sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDU Faculty of Forestry Journal
Serial: A, Number: Special Issue, Year: 2009, ISSN: 1302-7085, Page: 136-140
AN OVERVIEW OF POTENTIAL INFECTION COURTS FOR Neonectria
fuckeliana, THE CAUSAL AGENT OF NECTRIA FLUTE CANKER IN
Pinus radiata IN NEW ZEALAND
ABSTRACT
Anna J.M HOPKINS 1* , Patricia E. CRANE 1 , Margaret A. DICK 1
1 Forest Protection, Scion, Private Bag 3020, Rotorua 3010, New Zealand
* Anna.Hopkins@scionresearch.com
Nectria flute canker is a disease of Pinus radiata stems in the southern parts of New
Zealand caused by the pathogen Neonectria fuckeliana. Although tree crowns generally
remain healthy, stem cankers and associated defect reduce the commercial value of the
timber. In Northern Hemisphere countries where N. fuckeliana is endemic, open wounds,
dead attached branches and branch stubs have been identified as the primary infection
courts for N. fuckeliana. In New Zealand the development of the Nectria flute canker
disease is primarily associated with pruned branch stubs however recent studies suggest
that this is not the only possible infection court as the fungus has been found in trees prior
to pruning. Three separate field trials were established to examine potential infection courts
for N. fuckeliana in P. radiata in New Zealand. These infection courts included stem
wounds, pruned stubs, branch crotches and branch collars. Stem depressions, the usual
precursor to flute cankers, were created following inoculation of deep and shallow stem
wounds and of some branch collars. Inoculation directly into pruned stubs resulted in only a
few, small stem depressions and the fungus was largely contained within the branch trace.
Infection through branch crotches was not successful. Both inoculation types tested
(ascospores and conidia) resulted in similar canker development and fungal spread within
the tree. The trials described in this paper are ongoing.
Keywords: Neonectria fuckeliana, stem cankers, Pinus radiata.
1. INTRODUCTION
Pinus radiata D. Don is the most important plantation tree species grown in New
Zealand, comprising more than 89% of the plantation estate (NZFOA, 2009). Many of
the plantations are managed to produce clear, knot-free wood by pruning from one to
three times during the rotation (NZFOA, 2009). Stem cankers, often associated with
pruned stubs, have become increasingly noticeable in some Pinus radiata plantations
in the lower South Island of New Zealand over the last 15 years (Dick and Crane,
2009; Gadgil et al., 2003). The long, narrow cankers, commonly referred to as “flute
cankers” for their elongated appearance, can extend for several metres above and for a
shorter distance below a pruned branch stub. Formation of cankers associated with
natural injuries on the stem internodes has rarely been observed (Dick and Crane,
2009). Although tree crowns generally remain healthy, affected trees are susceptible to
decay, to wind breakage at infected whorls, and wood quality can be affected.
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