Louisiana wheat disease management
Realize fungicides are effective against fungal diseases, but NOT effective against bacteria (black chaff) or viral diseases. Application timing and sprayer set up are just as important as the fungicide choice. Ideally, fungicides should be applied before disease onset or when disease incidence is very low. The residual activity of the fungicide may be lost too soon if applied too early. Apply too late, and disease severity may be too high to arrest disease development.
Sprayers should be configured to optimize coverage. Poor coverage of a good fungicide could result in poor disease control. Coverage is af-fected by gallons per acre, pressure, nozzle size, nozzle type, and nozzle spacing. Aerial fungicide applications should deliver fungicides in 4 to 5 gallons of total solution per acre and ground applications should be configured to deliver 10 to 20 gallons per acre.
Nozzles should be selected that deliver small droplets (200 to 300 microns). Nozzles configured to reduce drift potential will usually result in poor coverage. Boom height and nozzle spacing should be adjusted to the manufacturer’s specifications. A boom height too high will in-crease the potential for drift and a boom height too low will not provide adequate overlap for the nozzles. Pressure should be adequate to force fungicide down in the canopy.
On a final note, remember that an effective disease management program will only be successful when all of the components are working together. Efforts must be made to correctly identify the diseases. Choose high-yielding, disease-resistant varieties, and make timely applica-tions of an efficacious fungicide when necessary. For more information concerning disease management in wheat, contact your local LSU AgCenter county agent/specialist.