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Fight Scab Using Aerial Application

Wet fields may require fungicide to be applied by aircraft.

By Vern Hofman, Professor Emeritus

NDSU Agriculture and Biosystems Engineering

There could be major Fusarium head blight (scab) problems for wheat and barley producers because of the wet weather across the region. If wet weather coincides with the heading and flowering stage of the crop, serious yield and quality losses could occur. Inoculum of the Fusarium disease is available in nearly every wheat and barley field in the northern Plains or can come from a nearby field, so the potential risk is nearly always present.

A management strategy to control scab is to use a fungicide. The wet fields may require fungicide to be applied by aircraft. Airplanes can cover large acreages in a short time and eliminate the wheel tracks in the field.

A considerable amount of research has been completed during the last five years to determine the best method of fungicide application by air. A new publication has been released by the NDSU Extension Service that provides recommendations on setting up an aircraft to apply fungicide on wheat and barley. It is titled ""Aerial Application of Fungicide for the Suppression of Fusarium Head Blight in Small Grains"" (AE-1327). A copy of the publication can be found on the NDSU Web site at http://www.ag.ndsu.edu/pubs/plantsci/pests/ae1327.htm or is available from your local Extension Service office.

The best aerial application is to produce drops of 300 to 350 microns in size applied at 5 gallons per acre. Drops smaller or larger are not recommended. Small drops of about 200 microns in size will collect on the awns extremely well, but fungicide on the awns does little good at controlling scab. The spray drops need to move beyond the awns to the glumes. Larger drops of 400 microns or more provide poor coverage and control.

Booms on aircraft should be mounted as low as possible below the wing and the nozzles should not cover more than about 65 percent to 70 percent of the wing span. This helps discharge spray into the air with the least amount of turbulence. Turbulent air causes droplet breakup and spray drift.

Smaller aircraft should operate at a minimum height of 8 to 10 feet above the crop. Larger, faster aircraft should operate at 10 to 12 feet above the crop. Flying too low will provide a poor spray pattern and poor control.

Entire coverage of the head is desirable for good scab control. However, typical spray operations are capable of covering only one side of the head. The NDSU studies have found that covering one side of the head well, and with limited systemic movement of the fungicide, good control of the disease is possible.

NDSU Agriculture Communication

Source:Vern Hofman, (701) 231 vernon.hofman@ndsu.edu
Editor:Rich Mattern, (701) 231-6136, richard.mattern@ndsu.edu
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