Purdue News
Purdue News
January 10, 1997
Because some of the crop prematurely broke dormancy during the unseasonably warm weather of late December and early January, the soft red winter wheat, planted in fall for harvest this spring, needs a good snow cover to insulate it from the cold, according to OSU plant pathologist Pat Lipps and Purdue wheat specialist Ellsworth Christmas.
"We need a good couple inches of snow and moderately cold temperatures to maintain a snow cover," Lipps said. He said it's too early to predict yield losses, but that the recent warm and cold fluctuations took their toll.
Christmas agreed.
He said the warm spell that sent Indiana temperatures into the mid-60s between Dec. 28 and Jan. 6 caused some wheat varieties to break dormancy and begin to grow. At the end of the warm period, temperatures dropped 40 degrees in less than 48 hours to lows in the low 20s to high teens.
The quick temperature change was key.
"Temperature drops of this magnitude in a short period can result in significant leaf tissue burn and death," Christmas said. "The extent of this type of injury will not be evident for about a week.
"The Jan. 9 snowfall has given most of the state the needed two inches for adequate protection from the very cold temperatures in the forecast for this weekend (1/11-12)," Christmas said. "The far southeastern portion of Indiana, along the Ohio River, has received less than one inch of snow and could still be vulnerable to cold injury."
Christmas said the wheat needs at least a week of temperatures around the freezing mark for plants to return to a dormancy level at which they are safe from extreme cold temperatures approaching zero.
"In most cases, the plants will not reach the same level of dormancy that they had attained prior to the period of regrowth," Christmas said. "But it is our opinion that the Indiana wheat crop has not suffered significant damage to date."
Warm and extreme cold temperature fluctuations with no snow cover would further damage the crop, according to Lipps, who added that the next two months are critical to wheat's survival.
The late-planted crop in Ohio could be vulnerable to winter injury because some plants did not grow enough before going into dormancy in late November. Wheat ideally needs two to three tillers to survive winter, but it grew only one to two tillers because of the late planting and cold weather in November.
"Wheat has to have sufficient growth in the fall to produce enough carbohydrates to make it through the winter," Lipps said. "The lower the carbohydrates, the greater the chances for winter injury."
Ohio farmers planted their wheat late because they were busy harvesting a delayed soybean crop. On average, Ohio farmers planted winter wheat 2 to 2-1/2 weeks late. Although some wheat started to regrow during the past two weeks, it was not enough to produce more tillers.
In Indiana, however, most early-season factors influencing the winter wheat crop were positive. Christmas said soil moisture and weather conditions during fall 1996 planting were "quite good."
"Most of the crop was seeded in a timely fashion with a slightly higher percentage seeded a little later than normal," he said. "Establishment was good, with good stands and adequate but not excessive growth prior to entering dormancy."
Some wheat varieties fared poorly during the recent weather fluctuation because they break dormancy very easily. Farmers should select varieties that are winter-hardy, Lipps said.
"The key is for farmers to get information on how winter-hardy their varieties are," Lipps said.
ACS code/970110 Christmas.wheat
ahr/Christmas.wheat/9701f12
Sources: Ellsworth Christmas, (765) 494-6373; e-mail, echristmas@dept.agry.purdue.edu
Pat Lipps, (216) 263-3843; e-mail, lipps.1@osu.edu
Writer: Amy H. Raley, (765) 494-6682; e-mail, ahr@aes.purdue.edu
