| The purpose of this study was three fold; to analyze the effectiveness of various fungicides and initiation dates for calendar-based and weather-based spray programs for control of spinach white rust, to assess oospores as a source of primary inoculum for spinach white rust and to determine the activity of these fungicides at various periods after inoculation with conidia of Cercospora leaf spot. Field plots were treated with the fungicides according to a 7-day calendar program and a weather-based spray advisory program with an early, middle, and late initiation of the programs. The effects of fungicide, efficacy of spray programs and initiation dates on levels of white rust were evaluated. Oospores of the white rust pathogen were subjected to various treatments to encourage germination, and the resulting zoospores were inoculated to greenhouse plants to determine there pathogenicity. Fungicides were applied to greenhouse plants i day before, immediately before, and 1 to 5 days following inoculation of the plants with the secondary causal agent of the disease. (Abstract shortened by UMI.)... |
