OBSERVATIONS OF FIRST OCCURRENCE AND SEVERITY OF POTATO LEAFHOPPER, EMPOASCA-FABAE (HARRIS), (HOMOPTERA, CICADELLIDAE) IN THE NORTH CENTRALAND EASTERN UNITED-STATES

This paper presents available data on the :first occurrence dates and the damage severity of the potato leafhopper in the north central and north eastern United States collected during the past 47 years (1951-1 997). The data were collected from a variety of sources including: pot ato leafhopper literature review; published reports; pest alerts; pest surveys; and delphi surveys. First occurrence and severity data show that the arrival time of potato leafhopper and subsequent damage sever ity varies substantially from year to year. A correlation analysis bet ween date of first occurrence and severity of damage for Michigan, Min nesota, Wisconsin, the north central region and the northeastern regio n indicated no significant relationship between first arrival dates an d damage severity. The lack of a relationship between the time of arri val of the migrant leafhopper and severity indicate that other factors , including frequency and magnitude of arrivals, weather conditions du ring the growing season and crop management contribute to the eventual severity of damage caused to crops by this migratory pest. The analys is of potato leafhopper severity data showed significant differences b etween years. There were no significant differences in severity among states within the north central region, indicating that potato leafhop per severity is a regional phenomenon.