Biological Control of Botrytis cinerea in Tomato

B. cinerea infects tomato plants in heated greenhouses mainly through stem wounds caused by breaking or cutting off leaves, a general procedure in tomato plant maintenance. Such an infection can cause an entire plant to die, which can result in high yield losses. Sanitation and cultural measures can be part of the solution, but resistant cultivars are not present and chemical control only has a good efficacy when it is applied preventively. A lot of growers frequently use this preventive control. This is not a sustainable control method as B. cinerea has been shown to develop resistance against certain fungicides. As a consequence, there is a growing demand for biological treatment of grey mold diseases, including the use of specific biocontrol agents (BCAs). We previously isolated a fungal BCA from B. cinerea infected tomato plants. This fungus, designated as BCA1, exhibits a strong in vitro antagonistic and mycoparasitic effect against different B. cinerea isolates and other plant pathogenic fungi. In planta experiments on laboratory scale also showed a positive effect of preventive as well as curative application of BCA1 on artificial B. cinerea infections. Large scale experiments in a professional tomato greenhouse were performed to further explore its potential biocontrol effect against grey mould disease. The preventive treatment of stem wounds on tomato plants with a BCA1 spore suspension has been shown to be highly effective against B. cinerea. The B. cinerea infection rate drops with almost 90% when BCA1 spores are applied. In another experiment naturally occurring B. cinerea infections on tomato stem wounds, were treated with a simple coating with BCA1 spores. Over 30% of these wounds are stopped by this treatment, whereas the other infections are slowed down drastically.