Forest health condition in New South Wales, Australia, 1996–2005. II. Fungal damage recorded in eucalypt plantations during forest health surveys and their management

Abstract

Forests New South Wales (NSW) manages over 26 000 ha of young eucalypt (Eucalyptus and Corymbia) plantations, established since 1994, in NSW, Australia. Forest health surveillance of these plantations was initiated in late 1995: results for damage from fungal diseases, including foliar, stem and root fungi, are summarised for surveys from 1996 to 2005. The main pathogen in Corymbia spp. plantations was Quambalaria shoot blight, caused by Quambalaria pitereka, which caused shoot death, affecting growth and form. Kirramyces (=Phaeophleospora) epicoccoides caused significant defoliation (>75% severity) of Eucalyptus grandis and E. grandis×Eucalyptus camaldulensis clones in several locations from 2000 onwards, often resulting in infection by stem fungi leading to top-death and tree mortality. Kirramyces eucalypti caused significant defoliation (>95% severity) of Eucalyptus nitens over several years in two plantations, which also resulted in infection by stem fungi and top-death and tree mortality of many trees. Other leaf fungi (e.g. Mycosphaerella cryptica, Mycosphaerella marksii, Aulographina eucalypti and Pilidiella eucalyptorum) were common on several host species, but rarely reached a level of serious concern. Holocryphia eucalypti was associated with elongated perennial cankers, top-death and tree mortality of Eucalyptus dunnii in plantations severely defoliated by insects and fungi or that had experienced severe windstorms. Botryosphaeria spp. were associated with twig cankers and shoot dieback of Eucalyptus pilularis on stressed sites, but also with root-bole damage and scattered mortality of several hosts during drought. Caliciopsis sp. pleomorpha was associated with localised branch and stem cankers, mostly of stressed trees, on a range of hosts from 2003 onwards, and severe cankers leading to tree mortality of E. nitens. Phytophthora cinnamomi was associated with mortality of several hosts in years following episodes of high rainfall. Mortality from Armillaria luteobubalina was rare. Management options for these diseases are discussed, and include: (1) risk-site mapping to assist in targeting management options; (2) increasing tree resistance via tree breeding; and (3) increasing tree tolerance to damage, and recovery after damage, via silvicultural regimes such as fertiliser application and improved site-species matching.