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2010 APS Annual Meeting


Effect of foliar fungicides on hail damaged corn in Wisconsin in 2009
P. D. ESKER (1), N. C. Koval (1)
(1) University of Wisconsin, Madison, WI, U.S.A.
Phytopathology 100:S34

On 24 July 2009, two trials located at Lancaster, WI were impacted by 0.6 to 1.3 cm-sized hail. In both trials, plants were at the tasseling into silking growth stages. The first trial was established to study the effect of fungicide timing (V5-V6, R1, or combinations) on corn disease development (all diseases) and yield and the second to study the effect of corn hybrid (n = 6) and fungicide on corn anthracnose and grain yield. Both trials had four replications. Trials were sprayed on 29 July at R1. In the first trial, fungicides included pyraclostrobin, azoxystrobin+propiconazole, and propiconazole+trifloxystrobin. Only pyraclostrobin was applied in trial two. Late season disease measures included early evidence of ear rot, top dieback, lodging due to anthracnose, and common smut. Corn plants (n = 5) were also destructively sampled for stalk assessments (0–5 rating scale). Yield measures were moisture, test weight, and grain yield (adjusted to 15.5% moisture). In trial one, there was no evidence of a difference among treatments (P > 0.05) for late season diseases or yield. Grain yield ranged from 93 to 141 bushels per acre (CV = 25.1%) and the increased variability was attributed to hail. In trial two, there were differences among treatments (P < 0.05), but these were primarily a function of corn hybrid and no differences in yield were observed. These results suggest that hybrid selection is still the primary factor to consider for corn disease management.

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