Diseases of Small Grains

Diseases are often a major yield constraint in the production of wheat, oats, and barley in New York State.

Many disease-induced losses have been accepted by growers because of either a lack of acceptable control practices or a lack of disease detection. Disease management has been accomplished to some extent through the use of sound cultural practices, seed-treatment fungicides, and varieties resistant (or at least less susceptible) to certain diseases. With renewed interest in intensive management, the severity and importance of diseases have increased, and greater emphasis has been placed on the use of newly available foliar fungicides.

Overall, the most important diseases are fungal foliar diseases. These include Stagonospora nodorum blotch, Septoria tritici blotch, tan spot, powdery mildew, and leaf rust on wheat; crown rust, Septoria blight, and leaf blotch on oats; and powdery mildew, net blotch, scald, and leaf rust on barley. Foliar diseases, if severe during the first few weeks after flowering, can drastically reduce grain yields.

Soilborne fungal diseases affecting the roots, crowns, and lower stems occur on cereals in New York but are seldom severe. This is probably because small grains seldom follow each other in rotational sequence in New York and the same cereal species is almost never continuously cropped. Diseases such as take-all, Fusarium root and crown rot, eyespot and other foot rot diseases can reduce cereal yields under certain conditions in New York.

Yellow dwarf, caused by aphid-transmitted viruses collectively called barley yellow dwarf and cereal yellow dwarf viruses, affects all cereals in New York and can be a serious problem. Wheat spindle streak mosaic, caused by a virus that is transmitted by a soilborne fungus, occurs widely on wheat and causes significant losses in growing seasons having prolonged cool periods in April and May. Wheat cultivars with resistance should be grown in New York. Wheat soilborne mosaic, caused by a virus that is also transmitted by a soilborne protozoan, occurs only in certain areas of the southern Finger Lakes Region and causes significant yield loss in susceptible varieties. Wheat cultivars are available with resistance to both of these soilborne viruses.

Smut and bunt diseases attack cereals by replacing the tissues of the developing kernels with masses of fungal spores. Although still potentially devastating, smut diseases have largely been controlled through planting of certified seed and the use of systemic seed treatments.

Fusarium head blight or scab can seriously reduce yields and result in mycotoxin-contaminated grain and low-vigor seed in all cereal crops if moist conditions exist at the time of flowering. A new extension web site called Scab Smart (www.ag.ndsu.edu/scabsmart) provides up-to-date information on the integrated management of Fusarium head blight.

Contact your local Cornell Cooperative Extension office for recent fact sheets and other information available to aid in the identification and control of small grain diseases.

Small grain diseases are most effectively managed by an integrated approach that makes use of genetic, cultural, and chemical tactics of disease control. The following tactics are most often incorporated into cereal disease management.

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