Reduced yield potential and disease uncertainty make a fungicide investment in downed corn a risky proposition, university specialists from Iowa and Wisconsin say.
No-tillers considering a fungicide as a rescue application on lodged corn should save their money, according to university specialists.
“It’s a high-risk decision without much chance for a pay-off,” says Iowa State University plant pathologist Alison Robertson. “It really doesn’t make much sense regardless of the stage of growth. The chances a fungicide application breaking even is reduced in fields that have reduced yield potential.
“If you use fungicides, you should target fields with high yield potential. Do you really want to throw another $25 to $35 per acre at a crop that’s been damaged when you don’t really know that it will be beneficial?”
University of Wisconsin corn specialist Joe Lauer agrees.
“I don’t see any rescue value in applying a fungicide to lodged corn,” he says. “Whether or not a product like Headline will have any effect is very hard to predict. Generally, we don’t recommend a fungicide for hybrids with good disease resistance. A fungicide may be warranted on susceptible hybrids if disease is present but I don’t see any particular value for lodged corn.”
Robertson and Lauer both point out that diseases encouraged by wounding — like plant damage caused by wind or hail — are primarily bacterial infections such as Goss’s Wilt, smut and stalk rot. Most foliar fungal diseases like gray leaf spot, common rust and northern corn leaf blight do not require a wound in order to infect the plant.
No-tillers considering a fungicide as a rescue application on lodged corn should save their money, according to university specialists. (Photo courtesy of University of Nebraska)
Robertson adds that the prospects for a beneficial fungicide application may also be compromised by an inability to achieve thorough fungicide penetration into the wind-altered canopy.
Neither scientist is aware of any data regarding the effect of fungicides on lodged corn. Lauer does cite a simulated hail trial in Illinois that showed no advantage to fungicide applications.
The best approach is to apply some “patience” to a corn crop damaged by wind when the plants are still growing, he says.
“The ability of the crop to snake back up is a function of the amount of greenness on the plant,” Lauer says, explaining that wind-flattened green plants will normally grow upward with a curve in the lower stalk. “As long as the stalk is green, photosynthesis is occurring and the plant will recover to some degree.
“If the windstorm occurs at mid-season or before, you can see a lot of recovery. If the stalk has turned brown, though, the cells are dead and they will not respond.”
Wind lodging is most likely to occur in mid-vegetative stages when soils are saturated and brace roots have not fully developed, he adds
Lauer says no-tillers should be aware of the risk factors that make fields susceptible to lodging. In addition to genetic, biotic and environmental factors, the prospect of a good crop is another consideration.
“Especially watch those fields where you’re expecting high yields,” he concludes. “The ears themselves put a lot of torque on the stalk and that can certainly contribute to lodging.”