Farmers in the South who are encouraged enough by improved prices and yield potential to plant wheat in 2011 should not ignore production basics, especially during the most important times of development for the crop, says Erick Larson, Mississippi State University Extension agronomist.
Wheat production in Mississippi, as in other parts of the South, has ebbed and flowed in recent years, but an increase is expected in fall plantings.
“Over the past several years, we’ve had as many as 500,000 acres and as few as 100,000 acres,” said Larson at the Central and South Alabama Wheat Expo, held in Montgomery, Ala.
“One thing I can tell you from a production standpoint is that we’ve been producing some very good wheat yields in recent years. Of course, we’ve had a good environment for it. We’ve had a lot of wheat producing well over 80 bushels per acre, and some growers recorded yields as high as 110 and 113 bushels per acre. There is a high level of productivity potential with wheat.”
It’s important, says Larson, that growers understand the physiology and development of wheat so they can realize as much yield as possible.
Wheat is different from other crops, he says, primarily in that it is a winter crop.
“The three main growth stages for wheat are tillering, stem elongation or vegetative development after it starts to grow upright, and then the heading stages. Most summer crops go through the same development stages or progression, but with wheat, we have a winter dormancy, and that causes some issues,” he says.
Wheat doesn’t respond to our early planting systems as do summer crops like soybeans and particularly corn, he adds.
“Early planting can produce some problems in wheat production. In the South, we really don’t have as much true winter dormancy as the more traditional wheat-growing regions such as Kansas and even Kentucky. They have a very definitive winter season where the wheat is truly dormant and there is no growth during the winter-time.
“In the South, it doesn’t get cold enough sometimes for the wheat to go truly dormant during the entire course of the winter. If our wheat gets too lush in the fall, that can be an issue. If we’re late with our planting, the wheat can have a chance to catch up as long as other things like wet, saturated conditions aren’t holding it back too much,” says Larson.
In terms of management and what these different time periods mean, growers usually focus on the springtime in terms of its significance to wheat management, he says. But just as important are the fall and early spring when the wheat is going through the tillering stages.
“As far as wheat’s yield potential, you’ve got the number of heads, which will be determined during fall and up through early spring. Once the wheat starts the stem elongation period, possibly in early March in some areas, the number of heads is already determined.
“So if you have not put out your springtime application of nitrogen fertilizer in time enough to supply nutrition to those plants, you’re basically stuck with the resources and the physiological aspects of that plant for that time period.”
Provide all resources
It’s important that producers make sure they have the resources to develop the optimal number of heads that the wheat crop can produce, says Larson, because that is an extremely important component in terms of overall yield capability.
“So not only is your springtime management important but also your fall and winter management,” he says.
Tillering, explains Larson, is the development of additional stems per every seed that you plant. “With wheat, we plant in terms of developing about 23 to 30 plants per square foot. But a good, high-yielding wheat crop should have somewhere in the neighborhood of up to 75 heads per square foot at harvest-time.
“We don’t plant to a harvestable population with wheat. We rely upon the wheat’s physiology and the resources out in the field to produce the optimal number of heads.
“We need to make sure those resources are out there because tillers contribute about 60 to 80 percent of your total heads which is 60 to 80 percent of your total yield.”
The bottom line, he says, is that the seeding rate is not very critical in wheat production.
“Obviously, you do want to get a stand, but you also want to have the resources there and hold back the competition that would prohibit that wheat crop from developing the optimal number of tillers based upon your field and growing conditions.”
Oftentimes, says Larson, a grower will drive by a field and take it for granted that it’s a good stand of wheat. In reality, you need to take a closer look between the rows.
“You might find there’s a need for fall weed control in your crop. You can have a very healthy stand with various winter annuals in the field, such as buttercup, henbit and annual bluegrass. A lot of things could be competing with wheat and taking up nitrogen and the other nutrients, as well as competing for light.
Will hold back tillers
“Some of these small-stature winter weeds are not on the upper part of our radar screens in terms of competition with wheat because they don’t look very significant. But they will hold back tiller development in the spring.”
Herbicide application can have an influence in wheat yields, as shown in trials conducted in Mississippi, he says.
In his state, says Larson, a lot of the wheat crop is grown in the northwest or Delta region, with flat soils and poor surface drainage. This results in problems with water management and soil saturation.
“That makes it very difficult in terms of nitrogen management for wheat production. Our wet winters can cause de-nitrification and leaching. So we apply nitrogen only in the fall when we’re planting wheat late or have very thin stands, or where we’re planting into a pasture or where we need to break down the residues that are tying up nitrogen in the production system.”
Mississippi growers don’t apply much nitrogen in the fall because they know they’re going to lose it over the winter, says Larson. This makes application timing during the spring very important.
“If we go out too late with that first application of nitrogen, we’re not going to supply the nutrition needed to support as many tillers as that wheat plant has the potential to produce, so we lose wheat potential right off the bat.
“If we do put out nitrogen during that time of the year — which could be during the first couple of weeks of February — the crop won’t enter rapid nitrogen uptake until at least six or seven weeks after that time period. It won’t hit those rapid growth stages until mid to late March. We don’t want all of our nitrogen applied in early February, where it could be subject to tremendous nitrogen losses for five to seven weeks.”
This is why, says Larson, split nitrogen applications are recommended on wheat in Mississippi. “There are years when we have a dry spring, and we probably won’t get responses to split applications in those years.”
Nitrogen, he says, should be delivered according to crop demands, and that means the first application in the spring after dormancy should probably be no more than one-third of the total spring-time nitrogen.
“Then, come back with the remainder of the nitrogen just prior to stem elongation. Some growers who have aerial application capabilities are not making that last application until a little bit later on in the vegetative stages. Then, it just needs to be put out prior to the boot stage.”