Farm Forestry New Zealand
PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Detection of Nectria fuckeliana in pruned and unpruned trees
Scion is the leading provider of forest-related knowledge in New Zealand
Formerly known as the Forest Research Institute, Scion has been a leader in research relating to forest health for over 50 years. The Rotorua-based Crown Research Institute continues to provide science that will protect all forests from damage caused by insect pests, pathogens and weeds. The information presented below arises from these research activities.
From Forest Health News 167, October 2006.
As reported in Forest Health News 165 August 2006, a DNA-based method was used to detect the presence of Nectria fuckeliana within pruned and unpruned Pinus radiata. Currently, it is hypothesised that N. fuckeliana enters the tree through pruning wounds; however, the results of the DNA study suggested that pruning wounds are not required for infection by the fungus, as there was no significant difference between pruned and unpruned trees with respect to the presence of the fungus. These results were unexpected and before forest managers become concerned over the results, we would like to reiterate that the findings of the study are preliminary.
Currently, we are reassessing the robustness of the DNA-based technique that was used in the study. We are confident in the technique but, given the results of the study, we feel that further confirmation of the specificity of the technique is warranted. It is possible that the PCR-based method detected another fungus in the wood; therefore, DNA isolated from pure cultures of other wood-inhabiting fungi is currently being tested. PCR products from the positive samples have also been sequenced and checked against GenBank sequences to ensure that they are N. fuckeliana sequences. Results to date confirm that the technique is robust, but we will continue checking.
Another potential source of error is cross contamination in the laboratory during the DNA extraction process or during PCR. Although all reasonable care was taken in processing the samples and cross contamination is very unlikely, it is still a possibility.
In February 2007, we will be returning to Dunedin to resample the trees that were selected and tested in 2006. During the second assessment, we will be visually scoring the presence or absence of fluting and will also take further samples from every tree that returned a positive result at the first screening, as well as selected trees that were negative. In addition to extracting DNA and testing with the PCR method, we will also attempt to isolate the fungus into culture.As with all scientific endeavours the results of the study have raised interesting questions. We are looking forward to the results from the second sampling in 2007 and are hopeful that we will be able to confidently draw conclusions from the research.
The co-operation of City Forests and Wenita Forest Products in providing and maintaining the study sites is much appreciated.
Tod Ramsfield and Matt Power
This information is intended for general interest only. It is not intended to be a substitute for specific specialist advice on any matter and should not be relied on for that purpose. Scion will not be liable for any direct, indirect, incidental, special, consequential or exemplary damages, loss of profits, or any other intangible losses that result from using the information provided on this site.
(Scion is the trading name of the New Zealand Forest Research Institute Limited.)
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