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Control Recommendations: Wheat
Cultivars Management Practices Pesticides
Barley yellow dwarf is the most widely distributed and destructive of the virus
diseases that affect wheat. Symptoms of barley yellow are often confused with various
nutritional or non-biological disorders. Leaf discoloration induced by the virus infection
typically ranges from shades of yellow to red and sometimes purple, especially extending
from the leaf tip to the base and from the leaf margin to the mid-rib. Seedling infections
reduce yields most. Plants infected in the fall of the year may not survive the winter or
are severely stunted and discolored when growth resumes in the spring. These diseased
plants often occur in circular patches within the field. These patches are associated with
the feeding and colonization by the aphid vectors in the fall and early spring. Grain
yields from such plants have been shown to be reduced by 30 to 35 percent in experimental
plots in Virginia.
The virus can be transmitted by more than 20 species of aphids, five species of
which are known to occur in Virginia. The virus persists in
small grains (barley, oats, rye and wheat), in corn, and in over 80 species of perennial
and annual grass species. The spread of this virus is entirely dependent on the activity
of the aphid vectors. The environmental conditions that favor barley yellow dwarf
epidemics are cool temperatures (50 degree to 65 degree F) with rainfall that favors wheat
and grass growth as well as aphid reproduction and movement. Infections can occur
throughout the season and are most abundant where high populations of aphids survive the
winter. The leaf discoloration symptoms indicating virus infection develop within about
two weeks of inoculation at temperatures between 65 degree to 70 degree F. When infections
occur at temperatures above 85 degree F, symptoms do not develop.
The best means of control in barley is to select cultivars that are resistant to the virus and not to plant early in the season. Wheat cultivars range from highly susceptible to moderately susceptible. Planting later in the season will reduce the risk from fall infections of barley yellow dwarf, but this may not be enough in some years. A seed treatment insecticide has been shown to be highly effective in preventing fall barley yellow dwarf infections and significantly reducing spring infections as well.
When barley yellow dwarf has been common in a field and culture is directed towards higher yields then a seed treatment insecticide may be economically beneficial.
Control Recommendations: Wheat Cultivars Management Practices Pesticides
| Disease Management Practices | Foliar Diseases | Seed and Seedling Diseases | Root and Crown Diseases | Head Diseases | Virus Diseases |
