Figure 5.
In vitro testing for P. viticola based on leaf disc bioassay (A), zoospore microtiter plates (B), and oospore testing (C). (A) microtiter plate containing leaf discs showing white sporulation (WS). Columns were treated with increasing concentrations of fungicide. (B) Sporangium (S) and free zoospore (Z) in liquid medium. (C) Agar plates containing increasing concentrations of fungicides and inoculated with oospore suspensions. The number of germinated oospores (GO) is counted and used to calculate the germination percentages at each concentration and to estimate the EC50 values of the population or the percentage of resistant oospores at a discriminatory concentration of fungicide.