BIOLOGICAL METHOD USED FOR EVALUATING THE HOP QUALITY TREATMENT AGAINST DOWNY MILDEW OF HOPS

Hop is a demanding crop as far as the protection against diseases and pests is concerned. Therefore it is necessary to use objective metod in evaluating pesticides applied. They are of special importance in testing new machines and recommendations for hop protection. A biological method was prepared for exact evaluation. This enables to determine exactly fungistatical effectiveness of protecting treatment using the microscope slide fixed on hop leaves before its treatment. The slides which are removed after drying the spraying liquid are dropped with zoosporange suspension of downy mildew of hops in the laboratory and the degree of suppression and release of zoospores is evaluated in comparison with untreated control. The method mentioned is used to test three new mist sprayers of domestic and foreign production. The results of tests for self-propelled mist sprayer, the Mistral 2000 type, and mounted mist sprayer Monzun 1540 were found to be good and are well applied in practice. The Zeros 1000 mounted mist sprayer failed in tests and found no further application in hop growing.