winter wheat stress rainfall leaching

WHEAT LOOKS good across the Upper Southeast as the crop heads into 2014, says North Carolina State Specialist Randy Weisz.

Monitor wheat crop for any signs of stress

• Basically, last year’s nitrogen is gone and so are potash and sulfur in all but the heavy clay soils in the Piedmont region.  

Record rains last spring, summer and fall across much of the Upper Southeast have left soils poorly adapted to producing a wheat crop this winter, says North Carolina State Small Grain Specialist Randy Weisz.

Speaking at the recent North Carolina Crop Consultants meeting, Weisz said that basically last year’s nitrogen is gone and so are potash and sulfur in all but the heavy clay soils in the Piedmont region.

Wheat needs at least 30 pounds of nitrogen per acre pre-plant in the fall, then another 60 pounds or so in late January and another 30-40 pounds in March.

The January-February application of nitrogen is especially critical if tillers are thin.

Even in fields where wheat tillers appear to be thick, it is a good idea this year to scout regularly for signs of nitrogen stress, the North Carolina State specialist said.

“With the amount of rain and cool weather we’ve had before wheat was planted, and even into the winter, this is a good year to keep a close watch on the crop for any signs of stress.

“In many areas of the state, it’s a good bet that all the potash and sulfur are gone. It’s best to correct shortages of these nutrients with fall application, but it will likely be better to fix the problem late, than to not fix it at all,” Weisz said.  “For sure, growers don’t want to wait and see whether  or not they have phosphate and potash deficiencies — not this year,” he added.

Check current wheat futures prices

“This is a good year to act quickly on yellow wheat. Getting soil and tissue samples out and back quickly will be critical in getting proper nutrients to wheat. On some of these nutrient-related problems, if you wait too long, they cannot be turned around, though most can be overcome by quick reaction to stress, the North Carolin specialist says.

Warm days and freezing nights, combined with plenty of moisture has created a situation in which many growers are seeing symptoms in their wheat that looks like winter kill. There is plenty of evidence that this unusual late fall-early winter weather pattern has created stress that has left wheat around the state with what looks like winter kills.

Good news

The good news, Weisz says, is that so far no one has reported digging up wheat plants and finding the growing points brown and black and clearly water-logged and dead.

Record rainfall throughout the 2013 growing season pushed harvest of virtually every crop back two weeks or more. Combine late harvest with the amount of nutrients taken from the soil and the problem of lack of nutrients for the 2014 wheat crop is magnified.

Corn, for example, under more normal growing conditions removes about three-quarters pound of nitrogen per bushel, 1.2 pounds per bushel of wheat and 3.6 pounds per bushel for soybeans. Combined with the heavier loss rate of nutrients under heavy rainfall conditions, lack of nutrients is not only likely in many parts of the Carolinas and Virginia, it is almost certain to occur.

Per bushel losses of phosphate, potash and sulfur are much smaller, but may be just as important when calculating how much of these nutrients were lost to heavy rainfalls on the 2013 crop.

Potassium removed from the soil on soybeans is about .75 pound per bushel. On corn, the loss is about a third pound and on wheat about a tenth of a pound per bushel.

Sulfur is critical to the growth of wheat and though smaller amounts are lost when the crop is harvested, these losses still represent a significant reduction in relation to the amount applied.

On soybeans, sulfur lost to the plant is about .18 pound and roughly half that amount for corn and wheat.

“I never thought I’d be talking about ways to make wheat profitable, but based on the latest prices, this looks like a real good year to take a careful look at input costs,” Weisz says. 

“Over the past few years growers have had good prices and generally good crops, and some have tried some things that sometimes work and sometimes don’t on wheat. With prices where they are now (early December), it may be time to look at each input and determine how valuable it is in relation to how much it may increase yield, quality and value of the crop,” he adds.

Beetle likely to be a problem

Weisz says cereal beetle is likely to be a problem this year and there are two strategies for managing this pest.

One is cheap: adding a recommended insecticide to your January-February fertilizer application. Basically, you have the cost of the insecticide. The advantage is that it’s cheap, the disadvantage is that the insecticide may be gone by the time cereal beetles become a problem.

“A bigger problem with this strategy may be that you don’t know you have the problem, until defoliation shows up and there is a good likelihood that there will be a yield loss.

“My suggestion is don’t put the top-dress and the insecticide on in February. Delay the top-dress as long as possible to get best cereal leaf beetle control, but get it out before jointing starts in the wheat,” Weisz says.

The third week or so of April is a better time to apply an insecticide only if needed. This strategy can save a lot of money, because in many cases cereal leaf beetle won’t appear in some fields.

The downside is that there is extra cost in scouting and in some cases there may some damage to the crop from running a sprayer through it in April.

In the long-run, the cost of these two strategies is about the same. Likewise, the risk factors are about the same, but regardless of which course of action a grower chooses, they should scout that third week in April to determine whether they missed insects with the early spray and to be sure they need to spray with a dedicated spray in April.

“Despite the late harvest of most crops, it appears the wheat crop in the Carolinas and Virginia was planted in a timely manner. So, in North Carolina, wheat seems to be progressing well, despite the extra rainfall in much of the state,” Weisz says.

As usual, expectations are high, despite the low prices for wheat, and how the year goes will likely be decided in part by how well growers were able to cope with the loss of nutrients from the 2013 cropping season.

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