Purdue News

February 6, 1998

Warm winter may mean weakened wheat

WEST LAFAYETTE, Ind. -- Warm weather has weakened some winter wheat in the Midwest, according to Purdue University Cooperative Extension Service wheat specialist Ellsworth Christmas.

He said most of Indiana's crop broke dormancy in early January and, after going dormant again, some of the crop may have broken dormancy a second time during the warmth of recent days.

"It's our opinion that the Indiana wheat crop has not suffered any injury. However, each time the wheat breaks dormancy and grows for a short period before re-entering dormancy, root reserves are lowered and the vigor of the plant declines," he said.

If that decline has happened, Christmas said, the crop will be more vulnerable to Rhizoctonia, a potentially fatal disease farmers can't prevent or treat. These warm spells also increase the danger that the soil will heave, particularly on wet, poorly drained or heavy soils, he said.

Christmas said growers can check plants to find out if they've broken dormancy by following these steps:

Carefully wash the roots of a wheat plant and look for new root growth coming from the crown area. These roots will be snow white and may be only a quarter-inch or a half-inch long if the plant has just broken dormancy.
Look closely at the top two leaves of the plant. There should be a line at the point where the leaf had been covered by the leaf sheath. If the plant has broken dormancy, there will be shiny new leaf tissue below the line, next to tissue that is duller.

Regardless of the wheat's dormancy status, Christmas advised against applying nitrogen right away. "We would suggest that nitrogen application be delayed until we get closer to that time when wheat will break dormancy and continue to grow actively," Christmas said. "Early application with the warm periods that we have experienced could cause excessive growth and make the plant more vulnerable to freeze injury."

When growers do apply nitrogen, Christmas advised using dry materials or using streamer bars for liquids.

"Every effort should be made to keep as much of the nitrogen fertilizer off the wheat leaves as possible. Nitrogen fertilizer applied to a plant with lowered vigor and dead leaf tissue could cause a significant Rhizoctonia problem," he said.

CONTACT: Christmas, (765) 494-6373; e-mail, echristmas@dept.agry.purdue.edu

Compiled by Chris Sigurdson, (765) 494-8415; E-mail, sig@ecn.purdue.edu
Purdue News Service: (765) 494-2096; e-mail, purduenews@purdue.edu

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