SPATIAL AND TEMPORAL ANALYSIS OF TOBACCO ETCH VIRUS DISTRIBUTION AND ITS RELATIONSHIP TO APHID (HOMOPTERA, APHIDIDAE) VECTORS IN FLUE-CUREDTOBACCO

The contribution of colonizing and transient aphids to the primary and secondary spread of tobacco etch virus (TEV) in flue-cured tobacco wa s evaluated in North Carolina in 1985 and 1986. Transient aphids were apparently responsible for both primary and secondary spread of the vi rus. Aphid colonization had no effect on the distribution of TEV infec tions in tobacco, and insecticidal control of aphids had no effect on disease progress. Primary spread of TEV was responsible for the majori ty of infections early in the season (up to 8 wk after transplantation ). Primary and secondary spread were both clustered about previously i nfected plants in the field early in the season. Toward the end of the season, new infections became randomly distributed with respect to pr evious infections in the field.