Seed treatment, other inputs pay off in winter wheat

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Winter wheat is a low-input crop — if you want low returns — says Brian Beres, an Agriculture Canada research scientist leading a Prairie-wide study on winter wheat agronomy. “Winter wheat is like any other crop,” he says. “It needs decent inputs to perform to its potential.”

Beres’s team is working to develop an integrated crop-management program for winter wheat, evaluating practices to manage fertility, weeds, diseases and insects.

Some management practices are relatively low cost with a big payback.

For example, a fall application of 2,4-D will help a well-established crop outcompete weeds in spring, saving the cost of a further herbicide application.

“As well as cutting costs, that gives you non-chemical weed control, helping you manage herbicide-resistant weeds,” Beres says.

Seed treatment pays for itself, according to Beres. The trials included plots with each component used for seed treatment, but Beres advises using a product that includes both a fungicide and an insecticide.

He says that any time you have a situation that’s less than ideal for the crop — a less-competitive variety, low-vigour seed or less-than-ideal conditions — you have what agronomists call a “weak agronomic system.” In those cases, the benefits of dual-action seed treatment really show up, apparently by giving the plants an edge over the winter.

Fall fungicide

Beres added a mid-October application of foliar fungicide to the study last year because stripe rust was a problem in several areas. It’s not often considered, but it certainly seems worthwhile if the crop has symptoms of stripe rust infection.

“I highly recommend scouting your fields for any signs of stripe rust in fall,” says Beres. “Spray a foliar fungicide in the fall if you find symptoms of the disease. It definitely helps the crop and may eliminate the need for a spring application of fungicide, which is often difficult to do.”

Researchers say that at some sites, crops treated with foliar fungicides in fall look more vigorous, even if there were no signs of disease in fall.

“The fungicide treatment just seems to give you a more robust and vigorous plant,” says Agriculture Canada disease specialist Kelly Turkington. “I suspect seed treatment and foliar fungicides limit development of leaf disease in fall and early spring.”

However, Beres says he doesn’t advise spraying a fungicide in fall if you don’t see symptoms. “At least, not until we have some more data.”

Winter wheat is vulnerable to stripe rust because its main vegetative growth phase is in April and May, when spore production is building in the Pacific Northwest where the pathogen overwinters. Winds from the southwest can then carry the spores. Usually, only southern Alberta has been affected, but in the last couple of years the disease has affected crops farther north and east. The pathogen can also overwinter in southern Alberta, using a “green bridge” to pass from an infected spring cereal to winter wheat.

“The impact of stripe rust depends on when it gets here and the stage of the crop at the time of infection,” says Turkington. “The key time is from flag-leaf emergence to anthesis (flowering), so scout diligently ahead of this stage so you can spray promptly.”

He says that with cereal leaf diseases you can protect yield by spraying as soon as symptoms develop. That’s too late for some other diseases like sclerotinia in canola, where you need to spray before symptoms develop.

Most winter wheat varieties are susceptible to stripe rust. New races of the pathogen have overcome the resistance of AC Radiant, but McClintock, Moats, Peregrine and Sunrise varieties are resistant.

Other findings

  • Nitrogen-uptake research shows AC Radiant uses fertilizer N applied during the growing season more efficiently, but CDC Ptarmigan is more efficient at scavenging for N in the soil. Many farmers are looking at applying UAN (28-0-0, liquid N) to winter wheat in spring, possibly using a Greenseeker to place the N where the crop is well established.

The agronomy study team is working to develop a computer program to enable a Green-seeker-guided sprayer to apply the level of N needed in each area of a Prairie winter wheat crop.

  • Winter wheat does well after canola, peas and other pulses and barley. But, following camelina, which seemed a good option because it’s a short-season oilseed, led to ragged stands as volunteer camelina outcompeted the winter wheat and reduced nutrients and moisture available to the crop. Researchers are now addressing control of weeds that are becoming bigger problems in winter wheat — cleavers, downy brome and Japanese brome. At Lethbridge, treatments include fall- and spring-applied Everest, Simplicity, Payload and the soil-applied herbicide, pyroxasulfone.

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