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POSTERS: Chemical control

Effectiveness of fungicide programs for control of potato early blight in Central Wisconsin, 2018
John Hammel - University of Wisconsin-Madison. Stephen Jordan- University of Wisconsin-Madison, Amanda Gevens- University of Wisconsin-Madison

Early blight caused by the fungus Alternaria solani is a perennial disease of potato (Solanum tuberosum) that affects potato production in Wisconsin. The disease can cause premature defoliation of susceptible cultivars, ultimately leading to losses in tuber quality and yield. Conventional potato growers in Wisconsin rely on routine fungicide applications for effective early blight control. There are many fungicides currently registered for managing early blight of potato in Wisconsin, with additional fungicides in various stages of development. Thus, we conducted a field trial with a randomized complete block design and 4 replications on ‘Russet Burbank’, an industry standard cultivar, at the UW-Hancock Agricultural Research Station to evaluate the effectiveness of 31 fungicide programs, including at-planting and weekly foliar treatments, for disease control. Early blight severity was assessed 6 times throughout the growing season using the Horsfall-Barratt rating scale. All data were analyzed using ANOVA (?=0.05) and Fisher’s LSD at ?=0.05. Compared to corresponding values of the non-treated control, 30 of the 31 treatments resulted in significantly less disease severity (measured by Relative Area Under the Disease Progress Curve values) and 6 resulted in significantly greater smaller-sized (‘B) tubers. Treatments including in-furrow applications of the fungicide fluopyram were shown to be the most effective in managing early blight. These results are useful to growers in designing disease control programs with consideration to fungicide resistance management.