Integrated biological control of powdery mildew and grey mould of cucumber and tomato using Brevibacillus brevis combinations

Powdery mildew of cucumber caused by Sphaerotheca fusca and grey mould (Botrytis cinerea) of tomato, two important diseases of greenhouse crops, were tested for suppression of disease using integrated biological control. Brevibacillus brevis wild type (WT), a bacterial spore-former and well established biological control agent (BCA) with broad spectrum activity, was used as the main BCA for both disease systems. All agents were tested singly and in combination and also included: i) a plant extract of Reynoutria sachalinensis that induces resistance mainly against powdery mildew and ii) Pseudomonas antimicrobica, a non spore-forming bacterial BCA active against B. cinerea. B. brevis WT reduced disease by both fungal plant pathogens. Moreover, significant and heightened control of S. fusca was achieved using the B. brevis WT/R. sachalinensis combination in whole plant systems. Ps. antimicrobica also reduced disease incidence when tested using a detached tomato leaf bioassay system which was further enhanced, again significantly, when combined with B. brevis WT. These studies indicated that B. brevis is well suited to combination with other biological disease control agents to offer increased efficacy for integrated biological control.