Biological control in greenhouse systems

The controlled environment of greenhouses, the high value of the crops, and the limited number of registered fungicides offer a unique niche for the b iological control of plant diseases. During the past ten years, over 80 bio control products have been marketed worldwide. A large percentage of these have been developed for greenhouse crops. Products to control soilbome path ogens such as Sclerotinia, Pythium, Rhizoctonia and Fusarium include Coniot hyrium minitans, species of Gliocladium, Trichoderma, Streptomyces, and Bac illus, and nonpathogenic Fusarium. Products containing Trichoderma, Ampelom yces quisqualis, Bacillus, and Ulocladium are being developed to control th e primary foliar diseases, Botrytis and powdery mildew. The development of Pseudomonas for the control of Pythium diseases in hydroponics and Pseudozy ma flocculosa for the control of powdery mildew by two Canadian research pr ograms is presented. In the future, biological control of diseases in green houses could predominate over chemical pesticides, in the same way that bio logical control of greenhouse insects predominates in the United Kingdom. T he limitations in formulation, registration, and commercialization are disc ussed, along with suggested future research priorities.