Expert offers tips for managing winter wheat

The El Niño (mild) winter weather allowed most soft red and soft white wheat fields to overwinter successfully.  Hopefully the crop will be harvested before La Niña (hot and dry) weather comes.  About 60% of the potential yield for wheat was determined when the drill left the field last fall.

Now it’s time to maximize the other forty percent, while minimizing any environmental effects of pesticides or nutrients leaving the field.  First of all is to split apply spring nitrogen.  Once soil conditions dry out, some nitrogen should be applied now, especially for fields that were planted late or onto coarse textured soils.  However, small plants do not require large doses of fertilizer now.  A later application of nitrogen, such as just prior to Feekes’ growth stage 6, which is the first joint, is one good time to apply additional nitrogen.

MSU recommends that farmers base their nitrogen rates on the yield potential.  The ten year average wheat yield for Monroe County is 74.5 bushels per acre.  The average yield for the past five years was 76 bushels and the average wheat yield for 2015 was 70.4 bushels per acre.  The formula for calculating the amount of nitrogen for wheat is; lbs of N per acre = 1.33 times the potential yield, then subtract 13.  For a 76 bushel yield goal this would be (76 x 1.33) – 13 or 88 pounds of combined fall and spring N.

There has been one report of purple wheat leaves, which probably indicates a phosphorus nutrient deficiency.  The soil temperature on March 30 was only 39.4 degrees F at the MAWN site at the Delmer Cilley farm.  A current soil test should be able to confirm this symptom and cause.

Powdery mildew is the most common leaf disease of wheat.  It also tends to be the earliest to appear in the spring, though can spread to the flag leaf if weather conditions remain favorable.  This disease is more prevalent with cool temperatures (59 to 72ºF) and wet or very humid conditions.  The North Central Committee on Management of Small Grain Diseases (NCERA-184) has developed a Fungicide Efficacy Table last revised a year ago.  This table lists 8 wheat diseases and 13 fungicides from 3 different classes and their efficiency rating, as well as notes about harvest restrictions.

Septoria leaf spot is another leaf disease that is usually prevalent early in the season, prefers cool temperatures (50 to 68ºF) and is favored by wet and windy conditions.  Leaf rust can survive Michigan winters but spores also blow in on winds from southern states.  Leaf wetness and mild temperatures in the 60 to 80ºF range will promote the development of this disease.

The priority is always to protect the flag leaf by applying a fungicide from the time of flag leaf emergence and until early flowering.  This timing can target both leaf diseases and Fusarium head scab.

Now is also a time to broadcast seed red clover into wheat unless there will be a need to use a broadleaf herbicide this spring or unless clover residue may be harvested in the wheat straw, if this is a problem to the end user.

Finally, the Michigan Wheat Program will pay for wheat diagnostic services through the MSU Plant Diagnostic Laboratory.  The form and sampling instructions are at; www.miwheat.org website.