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Poster: Biology & Disease Mgmt: Integrated Pest Mgmt


Managing Rhizoctonia crown and root rot of sugar beets utilizing azoxystrobin-alternative fungicides in Nebraska.
R. HARVESON (1), R. Harveson (2) (1) University of Nebraska Panhandle Research & Extension Center, U.S.A.; (2) University of Nebraska Panhandle REC, U.S.A.

In Nebraska, Rhizoctonia root and crown rot, caused by Rhizoctonia solani, is generally considered to be the most commonly occurring and damaging sugar beet disease. Previous studies have demonstrated that applications of azoxystrobin will effectively reduce disease and improve yield parameters. However, the almost exclusive use of Quadris (azoxystrobin) for more than a decade raises concern for resistance development by the pathogen to this fungicide. Studies were conducted from 2013-2015 to evaluate the performance of alternative fungicides currently registered for this disease in sugar beets (Priaxor, Proline, Headline, and Vertisan) and compare their performance to Quadris. The study consisted of 16 treatments: 1) untreated control, 2-6) applications applied in-furrow at planting, 6-10) foliar applications after 4 inch soil temperatures averaged 65° F for three consecutive days, and 11-15) both in-furrow and foliar applications. Data collected included multiple disease counts during the season, and sucrose and root yield determinations at harvest. Our results indicated that Quadris, Priaxor, and Proline all performed similarly, significantly reducing disease incidence and increasing sugar yields compared with untreated controls. We further determined that better results were obtained with the combination of in-furrow and foliar applications later in the season than either treatment alone.