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Prepare for 2016 Crop Stressors
Waterhemp to soybean farmers is akin to that obnoxious guest who arrives early at a party and won’t leave as he downs your drinks and gobbles your food. Rather than beer and brats, though, this pigweed family member guzzles soybean yield potential while leaving up to 250,000 seeds per plant for future infestations.
Waterhemp showed up again in 2015. “Driving across the Midwest during August, I rarely saw a clean field,” says Dawn Refsell, field market development specialist with Valent.
Unfortunately, nitrogen (N) deficiencies in corn and white mold and sudden death syndrome (SDS) in soybeans also joined the party. Here are some ways to savage these stressors in 2016.
Preemergence herbicides are a great way to get your soybeans off to a good start.
“Not all pre’s are created equal,” says Refsell. “Some pre’s will only work three weeks, while others work six to eight weeks. The longer the residual, the better – especially with herbicide-resistant weeds. You don’t want them to emerge.”
Eventually, preemergence protection ceases. That’s why timely postemergence applications must be made. Aim to hit weeds when they are small.
“I always tell farmers when they want to apply herbicide on 3-inch weeds to aim to do it when weeds are 1-inch tall, because they tend to be behind on weed height,” says Ryan Lins, a Syngenta research and development scientist based in southeastern Minnesota. This aids control since smaller weeds are more susceptible to herbicide.
Ever think that more intense rains are occurring these days? They are. Peter Scharf, University of Missouri (MU) Extension soil specialist, says 80,000 central U.S. acres, on average, received 16 inches of April-to-June rainfall from 1900 to 1980. That’s now grown to around 200,000 acres annually.
That’s also why you’re seeing more N deficiencies. Provided you can get in the field, in-season N applications are a great way to get N to the plant while it needs it. When all years are tallied in MU trials from 2007 to 2014, sensor-based sidedressing treatments beat preplant treatments by 245 bushels per acre with 164 pounds per acre less N.
If your corn is N deficient due to rainfall-inducted losses, though, first dig up some roots. “You have to make sure there is a root system to take in the nutrients,” says Andrew Ferrel, an Indiana-based commercial agronomist for Mycogen Seeds. “If the roots are damaged, a nitrogen application won’t do you any good. Seemingly alive plants can have no roots.”
In reality, N isn’t your limiting factor in this factor – lack of roots is.
The good news about white mold and sudden death syndrome is they don’t show up every year. The bad news is they both showed up this year in many fields.
Heavy morning dews encourage the advent of white mold but not SDS. Meanwhile, rampant August rainfall doesn’t spawn white mold, but it does promote SDS. This year, both events occurred in many fields.
“What the two diseases have in common is they both affect high-yielding fields,” says Daren Mueller, Iowa State University Extension plant pathologist.
Unfortunately, tolerant varieties to both fungal diseases aren’t in the cards for 2016. Both exist, but tolerance isn’t at the level of other soybean diseases.
In-season fungicides are an option for managing white mold, although application into the lower part of the canopy is challenging. Cultural practices include rotating to a nonhost crop like small grains.
Fungicides don’t work on SDS, even though it’s a fungal disease. Crop rotation to a nonhost crop like small grains is an option, as are seed treatments. This year, Bayer CropScience had its SDS seed treatment Ilevo on about 1 million U.S. soybean acres.
“Ilevo and Poncho/Votivo (Bayer’s products for halting seedling diseases and soybean cyst nematode) work in tandem with good genetics,” says Jennifer Riggs, a Bayer product development manager.