Farm Forestry New Zealand
PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
From the pathology bench
From Forest Health News 70, December 1997 - January 1998.
Two specimens of the seldom seen Pachysacca pusilla crossed the pathology bench in one week during November. The first of these samples was collected by Brent Rogan (MoF) on Eucalyptus rossii, from Victoria Esplanade, Palmerston North. Symptoms are raised (almost gall-like) black leaf spots up to 5 mm diameter. A second specimen was collected a week later from a forest in the Bay of Plenty, by John Pascoe (MoF) on E. regnans. Lesions were smaller in diameter and not as prolific. We have seen only one other specimen of P. pusilla since 1988. All specimens have been recorded from the southern part of the North Island and the hosts include E. botryoides, E.fastigata, E. delegatensis, E. regnans and E. viminalis . Eucalyptus rossii is a new host record for New Zealand. Pachysacca pusilla , one of three species of Pachysacca recorded from eucalypts (and the only species recorded in New Zealand), was first described from E. regnans in Victoria, Australia. It is a very interesting fungus from a pathological and morphological point of view. The fungal fruiting bodies are often invaded by other fungi, as occurred on the E. rossii specimen. The symptoms vary between hosts, i.e. on E. regnans lesions are described as being up to 1.5 mm diameter whereas on E. rossii lesions were much larger. This fungus has not caused significant defoliation in any New Zealand locations.
(Kiryn Dobbie, FRI)
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