Evaluation of fungicides and application timings for management of sorghum anthracnose in the mid-Atlantic region of the U.S.
Bhupendra Acharya: Virginia Tech
<div>Demand for locally sourced animal feed has increased grain sorghum production in the mid-Atlantic. Sorghum anthracnose (<em>Colletotrichum sublineola</em>) reduces grain yield up to 50%, but management recommendations have not been developed for the mid-Atlantic where warm, wet conditions favor disease. Using a 6x4 factorial design, five fungicides (Priaxor, Headline, Quadris, Aproach, Tilt) and four application timings (single applications at boot, flowering, or 14 days after flowering; and applications at all three timings) were compared for anthracnose control and yield response in sorghum over 10 site-years in VA and NC from 2015-2017. Anthracnose severity was rated biweekly, and grain yield was determined at harvest. Effects of fungicide, timing, site-year and their interactions were significant (P<0.0001). Disease onset and final severity varied among locations. Priaxor and Headline reduced anthracnose, and three applications resulted in significantly lower disease and higher yield compared to single applications. For single applications, flowering timing provided the most consistent reductions in anthracnose compared to the untreated control. Pyraclostrobin is an active ingredient in Priaxor and Headline, and in in-vitro fungicide sensitivity tests, this fungicide was the most effective for inhibiting <em>C. sublineola</em> growth. Results indicate a single well-timed application of a pyraclostrobin-containing fungicide controls anthracnose and protects sorghum grain yield.</div>
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