Differential Impact of Insect Herbivores and Fungal Pathogens on the Eucalyptus Subgenera Symphyomyrtus and Monocalyptus and Genus Corymbia

Abstract

Comparisons of tree height, diameter, survival and levels of canopy damage from insect pests and fungal pathogens in young plantations of mixed eucalypt species were undertaken at three sites in north-eastern New South Wales (NSW). Results support the hypothesis that species of the informal subgenus Monocalyptus suffered less damage from insects and fungi than Symphyomyrtus. We demonstrated that under an intensive regime of insecticide and fungicide application Symphyomyrtus species tended to attain higher growth rates than the Monocalyptus. However, among the untreated controls the fastest growing trees were species of Monocalyptus. Multivariate biplot analyses consistently illustrated an affinity of Monocalyptus closer to Corymbia than Symphyomyrtus in terms of levels of damage from insects and fungi and relative growth rates.