PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Stigmina thujina on Lawson cypress in New Zealand
STIGMINA THUJINA
Leaf spot caused by Stigmina thujina
From Forest Research bulletin 220, 2001
LAWSONS CYPRESS DEFOLIATION
From Forest Health News 70, December 1997- January 1998
STIGMINA THUJINA - A NEEDLE BLIGHT OF LAWSONS CYPRESS?
From Forest Health News 70, December 1997- January 1998
DEFOLIATION OF LAWSONS CYPRESS
from Forest Health News No. 50, February 1996
Leaf spot caused by Stigmina thujina
From Scion publication Forest Research Bulletin 220
An Introduction to The Diseases of Forest and Amenity Trees in New Zealand
G.S.Ridley and M.A. Dick 2001
Species: Stigmina thujina (Ascomycete anamorph)
Common name: None
Country of origin: Pacific Northwest of North America
Host(s): Chamaecyparis lawsoniana, C. pisifera, C. obtusa, Cupressus sp., Thuja plicata.
Symptoms: Infection commonly occurs on leaves but has been found on small twigs, leading to dieback. Older foliage, nearest the main stem, is affected first and susceptible trees may retain only an outer rim of green (Fig. 33). Dark-brown fruit-bodies occur on necrotic areas of leaves and twigs.
Disease development: Not known.
NZ distribution: Stigmina thujina is found in the central North Island, Canterbury, Nelson, and the West Coast.
Economic impact: In most locations the disease is of little consequence, but severe defoliation of C. lawsoniana in some plantations has led to a policy of replanting with other species (Fig. 34).
Control: None available.
Fig. 33: Foliage of Chamaecyparis lawsoniana infected by Stigmina
thujina
Fig. 34: Compare the Chamaecyparis lawsoniana (right) defoliated by
Stigmina thujina with the unaffected Thuja plicata (left)
History: The earliest New Zealand record of Stigmina thujina, held at the New Zealand Forest Research Institute, is from 1963 when it was identified on C. lawsoniana from Queens Gardens in Nelson. There is one overseas report of serious defoliation of C. lawsoniana in association with S. thujina infection. In 1982 needle blight of planted C. lawsoniana was reported on several islands in Hawaii. Within a group of trees, disease severity ranged from no symptoms to complete defoliation and death. It was concluded that differences in individual tree susceptibility were responsible for the variation in symptoms, as in several groups healthy trees were next to those which were heavily defoliated. The symptoms described in Hawaii are identical to those observed in New Zealand. Chamaecyparis lawsoniana originates from coastal North America, as apparently the fungus does also, but there are no reports of defoliation associated with S. thujina from that part of the world. Although pathogenicity tests have not been carried out on C. lawsoniana, either here or in Hawaii, observations over many years show a consistent association of this fungus with a particular set of symptoms, strongly suggesting a cause and effect relationship.
References: Bradbury 1997; Dick 1997; Funk 1985; Hodges 1982
LAWSONS CYPRESS DEFOLIATION
From Forest Health News 70, December 1997- January 1998
Late in 1993 heavy defoliation of Lawsons cypress was observed at Slab Hut Creek, south of Reefton on the west coast of the South Island. The symptoms extended from the bottom of the tree crowns to mid upper crown level and appeared to affect all but the current years foliage in the upper crown. This gave the trees a scorched and sparse appearance, and since then a number of the trees have died. Although the majority of trees in any one stand are affected there are often individuals which retain full crowns. Inspection in the same area about a year earlier found the trees to be in good health with no observable defoliation.
Since the problem 'first' appeared at Slab Hut Creek similar defoliation has cropped up on both individual trees and in stands of Lawsons cypress from Westport to Hokitika on the West Coast and in a stand near Nelson, the latter suffering defoliation within the past six months. Defoliation varies slightly within affected stands but generally trees uniformly suffer 40-80% defoliation.
To date all the samples sent to FRI have consistently had the fungus Stigmina thujina isolated from the affected foliage.The forest health database has records of Lawsons defoliation associated with Stigmina thujina in the central North Island as far back as the mid 1980s, including samples collected from the grounds of FRI and the Kinleith mill. The fungus has also been isolated from samples collected within the last four years from individual Lawsons cypress trees at Lyttleton, Nelson and Wellington.
(Paul Bradbury, MoF)
STIGMINA THUJINA - A NEEDLE BLIGHT OF LAWSONS CYPRESS?
From Forest Health News 70, December 1997- January 1998
The earliest New Zealand record of Stigmina thujina in the FRI Mycology Herbarium dates back to 1963 when it was identified (as Coryneum thujinum , the then name for the fungus) on Chamaecyparis lawsoniana from Queens Gardens in Nelson. The fungus was first described from Thuja plicata in Oregon in 1924 but was not regarded as a pathogen of any note, and with any published references tending to be taxonomic in content. In 1971 a brief comment following a redisposition of the fungus to the genus Sciniatosporium simply stated "As far as it is known S. thujinum is restricted to Thuja plicata and occurs throughout most of the range of its host in the Pacific Slope region of western North America".
FRI records of S. thujina have accumulated slowly. The second chronological record, also on C. lawsoniana, was collected in Granville Forest in 1974 and the fungus was then not seen in the diagnostic laboratory until 1981. With one exception, on T. plicata, all records are on C. lawsoniana .
One report of serious defoliation of C. lawsoniana in association with S. thujina infection exists in the literature. In 1982 Hodges reported a needle blight of planted Lawsons cypress on several of the islands in the Hawaiian group. Severity of the disease within each group planting ranged from no symptoms to complete defoliation and death. The symptoms described are identical to those observed in New Zealand. Hodges concluded that differences in individual tree susceptibility were responsible for the variation in symptoms, as in several cases healthy trees were next to those which were heavily defoliated.
Chamaecyparis lawsoniana originates from coastal North America, as apparently the fungus does also, but there are no reports of defoliation associated with S. thujina from this part of the world. Although pathogenicity tests have not been carried out on Lawsons cypress, either here or in Hawaii, we have seen over many years a consistent association of this fungus with a particular set of symptoms, strongly suggesting a cause and effect relationship.
Taxonomic Note : The fungus is now looking for another name. In 1989 Sutton & Pascoe, deciding that the generic concept of was too broad, redefined the genus and excluded a number of species including Stigmina thujina. The assignment of the excluded species to either new or existing genera was left for others to do.
( Margaret Dick, FRI )
DEFOLIATION OF LAWSONS CYPRESS
from Forest Health News No. 50, February 1996
On and off over the past two to three years I have noted Lawsons cypress defoliation on the west coast of the South Island. A large number of samples have been sent to NZ FRI with no clear pathogen being isolated although the fungus Stigmina thujina is consistently found associated with the problem. At first glance the affected stands look as though they may be troubled by wet feet but the trees are on a range of sites and at different locations. Stands which had no sign of defoliation a year ago now look very thin with active needle cast often being seen. Many of the affected stands I have visited for the past ten or so years and up until recently they have been full crowned. If any one has seen recent cast on Lawsons or have any bright ideas I would like to hear from you. (Paul Bradbury, MOF, Christchurch)
