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| There are at least 25 species of aphids that can vector barley yellow dwarf virus. Many of them either do not occur in Kentucky, or are not important in virus movement. We commonly see three species on small grains here, thebird-cherry oat aphid, the corn leaf aphid and the English grain aphid. The greenbug occasionally is present but does not seem to play an important role in BYDV movement. Though not yet proven, we suspect the the rice root aphid a very important virus vector is present. This aphid is not often seen because it feeds primarily on the roots. While it probably is not important in virus spread within the field, it may serve to introduce the virus into the field. The bird cherry-oat aphid probably is the most important mover of BYDV because it is common in the fall and is active during most of the winter. In contrast, the corn leaf aphid is present for a relatively short time in the fall. The English grain aphid generally appears too late in the spring to play a large role in virus movement. |