Late fall rains cut into wheat acreage and forced late planting in the upper Southeast. Record early winter freezes have also put wheat that was planted in jeopardy, leaving many growers to ponder whether to pull the plug or continue adding inputs to insure a reasonable crop this spring.
North Carolina State University Small Grain Specialist Randy Weisz says growers in the upper Southeast face some critical management choices in the next few weeks. Most of these choices, he contends, will be based on visual observations and reactions by growers, but there are some things that will help make these management decisions less risky.
If the grower determined that by Feb. 1, there were enough tillers already in the field to make a good crop, they will almost certainly be nitrogen stressed. Getting 20-30 pounds per acre of nitrogen on those stressed tillers is critical. This nitrogen can be applied as soon as there are several days with daytime temperatures of at least 50o F.
On the other hand, if the stand is thin (less than 50 tillers per square foot), then 50 to 70 pounds of nitrogen needs to be applied as early in February as possible.
A thin wheat stand not only needs nitrogen, but also provides an ideal environment for weeds, making good weed control a must in a salvage situation.
“We don’t usually worry too much about burning wheat a little bit with herbicides, but this year in thin stands every spot of green tissue is critical. Controlling weeds without damaging wheat will be a big challenge for growers this year,” Weisz says.
A standard and highly effective wheat weed treatment is Harmony Extra plus nitrogen. It is a good option, but can burn wheat. If growers are going this route, this year it will be a good idea to leave adjuvants out of a tank-mix with nitrogen to try and reduce burning, he adds.
Bluegrass is a constant foe of upper Southeast wheat growers. Osprey is the only option for bluegrass control, but it must not be applied within 14 days of a nitrogen treatment, is slow to act, and only effective on clumps no larger than a quarter. Growers must evaluate which need is more immediate, the bluegrass control or the wheat’s requirement for nitrogen. In many cases this year it may come down to a question of if the bluegrass is too far advanced and/or the wheat too thin to justify carrying these fields to harvest, says Weisz.
In thin wheat fields that need nitrogen, Italian ryegrass control is another tricky issue. Hoelon cannot be tank-mixed with nitrogen, and Osprey cannot be applied within 14 days of nitrogen. Growers who need to manage ryegrass and also get nitrogen out quickly might consider PowerMax. PowerMax can be tank-mixed with up to 30 pounds of nitrogen. If more nitrogen is needed it can be applied 7 days later.
Weisz says there are reports that some growers planted wheat in January during a lull in freezing weather. This too, he says, is a high risk proposition for North Carolina and Virginia growers.
Henry Walker, who grows grain crops near Winston-Salem, N.C., says he and his son seriously considered planting wheat in January. “We had the seed and we really needed to plant wheat for our crop rotation, but we just couldn’t make it work economically,” he notes.
In eastern North Carolina, veteran Crop Consultant Bruce Niederhauser says the wheat crop is a mess. “We have seen some miracle fields in which wheat we thought was dead from the days of sub-freezing temperatures came back to life. How well these fields perform remains to be seen,” he adds.
Niederhauser cautions growers who had wheat survive the wet and freezing weather keep a close watch on their crop. This was such an unusual weather pattern and growers who don’t grow wheat every year, or haven’t grown it over a long period of years, may benefit from having someone with a lot of experience help them keep track of the crop this year, he adds.
Wheat growers will likely face an increased threat from cereal leaf beetles this spring. Cereal leaf beetles prefer thin wheat fields and spring tillers. “If you have a field planted on time, with good management practices that has predominantly fall tillers and an adjacent field with predominantly spring tillers, cereal leaf beetles will choose the spring tillers,” Weisz says. Unfortunately, the 2010 crop, because of the wet weather, will have predominantly spring tillers.
Research in North Carolina and Virginia has shown it is not advisable to tank-mix an insecticide with top-dress nitrogen for cereal leaf beetle control. In 10 trials, the insecticide applied at top-dress time either was not needed or failed to control cereal leaf beetle. This year, Weisz recommends checking wheat fields in mid-April and spraying if there are more than 25 eggs-plus-larvae on 100 tillers.
Whether fungicides pay off in wheat is a long-running question. With marginal yield potential in this year’s crop, spending extra money on fungicides will be a real tough one for growers.
Weisz has results from over 280 wheat fungicide tests conducted in North Carolina and Virginia over the past years to try to answer the question of fungicide use on wheat. Results run the gamut from increasing yields by up to 20 bushels per acre to decreasing yields by 10 bushels per acre.
Over the entire 280-plus tests, the average yield increase was 5 bushels per acres.
Weisz says that when fields were rated as having “little to no” foliar disease in them a fungicide application was not economical. On the other hand if growers followed a few simple steps the data showed that fungicides could be profitably applied.
The first question is does the wheat field have enough yield potential to warrant the extra cost of application? If so, the second question is simply, “is there any disease present”?
Weisz recommends a quick visual inspection. If there is “little to no disease” skip the fungicide. If there is more than “a little” disease, the third question is “what disease do I have”?
If powdery mildew is the problem, propiconazole is the cheapest and most effective fungicide. If stagonospora nodorum blotch (what used to be called septoria) is present, than the strobilurin fungicides (and especially Headline) are most effective.
For leaf rust, any of the strobilurin fungicides should be used. For a mixture of powdery mildew, and either of these other diseases, a combination fungicide like Quilt, Twinline, or Stratego might be best.
These three steps greatly increase the likelihood of getting a profitable response to a fungicide, says Weisz.
Fusarium head blight, commonly called wheat head scab, is more common in a late-planted crop. This is because the later wheat is planted, the later it will flower and the later it flowers the warmer the temperatures will be. Scab infects wheat during flowering and infection is enhanced by high humidity, rain, and warm temperatures.
Weisz says that growers should monitor the weather around flowering (late April and early May) and be on guard for scab infections. If scab is a disease problem, strobilurin-containing fungicides can increase vomitoxin levels in the grain, and are not the best choice for control.
Growers who are worried about head scab should consult a special publication available from cooperative Extension or on-line at http://www.smallgrains.ncsu.edu/SmartGrains/No26SCAB.pdf for assistance, Weisz says.
Making the right decisions on pest management and wheat fertility is always important, but on this year’s crop those decisions are essential just to determine whether to keep the crop growing or pull the plug and cut losses to a minimum.
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