SUSCEPTIBILITY OF SELECTED SHADE AND FLOWERING TREES TO GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE)

Twenty-one shade and flowering trees were planted in a cultivated opening surrounded on three sides by gypsy moth-infested forest stands. Three Malus cultivars, Salix babylonica, Acer platanoides 'Royal Red' and 'Crimson Sentry,' and Prunus cerasifera 'Thundercloud' were the most heavily defoliated (30-70%) each year. Acer rubrum 'Northwood' and 'October Glory', Tilia cordata 'Greenspire,' and Tilia americana suffered low to moderate defoliation (4-20%). Acer platanoides 'Emerald Queen,' Acer saccharinum, Fraxinus pennsylvanica 'Marshall Seedless,' Platanus x acerifolia 'Bloodgood,' Pyrus calleryana 'Redspire,' Acer platanoides 'Deborah,' Prunus serrulata 'Kwanzan,' Gleditsia triacanthos var. imermis 'Sunburst,' and Magnolia x soulangiana lost < 4.0% of their foliage because of gypsy moth feeding injury. A wide range of host plant resistance levels among cultivars of A. platanoides and species of Acer and Prunus indicates a need for evaluating cultivars of shade trees susceptible to gypsy moth. In a separate study at the same site, Acer rubrum 'Northwood' planted in the cultivated opening was more heavily defoliated (14.4%) by gypsy moth larvae than similar trees planted in the adjacent forest stand (6.6%).