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Kirramyces leaf diseases

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 are known, some of these were previously referred to as Kirramyces species. They have different hosts, disease symptoms and known distribution.

Scientific name

Teratosphaeria epicoccoides (previously Kirramyces epicoccoides), T. viscidus (previously K. viscidus), T. psuedoeucalypti, T. corymbiae

Description

Teratosphaeria epicoccoides

  • Initially, small purple angular leaf spots are obvious on upper leaf surfaces. 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.

T. viscidus

  • Circular or irregular necrotic (disease) spots appear on both leaf surfaces, with red borders on the upper surface.
  • Severe shape 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.

T. psuedoeucalypti

  • Necrotic (diseased) leaf spots (2–15mm diameter) appear on both leaf surfaces.
  • Spots are single or joined, light to medium brown with red-purple margins.
  • Crusty black masses are formed by conidia (spore masses) accumulating on lesions.

T. corymbiae

  • Leaf spots are yellow-brown to tan and occur on both leaf surfaces.
  • Usually affects fully expanded foliage on trees older than 2 years.

Distribution

Teratosphaeria epicoccoides

  • Widespread throughout the tropics and subtropics.

T. viscidus

  • Only identified from Mareeba in North Queensland
  • Possibly more widespread in tropical Australia.

T. psuedoeucalypti

  • Current distribution unknown but may prefer subtropical and tropical climates.

T. corymbiae

  • Widespread in subtropical areas of Queensland and New South Wales.

Hosts

Teratosphaeria epicoccoides

  • Eucalyptus grandis
  • E. grandis hybrids
  • E. pellita.

T. viscidus

  • Eucalyptus grandis (damage was limited to lower foliage in the Copperload provenance)
  • E. grandis x E. camaldulensis.

T. psuedoeucalypti

  • Eucalyptus grandis hybrids
  • Full host range unknown but observations suggest that Corymbia species are not susceptible.

T. corymbiae

  • Corymbia species.

Damage

Teratosphaeria epicoccoides

  • Affects older leaves in the lower canopy but sometimes throughout the crown.
  • Infects older leaves causing premature senescence (deterioration with age) and leaf-loss spreads upwards from the lower canopy.
  • Common in warmer and wetter months, and seasonal.
  • Severe infection can result in complete defoliation.

T. viscidus

  • Severe impact has been seen in Eucalyptus grandis x E. camaldulensis hybrids originating from South America where infection in new shoots and young foliage resulted in 75% defoliation.

T. psuedoeucalypti

  • Severe defoliation (>75%) has occurred in central and south-eastern Queensland.
  • Repeat infections have made some areas no longer viable for commercial plantations of susceptible species.
  • Greatest impact on Eucalyptus grandis hybrids.

T. corymbiae

  • Rarely severe enough to cause defoliation.

Monitoring and action

Teratosphaeria epicoccoides

  • No specific chemicals have been registered for this pathogen.

T. viscidus

  • No management required, as Eucalyptus grandis hybrids are not planted commercially in Far North Queensland.
  • Relatively low disease in Australian E. grandis (Copperload) suggest some resistance.
  • Tree germplasm developed overseas in the absence of Australian pests and diseases is potentially more susceptible.

T. psuedoeucalypti

  • Avoid planting E. grandis hybrids, particularly germplasm developed overseas.

T. corymbiae

  • None required.

Resources and research

Contact

General enquiries 13 25 23