EN
Insecticides most often inhibit the development of fungal diseases, but can also stimulate them. The mechanisms of these phenomena are discussed and examples are given. The protective effect may be the result of direct pesticide influence on the pathogen, host susceptibility or other biocenotical components. The important factor is pest control which limits the infection of plants through the wounds caused by insects. Knowledge of side effect of insecticides on plant diseases may have important role during the application of pesticide mixtures and enable its usage in integrated plant disease control.