Teratosphaeria leaf diseases

Teratosphaeria epicoccoides

• Initially, small purple angular or irregular leaf spots are obvious on upper leaf surfaces. These expand and coalesce, eventually covering the entire leaf surface.
• Brown spots with red-purple margins, 7–25mm in diameter, have also been observed.
• 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. viscida

• Circular or irregular necrotic (disease) spots appear on both leaf surfaces.
• Spots are 3–20mm in diameter, single or joined, pale to medium brown with red-brown borders on the upper surface and pale brown on the lower leaf surface.
• There is 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. pseudoeucalypti

• Necrotic (diseased) leaf spots, 2–15mm in diameter, appear on both leaf surfaces.
• Spots are circular to irregular, single or joined.
• They are initially pale green, turning chlorotic before becoming necrotic, light to medium brown with red-purple margins.
• Crusty black masses are formed by conidia (spore masses) accumulating on lesions.

T. corymbiae

• Leaf spots, 1–10mm diameter, occur on both leaf surfaces.
• They are single or joined and yellow-brown to tan with a thin green-brown to red-purple margin.
• It usually affects fully expanded foliage on trees older than 2 years.

T. cryptica

• Leaf spots, variable in size and shape, single or joined, are light brown to red-brown, becoming dark grey with age, frequently with a prominent purple, raised margin.
• It commonly infects young expanding leaves, often causing the leaf to become crinkled and contorted.
• Small black fruiting bodies are often seen within leaf spots, aggregating on leaf veins, and prominently on the underside of leaves.
• It causes different symptoms on different hosts, but almost always results in characteristic leaf crinkling.

Teratosphaeria epicoccoides

• Widespread throughout the tropics and subtropics

T. viscida

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

T. pseudoeucalypti

• Subtropical and tropical climates

T. corymbiae

• Widespread in subtropical areas of Queensland and New South Wales

T. cryptica

• Throughout the east coast of Australia, also in Tasmania and Western Australia

Teratosphaeria epicoccoides

• Rose gum and hybrids (Eucalyptus grandis)
• Large-fruited red mahogany (E. pellita)
• Forest red gum (E. tereticornis)

There are more than 200 host species in total.

T. viscida

• Rose gum (E. grandis)
• Rose gum x river red gum hybrid (E. grandis x E. camaldulensis)

T. pseudoeucalypti

• Rose gum and hybrids (E. grandis)
• Forest red gum (E. tereticornis)

The full host range is unknown but observations suggest that Corymbia species are not susceptible.

T. corymbiae

Hosts are Corymbia species.

• Spotted gum (C. variegata)
• Spotted gum (C. maculata)
• Large-leaved spotted gum (C. henryi)

T. cryptica

• Yellow stringybark (E. acmenoides)
• River red gum (E. camaldulensis)
• Gympie messmate (E. cloeziana)
• Dunn's white gum (E. dunnii)
• Southern blue gum (E. globulus)
• Rose gum and hybrids (E. grandis)
• Tallowwood (E. microcorys)
• Shining gum (E. nitens)
• Large-fruited red mahogany (E. pellita)
• Blackbutt (E. pilularis)
• Sydney blue gum (E. saligna)
• Forest red gum (E. tereticornis)

Teratosphaeria epicoccoides

• Symptoms are variable and depend on host species and stage of development of infection.
• This is generally considered a minor pathogen that causes disease on older leaves or on stressed trees without having a major impact on growth. However, high levels of T. epicoccoides can cause significant damage or death on offsite or poorly managed plantations.
• It affects older leaves in the lower canopy but sometimes spreads throughout the crown.
• It infects older leaves, causing premature senescence (deterioration with age). Leaf loss spreads upwards from the lower canopy.
• It is common in warmer and wetter months, and seasonal.
• Severe infection can result in complete defoliation.

T. viscida

• 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. pseudoeucalypti

• 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.
• The greatest impact is on Eucalyptus grandis hybrids.

T. corymbiae

• This is rarely severe enough to cause defoliation.

T. cryptica

• This causes defoliation, mostly in the lower crown.
• It can affect young twigs and stems in addition to leaves, resulting in characteristic cankers.
• Such cankers eventually lead to stem damage, dieback, crown thinning, tree malformation and, in severe cases, death of entire trees.
• The preferred host species E. globulus and E. nitens are not commonly grown in Queensland, so this is a less important pathogen here.

Teratosphaeria epicoccoides

• No specific chemicals have been registered for this pathogen.

T. viscida

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

T. pseudoeucalypti

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

T. corymbiae

• None action is required.

T. cryptica

• None action is required. Preferred host trees are not grown in Queensland commercially.

• Andjic, V, Carnegie, AJ, Pegg, GS, Hardy, GESJ, Maxwell, A, Crous, PW, Pérez, C, Wingfield, MJ, Burgess, TI, 2019, 23 years of research on Teratosphaeria leaf blight of Eucalyptus, Forest Ecology and Management, 443:19–27, viewed 2023.
• Carnegie, A, Lawson, SA, Smith, T, Pegg, GS, Stone, C,M cDonald, J, 2008, Healthy hardwoods: a field guide to pests, diseases and nutritional disorders in subtropical hardwoods, Forest and Wood Products Australia, Victoria.
• Crous, PW, Wingfield, MJ, Cheewangkoon, R, Carnegie, AJ, Burgess, TI, Summerell, BA, Edwards, J, Taylor, PWJ, Groenewald, JZ 2019, Foliar pathogens of eucalypts, Studies in Mycology, 94(1):125–298, viewed July 2023.
• Hunter, GC, Crous, PW, Carnegie, AJ, Burgess, TI, Wingfield, MJ, 2011, Mycosphaerella and Teratosphaeria diseases of eucalyptus; easily confused and with serious consequences, Fungal diversity, 50(1):145–166, viewed July 2023.
• Pests and diseases image library (PaDIL)