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Poster: Biology & Disease Mgmt: Integrated Pest Mgmt


Anthracnose impacts biomass and sugar yield of forage but not sweet sorghum
A. HAGAN (1), K. Bowen (1), H. Miller (1) (1) Auburn University, U.S.A.

Impact of anthracnose on aboveground dry matter (ADM), estimated sugar yield (SY), and total fermentable sugar concentration (°Bx) of energy feedstock forage and sweet sorghum is undefined. A factorial study with irrigated SS405 forage sorghum and Topper 76-6 (2014) or M81-E (2015) sweet sorghums as whole plots, and 1, 2, 3, 5, 6, or 7 (2014 only) broadcast applications of Headline (12 fl oz A-1) at 28, 35, 42, 49, 56, 64, and 72 DAP [days after planting] as the split-plot treatment was used. A non-fungicide treated control was included. Anthracnose intensity was recorded at 7 to 14 d intervals from 30 DAP until harvest at soft dough; areas under the disease progress curves (AUDPC) for anthracnose were calculated from these ratings. On SS405, anthracnose intensified from onset at 30 to 45 DAP through harvest at 111 DAP when > 75% leaf area loss was noted for all but the 6- or 7-application programs. While Topper 76-6 was anthracnose-free, this disease intensified on M81-E from onset at 90 DAP until harvest at 133 DAP when > 75% leaf area loss was observed for all Headline programs and the non-fungicide treated control. In 2015, anthracnose AUDPC increased as Headline application number declined on SS405 but not M81-E. AUDPC was regressed against ADM, SY, and °Bx. In both years, ADM, SY, and °Bx declined by up to 30% as anthracnose intensified on SS405. Headline application number did not impact ADM, SY, and °Bx of the disease-free Topper 76-6.