Biological control of Botrytis-incited diseases and powdery mildews in greenhouse crops

The greenhouse environment is very conducive to several diseases, among which grey mould and powdery mildews are the most important ones. Currently, much attention is given worldwide to the biological and integrated means of control of these two diseases, yielding reports on many potential antagonists. The two diseases differ greatly with respect to their epidemiology and the physiology of the pathogens. Hence, different approaches to their biocontrol are adopted. Biocontrol of powdery mildews is mostly based on the application of hyperparasitic fungi. In order to achieve a high level of parasitism, the biocontrol agents need a low vapour pressure deficit (VPD), compared to the VPD needed for the development of powdery mildews. Therefore, measures are necessary to overcome this problem. On the other hand, biocontrol of the high humidity-promoted Botrytis cinerea, is mostly based on saprophytes. The efficacy of biocontrol agents and their survival are dependent on biotic and abiotic factors. So far, results obtained under commercial conditions are rather moderate, but even so there are biocontrol agents suitable for integration with other control measures in order to achieve a control level acceptable to growers. Formulations of biocontrol agents against B. cinerea and powdery mildews have already been released and registered in some countries. They are only moderately effective but are suitable for use in integrated control of the target diseases. Copyright (C) 1996 Elsevier Science Ltd.