In many parts of the world, including the Great Lakes region of the United States, Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is a major foliar disease of sugar beet (Beta vulgaris subsp. vulgaris). CLS management has become challenging in recent years due, in part, to an increase in fungicide resistance. If CLS is to be successfully managed in the future, more information about its epidemiology and alternative management strategies will be necessary. Thus, my first study employed sentinel beets to detect C. beticola spores in the field during the first half of the growing season. In both years of the study, spores were detected earlier than any previous reports. The spore levels detected fluctuated during both seasons and were correlated with factors such as rainfall and relative humidity. This information could be used to improve the timing of fungicide applications. The second study examined the potential of bicarbonate salts to be used as fungicides for C. beticola management. Ammonium, potassium, and sodium bicarbonate were tested in vitro. Each inhibited the growth of C. beticola, with ammonium bicarbonate causing complete growth inhibition at 1% (w/v). Sodium bicarbonate at 2% (w/v) significantly reduced CLS in the greenhouse compared to a control, so it might be useful in the field. The third study tested the effects of heat treatment in the form of a propane torch on C. beticola in vivo, with the goal of using such a technique to reduce inoculum levels of the fungus. Heat treatment of infected leaves completely inhibited sporulation and decreased fungal viability by over 80%. The new insights and methods developed from this research have the potential to aid in future CLS management.
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