Influence of First-Generation White Apple Leafhopper (Homoptera: Cicadellidae) and Leaf-to-Fruit Ratio on Apple Fruit Size and Quality

Abstract

Girdled limbs of ‘Campbell Redchief Delicious’ apple ( Malus domestica Bork-hallser) trees were treated with a factorial combination of four first-generation white apple leafhopper, Typhlocyba pamaria McAtee, populations and three leaf-to-fruit ratios. Fruit size, fruit soluble solids concentration, and fruit surface red color were related positively to leaf- to-fruit ratio, whereas none of the indices of fruit size or quality was consistently influenced by leafhoppers. These data indicate that action threshold levels for first-generation leafhoppers should be increased to three or more leafhoppers per leaf.