Kirramyces leaf diseases

General information

Kirramyces leaf diseases are a group of fungal leaf pathogens that infect mature and immature foliage in some eucalypts. They can cause severe defoliation in young trees and may become a significant problem in some hardwood plantations.

Four species of Teratosphaeria have been identified, some of which were known previously as Kirramyces species. They differ with respect to hosts, disease symptoms and known distribution.

Species name
  • Teratosphaeria epicoccoides (previously Kirramyces epicoccoides)
  • Teratosphaeria viscidus (previously Kirramyces viscidus)
  • Teratosphaeria psuedoeucalypti
  • Teratosphaeria corymbiae
Symptoms
  • Teratosphaeria epicoccoides: Initially, small, purple, angular leaf spots are most obvious on the upper leaf surface. These expand and coalesce, eventually covering the entire leaf surface. Lesions on the lower surface turn yellow to yellow-brown, forming angular blotches delimited by leaf veins. Brown to black spores may cover the underside of the leaf, giving a ´charcoal´ appearance.
  • Teratosphaeria viscidus: Circular or irregular necrotic spots appear on both leaf surfaces, and with red borders on the upper surface. Infection can cause severe distortion in young leaves. Conidia (spore masses) appear as crusty black masses. Infection begins in the lower canopy and spreads to the top, in some cases resulting in more than 90% defoliation.
  • Teratosphaeria psuedoeucalypti: Necrotic leaf spots (2-15 mm diameter) appear on both leaf surfaces. They are single or joined, light to medium brown with red-purple margins. Crusty black masses are formed by conidia accumulating on these lesions.
  • Teratosphaeria corymbiae: Leaf spots are yellow-brown to tan and occur on both leaf surfaces. It is more common on trees older than two years, and on fully expanded foliage.
Distribution
  • Teratosphaeria epicoccoides: Widespread throughout the tropics and subtropics.
  • Teratosphaeria viscidus: So far, only identified from Mareeba in North Queensland; possibly more widespread in tropical Australia.
  • Teratosphaeria psuedoeucalypti: Current distribution unknown, but may prefer subtropical and tropical climates.
  • Teratosphaeria corymbiae: Widespread in subtropical areas of Queensland and New South Wales.
Hosts
  • Teratosphaeria epicoccoides: Eucalyptus grandis, Eucalyptus grandis hybrids, Eucalyptus pellita.
  • Teratosphaeria viscidus: Eucalyptus grandis (damage was limited to lower foliage in the Copperload provenance planted where the disease was first detected), Eucalyptus grandis x E. camaldulensis.
  • Teratosphaeria psuedoeucalypti: Eucalyptus grandis hybrids. The full host range is currently unknown, but observations suggest that Corymbia species are not susceptible.
  • Teratosphaeria corymbiae: Corymbia species.
Damage
  • Teratosphaeria epicoccoides: Commonly affects older leaves in the lower canopy, but occurs throughout the crown under certain conditions. Infection in older leaves causes premature senescence and defoliation spreads upwards from the lower canopy. It is seasonal and more common in warmer and wetter months. Severe infection has resulted in complete defoliation.
  • Teratosphaeria viscidus: The most severe impact has been seen in E. grandis x E. camaldulensis hybrids originating from South America. Infection in new shoots and young foliage resulted in high levels of defoliation (75%).
  • Teratosphaeria psuedoeucalypti: Severe defoliation (>75%) has been recorded in Central and South East Queensland. Repeat infections have made some areas no longer viable for commercial plantations of susceptible species. Impact has been greatest in Eucalyptus grandis hybrids.
  • Teratosphaeria corymbiae: Rarely severe enough to cause defoliation.
Management
  • Teratosphaeria epicoccoides: No specific chemicals have been registered for this pathogen.
  • Teratosphaeria viscidus: There is not a management strategy for this disease, as E. grandis hybrids are not planted commercially in Far North Queensland. Relatively low disease levels recorded on Australian E. grandis (Copperload) suggest that host populations may have some resistance. Tree germplasm developed overseas in the absence of Australian pests and diseases are potentially more susceptible.
  • Teratosphaeria psuedoeucalypti: Avoid planting E. grandis hybrids, particularly germplasm developed overseas.
  • Teratosphaeria corymbiae: None required.

References

For current information on pesticides registered for use in forestry:

Last updated 19 October 2012