Enhancement of biological control of Botrytis cinerea on cucumber by foliar sprays and bed potting mixes of Trichoderma harzianum YC459 and its application on tomato in the greenhouse

Abstract

Trichoderma harzianum YC459 (Th 459), isolated from sawdust compost, was effective in controlling cucumber and tomato gray mold caused by Botrytis cinerea under controlled and plastic film tunnel conditions. A water suspension of the wettable powder formulation of Th 459 significantly (P<0.05) reduced the severity of cucumber gray mold by foliar spraying at all tested concentrations from 105 to 108 colony forming unit (cfu)/ ml in repeated experiments. The control efficacy was maintained at least seven days with the average control value of 70% in cucumber pot tests. Mixing one to eight grams of the granular formulation (108 cfu/g dry weight) of Th 459 into one liter nursery potting mix at seeding also significantly (P≤0.05) reduced the severity of cucumber gray mold by suppression of lesion formation three weeks after treatment. Application of mixing granular formulation at seeding in combination with foliar spraying during cultivation provided a more significant reduction (P≤0.05) of cucumber gray mold than granule mixing or leaf spray alone. The foliar spraying of the formulated wettable powder of Th 459 significantly (P≤0.05) reduced the infection of tomato fruits by B. cinerea as effective as the chemical fungicide, dichlofluanid, in three plastic film tunnel experiment trials. It is suggested that effective control of gray mold of cucumber and tomato can be provided by both treatment of Th 459 into potting mix and foliar spray through induction of systemic resistance and direct inhibition of the pathogen. © The Korean Society of Plant Pathology.