Resistance of Eucalyptus species to Glycaspis brimblecombei (Homoptera: Psyllidae) in the San Francisco Bay area.
The resistance of 21 cultivated Eucalyptus species to G. brimblecombei was assessed from 1998 to 2000 in the San Francisco Bay area of Northern California, USA. Based on the presence of eggs and nymphs, and the occurrence and severity of tree defoliation, the majority of the species were rated as resistant or tolerant including E. cinerea, E. cladocalyx, E. ficifolia, E. globulus, E. grandis, E. paniculata, E. platypus, E. polyanthemos, E. pulverulenta, E. robusta, E. saligna, E. sideroxylon and E. viminalis. Four species (E. diversicolor, E. leucoxylon, E. macrandra and E. nicholii) were rated as tolerant to moderately susceptible. Only three species (E. camaldulensis, E. rudis and E. tereticornis) exhibited heavy defoliation and were rated as moderately to highly susceptible. Leaf epicuticular wax appears to be involved with resistance because all glaucous species or glaucous leaf types within a species were resistant.