Growers can see a yield increase of 3 bushels per acre when using foliar fungicides on soybean fields where foliar diseases are present. Experts at Pioneer Hi-Bred, a DuPont business, say foliar fungicides on soybeans typically show a positive yield response 75 percent of the time.
Pioneer agronomy research scientists conducted trials from 2004 to 2008 to evaluate the effects of foliar fungicide and fungicide/insecticide applications on soybean yield. Despite considerable variation in growing conditions across years and locations, the trials demonstrated a consistent positive yield response to treatments that included strobilurin fungicides (Headline® and Quadris®). These fungicides, when used alone, showed an increase of 3.3 bushels per acre. When the fungicide was combined with an insecticide treatment, the increase was 4.8 bushels per acre.
“If conditions for foliar diseases are present, foliar fungicides will help increase yields,” says Jim Trybom, Pioneer agronomy research scientist. “Cool and wet conditions in July can create an environment well-suited for foliar diseases in soybeans. If mid-season weather proves to be cool and wet, foliar fungicides may be a good option to protect yield.”
Historically, foliar fungicides for soybeans were used more in the South, but in the last few years, they’ve become more popular in areas of the Corn Belt. This is due to the improved chemistry of foliar fungicides and the increased interest in managing soybeans for higher yields.
“The older chemistry of foliar fungicides for soybeans only included contact fungicides,” Trybom says. “Now, the chemistry has improved, and there are systemic fungicides available.”
Contact fungicides remain on the surface of the plant, so if it rains soon after applying, it can be washed off. Systemic fungicides are absorbed by the leaves and move within the treated plant.
“Systemic fungicides allow growers to properly manage soybeans now more than ever before,” Trybom notes. “Soybeans that have been sprayed retain their leaves for a longer period of time, allowing them to fill longer.” This allows the beans to increase in size and weight, and smaller beans to fill.
Trybom offers several tips for using foliar fungicides:
• Rate. One application of foliar fungicide during the R3 to R4 stages is best.
• Response. It’s important to keep in mind that foliar fungicides on soybeans are more likely to create a positive yield response where foliar diseases are present.
• Timing. Keep cool, wet environmental conditions in mind when deciding whether or not to apply.
• Scouting. Scouting is key in deciding whether or not to use foliar fungicides. Make sure you know which diseases are present or have been present in the field.
• Label. Be sure to read the label of the foliar fungicide for safety precautions and application rates.