Use of kaolin clay for disease control in greenhouse cucumbers

Elizabeth M. Lamb, Erin N. Rosskopf, Chip Koblegard


Greenhouse vegetables have a high value in the marketplace and consequently consumers have a low tolerance for imperfections. Diseases can be a limiting factor in the high temperature and relative humidity environment of a greenhouse. Because greenhouse vegetables are a relatively small pesticide market, there are few chemical compounds labeled for use in greenhouse production. Foliar applications of clays, such as kaolin, have been suggested as a method of reducing fungal diseases by interfering with the ability of the fungus to penetrate the leaf surface. Foliar kaolin sprays and a phosphite foliar fertilizer (Ele-Max) were compared to current standard chemical sprays for control of downy mildew and gummy stem blight on European cucumbers in a commercial greenhouse. Alternative disease treatments were comparable to the conventional spray program in controlling disease. However, Ele-Max-treated plants had significantly lower yields than all other treatments.


cucumis sativus; didymella bryoniae; downy mildew; gummy stem blight; phosphite; pseudoperonospora cubensis

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283