Fungicide Applied on High-Yield Plots Last Week

Timing depends upon growth stage, not calendar.

Published on: Aug 11, 2008

One farm manager a few days ago commented he thought he waited two weeks too long to order fungicide applied on farms where he thought it was necessary. After all, he reasoned, surely he should have applied it before August.

Not necessarily, says Dave Nanda, plant breeder and consultant for Corn Illustrated. The fungicide application on the Corn Illustrated high-yield plot near Edinburgh, Ind., was made on August 4. And it wasn't delayed by weather or any other factor. The application was made exactly when Nanda, working with Jim Facemire, the farmer involved in the project, scheduled it.

"Nanda told me he wanted at least 90% of the plants silking before we made the application," Facemire says. When he thought that point was in the bullseye, he pulled the trigger. The plot was ground- applied with a high-clearance rig by a the Shelby County Co-op. An experienced custom applicator made the application. Quadris was the product selected this year.

Why was the corn so late in tasseling? "It wasn't planted until the last week of May, then we've run behind on heat units," Nanda says. "So it's running behind on maturity."

Another cooler-than-normal week developed there last week, continuing through today, August 11. The good side of that is cool temperatures during pollination favor higher yield. The down side is that it also delays maturity and will likely make for wetter corn at harvest.

For the first time all season, moisture levels dipped low enough that Facemire fired up the irrigation rig and irrigated the high-yield plot about 10 days ago. Then on Aug. 5, the day after the fungicide application, his rain gauge collected 2.5 inches, continuing the complete reversal from last season's hot, dry summer.

The temperature was predicted to reach 93 degrees F in Indianapolis, about 30 miles north that day. But with the rains, it toped out about 76 degrees instead. So far there have only been a handful of 90 degree or higher days this summer, well below average. Last summer this stretch in August was some of the hottest, most brutal, dry weather of the season. Corn planted when this year's plots were planted, except for the population plant, simply melted after standing all the heat and dry weather it could take. It doesn't appear that will be the case this time.

Did the plots really need the fungicide application? "There was quite a bit of stuff out there," Facemire says, referring to disease lesions on leaves. Working with Nanda for the past several years on plots, he's developed a keen eye for foliar diseases in corn.