Above-normal temperatures this winter have caused Kentucky’s wheat crop, and weeds, to grow ahead of schedule. Early-planted fields may have wheat at growth stages Feekes 4 (erect) or Feekes 5 (several inches tall). Wheat at these stages may look like it’s ready for a nitrogen application, but that may do more harm than good say specialists with the University of Kentucky College of Agriculture.
“If the weather remains warmer than normal, these fields may be at risk of severe cold injury if the growing point moves above the ground while there are still chances for temperatures below 24 degrees Fahrenheit when the plant has jointed (Feekes 6),” said Lloyd Murdock, UK extension soils specialist.
To minimize its chance of cold weather injury, wheat should not joint until well into March. An additional nitrogen application in February may encourage them to joint sooner. Murdock added that since much of the crop has tillered well, early nitrogen isn’t needed.
“In fact, it would be good if the plants were slightly deficient in nitrogen, because it would slow their growth,” he said.
For wheat that is well tillered and at Feekes 3 or early Feekes 4, producers can apply a low rate of nitrogen of about 30 to 40 pounds per acre to fields this month. Producers who have fields with plants at Feekes 3 or Feekes 4 and not well tillered should apply nitrogen at a rate of 40 to 60 pounds per acre this month.
Although much of the wheat is growing quicker than normal, so are weeds. Jim Martin, UK extension weeds scientist, said wheat producers might want to review their weed management plans.
“The situations that have the greatest risk from weed competition are no-till fields that were not treated with a burndown application before planting or post-emergence herbicide treatment after crop emergence in the fall,” Martin said. “Specifically check for wild garlic emergence to be sure that most plants have emerged. Common chickweed and Italian ryegrass are examples of cool-season annuals that are competitive and should be controlled early.”
Growers should make sure they get good coverage when spraying herbicides to ensure the best possible weed control. They also need to ensure herbicides are only sprayed when conditions are favorable. Crop injury can occur when producers spray herbicides before, during or after heavy rainfall, prolonged cold temperatures or widely fluctuating daytime and nighttime temperatures.
Martin said the wheat’s growth stage will affect what herbicides producers can use on the crop. Also, when applying an herbicide to control ryegrass, producers should be aware that spraying certain herbicides around the same time as top-dressing nitrogen can injure wheat.
For more information, view the Feb. 9 issue of Wheat Science News on the UK Wheat Science Group homepage, Newsletter.