sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDÜ ORMAN FAKÜLTESİ DERGİSİ
Neonectria fuckeliana (C. Booth) Castl. & Rossman (Nectria fuckeliana C.
Booth) (Ascomycota: Nectriaceae) is the fungus most commonly found in
association with the flute cankers (Dick and Crane, 2009). This pathogen is thought
to be endemic to Northern Europe, Scandinavia and North America where it has
been recorded principally as a common wound invader or weak pathogen of
species of Picea and Abies (e.g. Roll-Hansen and Roll-Hansen, 1979; Schultz and
Parmeter, 1990; Vasiliauskas and Stenlid, 1998). Pathogenicity of the fungus has
been reported infrequently in Pinus spp., and this has been primarily as the result of
artifical inoculations (Smerlis, 1969). The pathogen has three spore states. In
addition its teleomorph, in which ascospores are produced in perithecia (the
Neonectria phase), two anamorphs are formed under certain conditions: an
Acremonium state with unicellular spores and a Cylindrocarpon state
(Cylindrocarpon cylindroides var. tenue Wollenweber) with multicellular spores.
Vasiliauskas and Stenlid (1997) demonstrated that, in Europe, the N. fuckeliana
ascospores are probably the major dispersal propagules. The importance of the
anamorphs in the pathogen life cycle and in disease development is not fully
understood.
In the Northern Hemisphere, open wounds, dead attached branches and branch
stubs have been identified as the primary infection courts for N. fuckeliana (Roll-
Hansen and Roll-Hansen, 1979). In New Zealand, since the development of the
Nectria flute canker disease is primarily associated with pruned branch stubs, it
was assumed that these branch stubs were the primary infection court (e.g. Bulman,
2007). Recent studies by Power and Ramsfield (2006, 2007) however, suggest that
this is not the only possible infection court for N. fuckeliana. In a study of 90
pruned and 90 unpruned trees, the pathogen N. fuckeliana was found in
approximately 22% of trees and no significant difference in frequency of the
pathogen was found between pruned and unpruned trees. None of the trees
examined showed symptoms of Nectria flute canker. This suggests that N.
fuckeliana is able to enter trees prior to pruning using some other infection court/s.
This paper outlines a number of trials currently being undertaken in southern New
Zealand to identify possible alternative infection courts for N. fuckeliana.
2. INFECTION THROUGH STEM WOUNDS
A field trial was undertaken to examine the importance of different wound types
and inoculum sources for disease development and fungal infection. Specifically
the trial aimed to determine whether pruned branch stubs were an effective
infection court for N. fuckeliana and, following on from Vasiliauskas and Stenlid
(1997), whether ascospores were the most effective inoculum source. Forty-five 6year-old
Pinus radiata were subjected to one of three wound types (shallow stem
wound, deep stem wound or pruned branch stub) and one of three inoculation types
(ascospore inoculation, conidial inoculation or a water control). Trees were
assessed for the formation of stem depressions (the typical precursor to flute
cankers) after 6, 12 and 18 months, after which time they were harvested and the
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