NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
June 1, 2000
Many North Dakota producers have been reporting leaf burn and yellowing on their small grain crops, and some are wondering whether specific varieties are more susceptible to herbicide injury than others. A plant scientist at North Dakota State University says it is unlikely that any of this type of injury is variety related.
"A general request for variety and planting-date feedback when this type of injury has been observed produced multiple responses. In other words, there was no consistency in variety," says Michael Peel, extension agronomist at NDSU.
Most of the wheat with leaf burn and yellowing was planted the last week in April, Peel says. The hot temperatures that ranged from 85 F to about 90 F in early May occurred just as most of this grain was emerging from the soil, and consequently, the wheat sustained some heat canker.
"We typically think of heat canker on small grains as banding," Peel explains. "Since the first leaves were just emerging from the soil, only the tips were burnt."
Then, during the second and third weeks of May, nighttime temperatures fell below freezing in some locations. While none of the small grain was in danger of injury to the growing point, damage to leaf tips did occur, Peel says.
Overall temperatures have not been favorable for rapid plant growth during the early part of the growing season, and in cases where producers didn't use a starter fertilizer, crops now may be deficient in nitrogen (N). Typically older leaves will be yellow while emerging leaves will be greener, Peel says. Tillering may also be less than expected. In areas of ample or excess moisture, root growth may not have reached N supplies. If producers suspect that their small grain crops are suffering from N deficiencies, they should have their soil tested. For additional information consult this NDSU Extension Service publication: "North Dakota Fertilizer Recommendation Tables and Equations Based on Soil Test Levels and Yield Goals" SF-882 (http://www.ext.nodak.edu/extpubs/plantsci/soilfert/sf882w.htm).
In addition, sulfur deficiencies occasionally occur in North Dakota, Peel says. One symptom of sulfur deficiencies, a yellowing similar to N deficiency, often occurs in patches. Deficiencies are usually associated with soils low in organic matter. Only sources of immediately available sulfate sulfur, such as ammonium sulfate, will produce a response when sulfur is low or limiting.
"Slow plant growth and darkening of older plant tissue are associated with cool temperatures," Peel explains. "In corn it is not atypical to see a purpling color of older tissue on young plants during cool conditions. The same type of symptoms are possible on small grains."
When new leaves on wheat plants are showing inter-veinal yellowing, it may be an indicator of iron deficiency, Peel says. Jay Goos, an NDSU soil scientist, reported iron deficiency this spring on wheat in soils with a long history of producing deficiency symptoms in soybeans.
Finally, it is possible that some of the injury producers are seeing this year has been caused by herbicides. If so, skips and misses in the field should help producers determine whether they're experiencing a herbicide-injury problem, Peel says.
Source: Michael D. Peel (701) 231-8037
Editor: Dean Hulse (701) 231-6136