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Poster Session: Biology and Disease Management - Chemical Control


Effect of Pyraclostrobin spray either solo or in combination with other chemicals on soybean diseases and yield response in Iowa from 2003 to 2013.
S. NAVI (1), X. Yang (2), X. Li (2), L. Jing (3)
(1) Iowa State Univ, Ames, IA, U.S.A.; (2) iowa state university, ames, IA, U.S.A.; (3) Inner Mongolia Agricultural University, Hohhot, China

Twenty eight fungicide trials were set up in a RCBD with four replications each with 3-m wide (four 76-cm rows) × 13.8-m long plots in multiple locations of Iowa State University Research farms, from 2003 to 2013. Test products Pyraclostrobin (Headline®) alone or combination with insecticides and other fungicides were sprayed using CO2 backpack 3-m hand boom/ XR8003 tips. Pre- and post- spray disease ratings were recorded weekly from one week before spray through one week before the harvest. Plots were harvested using a John Deere 4420 combine and yields were measured in bu/ac converted to 13% grain moisture. Major diseases assessed were septoria brown spot (SBS), frogeye leaf spot (FELS), sudden death syndrome (SDS) and sclerotinia stem rot or white mold (WM). Headline, either solo or in combination with insecticides (1 out of 5 at a time) and other fungicides (1 or >1 of 12) showed significant (P<0.05) yield advantages over unsprayed controls across 18 roundup ready soybean varieties. Also, results showed wide-ranging yield advantages of sprays among varieties. Headline (solo or combination) significantly (P<0.05) suppressed SBS, and FELS. Across 11 seasons, average yield advantage was 5 bu/ac (range 2 to 8 bu/ac), even under low diseases pressure. Although no significant advantage of Headline (solo or combination) in plots with SDS and WM, but significant (P<0.05) yield increase was observed over unsprayed controls indicating plant health benefits of spray(s).