By LINDA McGURK
Indiana Correspondent

COVINGTON, Ind. — Farmers sprayed a record number of corn acres with fungicides in 2007, but was it money well spent? Not necessarily, according to Suzanne Bissonnette, an extension educator with the University of Illinois.

“There are situations when a timely fungicide application will save you,” she said during a Dec. 2 crop management and market outlook workshop in Covington, Ind., “but in a very low disease environment, a fungicide application does not give a good return.”
Last year, farmers in Illinois applied fungicides on 3-4 million acres, or 20-30 percent of the total corn acres. For the Midwest, the figure was 10-14 million acres. To make a fungicide application worthwhile, Bissonnette said yields need to increase by about 6 bushels per acre.

But, trials have shown that applications in the low-disease environment we’ve seen the past few years only produce a 3.5- or 4-bushel increase in yield.

“You need to ask yourself if you’re spending money when you don’t need to, or don’t (spend it) when you should have,” Bissonnette told more than 100 grain producers at the workshop.

A 2007 fungicide trial including 168 locations showed that spraying only resulted in a yield increase of 6 bushels or more in 63 locations, or 38 percent of the time. The mean increase for treated fields over untreated fields was 3 bushels per acre, assuming the fungicide was applied by ground at a cost of $20 per acre and a corn price of $3.50 per bushel.

Likewise, a 2006 foliar fungicide trial that compared untreated fields with those treated with Headline and Quilt didn’t find any significant differences in yield, with the exception of one hybrid. A 2008 study showed that a field treated with Headline had a mean gain of only 2.7 bushels per acre over an untreated field.

“(The results) have been really consistent from year to year,” Bissonnette said, adding that results from this year’s trials are still coming in. “We expect it to change a little this year, since we had a little change in fuel costs.”

She also gave an update on soybean rust, a disease growers need to keep an eye on, even if it didn’t move up to Illinois until October this year. “I get a little worried about next season when I see these huge amounts of rust,” Bissonnette said, pointing to a map showing severe soybean rust infestations in the South.

“It’s gotten more endemic in the southern states, and I wish I knew what that means to us. We need to be aware of it.”

Bissonnette said fungicide applications to soybeans are on the rise, and she cautioned against overzealous use. Aside from being a waste of money, applying too much fungicide can cause resistance and wipe out beneficial fungi – for example, those controlling aphid populations.

“We have some excellent fungicides, but they’re only as good as the amount of disease you’ve got out there,” she said.

The seminar was sponsored by Bi-State Agricultural Programs, a collaboration between the extension services of Purdue University and the UoI.