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Wheat Can Keep Pests Off Balance

This small grain can keep pests off balance and benefit other crops in a rotation.

Wheat hasn’t been able to buy a break in recent months. Its plunging price has caused it to be jettisoned in crop rotations.  

Then again, maybe some of wheat’s benefits are those that it brings to other rotational crops. A 12-year University of Illinois (U of I) study found that adding wheat to a corn-soybean rotation boosted corn yields by about 10 bushels per acre and soybean yields by 3 to 5 bushels per acre, says Emerson Nafziger, a U of I Extension agronomist.

That’s why Todd Hanten, Goodwin, South Dakota, keeps wheat in his crop lineup. “There is a definite yield advantage,” he says. Hanten plants spring wheat on about one fourth of his acres, with the rest split between corn and soybeans.

Typically, spring wheat hasn’t been as profitable as corn and soybeans. “Corn and soybeans got to be more profitable crops,” he says. “Yields jumped so much. That’s why I went to a lot more continuous corn and corn-soybean rotations.”

What happened, though, is that pests crashed these tight rotations. “Waterhemp has emerged as being tough to control, tough to kill,” he says. “I also had lots of problems with lambsquarters, kochia, and wild buckwheat.”

Cultural practices like diversifying crop rotations interrupt weed cycles. Weeds still are an issue in wheat, but Hanten has been able to apply herbicides that give excellent weed control. They also add different sites of action to forestall herbicide resistance in corn and soybeans.

He sprays herbicides early – when wheat is 4 to 6 inches high – in order to control weeds when they are small.

Crop rotation also helps spurn pests in other crops. Hanten has been able to forego corn that resists corn rootworm and even to plant straight Roundup Ready corn in some cases. That’s because wheat helps break up those insect cycles.

Cover crops

Spring wheat also provides a cover crop springboard. Cover crops can fit in a corn-soybean rotation, but penetrating crop canopies during midsummer aerial seedings is challenging. Establishment is easier when cover crops are drilled into wheat stubble.

Hanten plants a five-way cover crop mix (including radishes, cereal rye, and hairy vetch) following mid-summer wheat harvest. The cover crop provides water and nutrient-cycling benefits before Hanten plants corn into the field the next year.  Cover crops like radishes can also help shatter compaction.  

Challenges

Hurdles exist, though. Wheat’s recent price slump has tightened margins. Diseases like fusarium head blight (scab) also can plague wheat. Timely fungicide applications are key to controlling these diseases.

“I have seen big benefits some years,” he says. “I don’t get it every year, but I had a 20-bushel-per-acre yield benefits from a fungicide application one year.” In that case, striped rust struck a susceptible variety."

Weather patterns can also raise havoc. A series of wet springs last decade and extending into this one dashed spring wheat planting plans. Fortunately, drier springs have made it possible to plant spring wheat once again, he says.

Conversely, challenges have been offset by benefits. Wheat stubble provides a place for nutrient-rich cattle manure to be applied. Wheat also provides a way to spread out equipment and labor.

“I plant it early and harvest in the summer, and that alleviates (equipment and labor) pressure in the fall for corn and soybeans,” says Hanten.

Wheat also enables Hanten to strip-till stubble early for next year’s corn, as he applies phosphorus, potassium, sulfur and zinc. He follows up a split-application nitrogen strategy in the next year’s corn.

Besides grain, dairies moving into the I-29 corridor in eastern South Dakota have also created a market for wheat straw bedding.

“For me, wheat has been a good fit,” he says.

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