VARIATION IN ADULT-POPULATIONS OF THE POTATO LEAFHOPPER (HOMOPTERA, CICADELLIDAE) AND FEEDING INJURY AMONG CLONES OF RED MAPLE

Leaf flush phenology of red maple, Acer rubrum L., changes in the numb er of potato leafhopper adults, Empoasca fabae (Harris), and feeding i njury were recorded for 2 yr for 5 different maple clones. Migratory a dults started arriving between late April and early May. More insects were collected from clone 56026 than from the other 4 clones during th is time. Populations peaked during 31 May-14 June. During that peak, m ore insects were collected from clones 60068, 56026, and 59904 than fr om clones 55410 and 57775. Leafhopper numbers declined thereafter. Lea f flushing (i.e., leaf growth initiation, expansion, and development) differed among clones during April. Clone 55410 was the Ist clone to s how signs of leaf flushing. The order of leaf flushing from early to l ate was 55410 with more leaves than 57775, both followed by 59904, whi ch in turn had more leaves than 60068 or 56026. Leaf flushing of clone 56026 occurred late in the spring. Clone 56026 suffered the most feed ing injury during the growing seasons and clone 57775 showed the least feeding injury. During spring, the cumulative number of leafhoppers c ollected on traps was negatively correlated with the amount of leaf fl ushing and positively correlated with the amount of foliage injury. Th at is, trees with more unexpanded and young leaves had more leafhopper s and, thus, showed more feeding injury. Late in the season, the amoun t of feeding injury was positively correlated with the cumulative numb er of insects caught on traps. Early in the season, amount of feeding injury was, in part, influenced by the degree of leaf flushing. Howeve r, other tree factors appear to influence degree of feeding later in t he season.