PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
“STRASSERIA” DISORDER OF PINUS RADIATA
Back to Physiological Needle Blight of radiata pine
See also needle diseases of radiata pine
From Forest Health News No. 123, October 2002
Episodic defoliation of Pinus radiata has occurred over a
number of years in Northland, East Cape, Westland and the
central North Island, the most recent major outbreaks being
noted in 1998 and 2000 (FHNews 78:2, 79:2, 102: 2).
Symptoms appear during late winter and spring when foliage
on affected trees becomes red-brown and then turns khaki. The
needles droop but remain firmly attached to branches after
death and may still be present on the tree in late November or
December. Distribution within a stand is usually localised and
in some situations symptoms are present on nearly every tree.
In contrast, Cyclaneusma needle cast differs in that needles
turn firstly yellow and then brown. The needles tend not to
droop but detach very readily, most being cast by late October.
Distribution of Cyclaneusma needle cast is usually scattered
within a stand.
Defoliation in a stand of radiata pine. Incidence is higher in
gullies and adjoining slopes.
Individual trees with severe “Strasseria” defoliation.
Several fungi are commonly isolated from the discoloured
foliage, with Strasseria geniculata often predominating. At
present it is not known whether endophytic fungi play a role in
needle death or merely take advantage of senescent or dead
material as opportunists. The disease has been referred to as
“Strasseria” for convenience, even though no causal
association has been proved or is implied.
In mid-September 2002, “Strasseria” defoliation was reported
from Northland and parts of Coromandel and the Bay of
Plenty. An aerial survey revealed that gullies were
predominantly affected at altitudes above 300 m asl, and the
problem was rarely seen in trees younger than 15 years. For
many trees, over 90% of the crown was affected.
Forest Research is undertaking a research programme, funded
by the Foundation for Research, Science and Technology
(FRST) and the Forest Health Research Collaborative, that
aims to determine the cause of the disease. Plots that are
assessed monthly to monitor disease progress have been
established in Northland and East Cape forests, and glasshouse
trials are underway to determine the effect of prolonged
wetness on needles in the absence and presence of endophytic
fungi. Climatic and environmental factors will be examined to
determine if any relationships with disease severity exist.
I would very much appreciate reports of severe defoliation of
the type described above, with details of disease incidence and
severity, location, topography, crop age, and silvicultural
treatment, in order to build up my database of records.
Margaret Dick (Forest Research) would be grateful for samples
from affected trees from as many locations throughout the
country as possible to carry out fungal isolation tests.
(Lindsay Bulman, Forest Research)
