Early decisions critical for wheat

North Texas wheat farmers who intend to produce mostly for grain should look at an October 15 planting date as a good target to get seed in the ground.

Planting earlier, says Travis Miller, Texas A&M Extension agronomist, increases the time the crop is vulnerable to disease, weather and insect problems. Miller discussed basic wheat management recently at a regional seminar in Denton.

“Use cooler temperatures to improve stands and reduce pest problems,” Miller says. “We have to remember that wheat is a cool-season crop with a maximum growth rate at 70 degrees. Growth rate slows at either higher or lower temperatures. Temperatures above 85 degrees can weaken stands significantly.”

Miller says later planting reduces exposure to diseases, greenbug and other pest infestations. “Farmers who grow wheat primarily for grazing have to start earlier and should use favorable weather to seed wheat.”

Miller also recommends wheat producers to pay closer attention to seeding rate. “Know how many seed you're planting,” he says. “The number of seed per pound varies widely, from 11,000 to 19,000 per pound. And with unknown germination from bin-run seed, farmers may not have a good feeling for potential stand. Also, we don't have a good vigor test for wheat seed.”

Miller recommends a plant population of 20 to 25 plants per square foot. “The best way to plant for that stand is to count out 500 seed and weight them,” he says. Knowing how many seed is in a pound could save on planting rate and seed costs, he says.

He says seed per pound varies among varieties and also growing conditions of the seed crop. “Some varieties have larger seed than others and drought, disease pressure and other factors may have affected seed size. Test weight is a good indicator of seed potential. High test weight usually indicates better seedling vigor.”

Miller says a final stand could range from 650,000 to 1.09 million plants per acre.

“Wheat will compensate for stand variations, however. The plant produces tillers that may make up for lower plant populations, but growers still need an even stand. Also, farmers planting forage wheat need a quick, uniform stand.”

Miller says farmers planting wheat with 15,000 seed per pound and an 80 percent emergence rate could sow from 54 to 90 pounds of seed per acre. “That's a big difference and we see no real yield advantage with high seeding rates unless we have adverse conditions during the winter. Extreme cold that could hinder tiller development would favor a higher initial seeding rate.”

Planting depth also affects early wheat growth. Miller recommends farmers plant shallow in a firm seedbed to get a quick, uniform stand. “It's best to prepare the land and then wait for a rain to firm the soil before planting,” he says. “A loose seedbed is the cause of most stand problems.”

Miller recommends farmers control volunteer wheat early, at least two weeks before planting.

“Wheat farmers have a number of pre-plant management choices to make,” Miller says. “They should soil test, determine planting date, prepare the seedbed, decide on seeding rate and depth, determine early fertility program, control weeds, and develop a grazing management program. Farmers who do not make the necessary decisions choose by default.”

Fertility may begin before planting, Miller says, but a single application may not be adequate to take the crop to maturity. Fertilizer placement also plays a crucial role but may vary depending on planting date.

“Phosphorus plays a key role in both grazing and grain wheat,” he says. “The colder the weather gets at planning time, the better response the wheat makes to phosphorus placed closer to the seed. Late in the season, in-furrow placement of phosphorus is more important. Early planting may favor deeper incorporation.”

Miller says applying 80 pounds of nitrogen pre-plant may be as good as anything a grower can do. “But, 40 pounds applied 60 to 90 days after planting will do just as well as 80 pounds applied pre-plant,” he says, “Wheat needs the nitrogen available when it starts its early spring growth spurt.”

He says rate, timing, rainfall and other weather events, plant disease pressure, and field crop history all play a role in wheat's response to nitrogen.

“We recommend adding a little more in wheat following a grain sorghum crop,” Miller says.

He says topdressing wheat provides several advantages, including: taking care of in-season nitrogen losses and the heavy spring nitrogen requirement. Disad-vantages include the added expense of making an extra application. “It costs more to make two applications than it does one.”

Miller advises wheat growers to be aware of certain disease and insect pests. Yellow Barley Dwarf Virus, for instance, can cause serious damage to wheat stands.

“We look for dish-shaped areas in the field,” he says. “Stunting is a symptom.”

Aphids carry the virus and management practices may include controlling the insects with pesticides applied in-season or as seed treatment (Gaucho or Adage).

Destroying volunteer wheat, cleaning fence lines of weeds such as Johnsongrass, planting late, selecting varieties with tolerance and planting no-till help control the virus.

“For some reason, the aphids prefer clean-plowed fields,” Miller says.

He says mono-cropping wheat encourages foot rot. He recommends seed treatments, deep planting, straw disposal and rotation as key management practices.

Rotation “with anything other than wheat,” will help prevent Hessian fly infestations,” Miller says. A Gaucho or Adage seed treatment also may help control the destructive insect pests. “Also look for varieties with resistance and plant later.”

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