Fungicide Over the Top
By Steve Fairchild

High corn prices help introduce fungicide use on No. 2 yellow corn.

Among growers of seed corn or other high-value corn crops, well-timed fungicide treatments are common. Now, with corn prices on the rise and the promise of more corn-after-corn rotations, researchers and agronomists are looking at the value of a fungicide treatment on No. 2 yellow corn.

Jim Bloomberg, a product development manager for Bayer CropScience, said interest in fungicide application has grown with corn demand.

“In the past, No. 2 yellow corn didn’t have the margins to support it, but the ethanol market has started to drive prices to a level that makes a fungicide application economical,” said Bloomberg.

Interest has been mutual with growers making inquiries and crop protection companies launching new studies to see what economic benefits fungicides might have for commodity corn.

“There are numerous fungal diseases in corn,” Bloomberg said. “But rust and gray leaf spot are prominent. You can commonly find these in many fields across the Corn Belt.”

Bloomberg explained that Stratego, a fungicide from Bayer, works a couple ways on a corn crop. With a combination of strobilurin (trifloxystrobin), which fights fungus on leaf, plus the systemic fungicide propiconazole, Stratego is considered both curative and preventative. This list isn’t intended to be inclusive, but other fungicides labeled for corn include Headline from BASF and Syngenta’s Quadris and Quilt. Check company Web sites or your local MFA Agri Services to see which formulation fits your needs.

According to Bloomberg, Bayer field studies with a 10-ounce rate of Stratego have shown an average 10.7 bushels per acre increase over the past 3 years over a broad spectrum of environmental situations.

There are claims of such significant yield response from universities and fungicide sellers across the Corn Belt. A survey of press releases and news stories showed claims from a few bushels per acre to the mid -20-bushel range.

MFA agronomist Paul Tracy said that yield response will vary greatly depending on the environmental situation of each cornfield.

“Due to the possibility of producing fungicide-resistant diseases, I wouldn’t give a blanket recommendation for fungicide application on corn. But there are situations where it makes sense. In high-population scenarios, in fields with center-pivot irrigation and especially in corn-after-corn rotations where the disease inoculum has had a chance to build for more than one season, fungicide application can make sense.”

Bloomberg acknowledged the possibility for resistance and stressed that any disease management program should factor in the possibility of speeding resistance of fungicides.

Tracy also said understanding the genetics of the varieties you choose is important. Growers should closely study the strengths and weaknesses of the varieties they grow as they consider fungicide application. Some varieties could show signs of fungal diseases but not reach economic thresholds due to the plants’ disease resistance traits. A densely planted racehorse variety under the damp conditions of a center pivot on the other hand might well have suffered economic damage by the time the first fungal lesions are spotted.

So timing is everything.

“The best timing is around early tassel to a little later,” said Bloomberg. “You want to protect the ear leaf.”

Scouting is essential to alert growers of fungus legions. Again, watching the ear leaf and leaves just below is critical.

Of course, a fungicide treatment near corn means hiring an aerial applicator. That’s not an easy find in many of the marginal areas of the Corn Belt.

“In most years corn can be planted across the United States in 10 to 12 days,” said Bloomberg, pointing out that even if there are local air services available, a trend toward fungicide use on corn could cause a run on pilots. That could affect application timing. But he said there seem to be ancillary benefits to fungicide-treated corn. Bloomberg said that treated corn tends to appear greener in color due to something called a “greening effect,” a situation caused by a number of factors that reduce stress on corn as it is growing.

Bottom line is to consider your corn environment, yield goal and the price to get fungicide over the top of corn in a timely manner. If the numbers align positively, and you can find an aerial applicator, this might be the year to experiment.

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