Disjointed: Did winter wheat get bit by frost?

WOOSTER, Ohio – The recent bout of cold weather may have slowed the development of Ohio’s wheat crop, but frost damage is anticipated to be less severe in Ohio than in more southern wheat-growing states.
Timing. Pierce Paul, an Ohio State University plant pathologist with the Ohio Agricultural Research and Development Center, said the majority of the wheat wasn’t jointed yet when the cold temperatures hit earlier this month. Prior to jointing, the crop is less sensitive to subfreezing temperatures.
“That was the saving grace for Ohio. Cold temperatures are most damaging to the crop when the wheat is at more advanced stages of development,” said Paul, who also holds an Ohio State University Extension appointment.
“Some injury, seen as burning and discoloration of leaf tips, has occurred, and is more prevalent in fields with early-planted wheat. In addition, fields found in low-lying areas or planted with varieties that are more sensitive to cold temperatures tend to look worse.”
Physiology. According to the Ohio Agricultural Statistics Service, only 14 percent of Ohio’s wheat crop is jointed. As the crop develops in the spring, it loses its cold-temperature hardiness, becoming more sensitive to freezing temperatures in the spring.
During boot and heading growth stages, cold temperatures may cause sterility, resulting in little or no kernel development.
“Before the wheat is jointed, the growing point is much closer to the ground and is protected from cold temperature injuries. But once the wheat starts to joint, two hours or more of exposure to temperatures of 24 degrees Fahrenheit and colder can be damaging,” said Paul.
Growers can assess any potential damage by walking their fields and examining the growing point on 10 to 15 randomly selected tillers. Remove the leaves, split the stem lengthwise and examine the growing point, which is located above the uppermost node.
What to look for. A healthy growing point will be white to yellowish-green, while a damaged growing point will look water-soaked and off-white or brownish in color.
Yield potential is reduced if tiller numbers fall below 25 per square foot after green-up. Fifteen tillers per square foot is considered minimum for an economic crop.
“Prior to the cold spell, the crop looked much better than we thought it would have, given the planting and winter conditions we had,” said Paul.
“Once we get away from the cold temperatures and it starts greening up again, the wheat should be just fine. Remember, we are dealing with a cold season crop that can tolerate and bounce back from the conditions we have had.”