The effects of biological and chemical treatment on gray mold disease in tomatoes grown under greenhouse conditions

Abstract

A total of 163 bacterial strains isolated from tomato leaves were evaluated for their ability to suppress gray mold (Botrytis cinerea Pers. ex Fr.) on tomatoes, and 4 strains consistently reduced the incidence of B. cinerea. These antagonist strains were identified as Pseudomonas fluorescens. The bacterial strains with in vitro resistance to fungicides were combined with low-dose fenhexamid in vivo. One strain of P. fluorescens (Pf 163) reduced the disease incidence by an average of 78% on tomato plants inoculated with B. cinerea in greenhouse trials. In comparison to the control treatment, other P. fluorescens strains applied with low-dose fenhexamid reduced the incidence of decay by 74.17%, 70.52%, and 65.74%, respectively. The antagonists significantly reduced gray mold decay when combined with low-dose (12.5 ml a.i. hl(-1)) fenhexamid more than the control did. It was shown that antagonistic bacterial strains inhibited B. cinerea and that they have a potential use in combination with the fungicide in greenhouse experiments.