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.