SDSU Extension Plant Pathology - Barley yellow dwarf virus of winter wheat

Plant Pathology, South Dakota State University

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Fig 1. Yellow tips of wheat leaf infected early in the season by barley yellow dwarf virus (BYDV).

Fig 2. Aphids feeding on wheat stems can spread BYDV. Because aphid activity decreases in the fall, plant winter wheat after September 15.

Fig 3. Severe BYDV often looks very bad, but spring infection, such as is pictured here, rarely leads to significant yield losses. Losses can be greatest in fall infected winter wheat.

Barley yellow dwarf virus of winter wheat

Symptoms
Leaves may have yellowish or reddish leaf tips if infection occurs early in the growing season (Fig. 1), or they may remain green and symptomless.

Spread of BYDV
Early seeded winter wheat is most at risk due to the presence of aphids that transmit the virus. Any of several grain aphid species present in South Dakota may acquire the virus by feeding on an infected plant (Figure 2.). They will carry the virus in their bodies until they die. The virus is not transmitted during short feeding probes. Rather, the aphid has to feed for several hours to allow the virus to infect the plant. Vector pressure from aphids that spread yellow dwarf and mites that spread wheat streak mosaic, another virus disease, are major reasons for planting winter wheat after September 15.

Yield Loss
The crop outlook from infected fields is variable. How extensive the infection is across the field and the weather for the coming season are the main concerns. Potential for loss in winter wheat infected in the fall is much greater than in spring grains infected at a later stage of development. Yield losses can approach 60-70% in plants infected in the seedling stage. If infection occurs nearer heading, such as we might encounter with spring grains, less than 10% yield loss may occur. A small number of infected plants will not cause large losses, whether the infection occurs in the fall or spring. Infected plants will produce underdeveloped root systems. If the year is cool with plentiful moisture, losses will be low. If the year is hot and dry, losses will be greater. Insecticides to control the aphid vectors in the spring are ineffective in managing yellow dwarf.

Web sites with further information and photos:
Barley Yellow Dwarf Virus Manitoba Agriculture and Food Barley Yellow Dwarf Virus Disease of Small Grains - download and print a comprehensive bulletin from the University of Illinois

Contact Info
Martin Draper Plant Science Dept, South Dakota State University