Selection of Disease Resistant or Disease Tolerant Varieties
Cereal varieties should be selected with resistance or tolerance to diseases important in your area. Keep in mind that even a moderate level of resistance may be adequate to avoid significant losses to certain diseases. It is particularly important to select varieties with resistance to Fusarium head blight, soilborne viruses, leaf rust, and powdery mildew. Resistance to diseases such as rusts and smuts may be specific against certain pathogen races, so make sure that the variety you select is resistant to all fungus races known to occur in your area.
Treating cereal grain seeds with fungicides is sound insurance against a number of diseases that impair stands, reduce yields, and lower grain quality. Certified seed is treated with fungicide(s) by the seed supplier. Certain products are also available for wheat producers to apply as a slurry or seedbox application to nontreated seed. Contact your farm supply dealer for information on specific products. Seed fungicides are essential for control of smut and bunt diseases. Seed fungicides also kill fungi that cause seed decay and seedling blights. Only certain fungicides (mefenoxam and metalaxyl) are strongly active against oomycete pathogens such as Pythium, so seed treatment products often include combinations of fungicides. A few systemic fungicides also have seedling foliar activity that reduces fall rust and mildew infections. Some new seed treatment products include biological ingredients with efficacy against plant parasitic nematodes.
Foliar and head diseases induced by fungi can reduce the yield of small grains in New York State. Experiments with fungicides in non-maximum-yield situations, however, have sometimes shown reduction in disease with little resulting yield benefit. Fungicides, therefore, should be used as one part of a total management system. Factors such as variety selection, planting date, weed and insect control, and fertility should be optimized before fungicide use is considered. Powdery mildew, leaf rust, and fungal leaf and glume spots are among the diseases most frequently encountered. Because disease occurrence varies between fields and between seasons, fungicides are most effectively used in conjunction with a scouting program. One of the major aims of a foliar fungicide program is to keep the flag leaves free from disease because flag leaf function is important for filling the grain. Early-season diseases can also adversely affect yield, however.