonging to family Asteraceae, is one of the popular green leafy-vegetables. Among various diseases attacking this crop, lettuce drop caused by Sclerotinia sclerotiorum is the most destructive disease. Considering the more concern over pesticide residues on this crop, effect of fungal and bacterial biological control agents on incidence of lettuce drop was studied. Out of fungal antagonists, T. harzianum was found most effective (65.26%) in inhibiting the test pathogen followed by T. viride (60.94%), T. hamatum (60.69%) and T. polysporum (59.76%), while bacterial antagonists (Bacillus subtilis and Pseudomonas fluorescens) did not inhibit the pathogen significantly under in vitro conditions. T. harzianum also resulted in minimum incidence (14.44%) of lettuce drop followed by T. viride under in vivo conditions. An experiment conducted under protected conditions revealed minimum incidence of lettuce drop by T. harzianum giving more than sixty per cent reduction in disease over control and highest yield of lettuce head followed by T. viride. Therefore, T. harzianum can be used effectively in minimizing the incidence of lettuce drop under protected conditions