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Pine pitch canker on imported seed

From Forest Health News No. 67, September 1997.
Results coming through from pitch canker researchers in California indicate that a small proportion of infected Pinus radiata seed carries the fungus deep within the embryo. The screening procedure currently in use in New Zealand for imported pine seed would probably not detect this form of deep-seated infection. This finding raises the level of risk of an introduction of the pitch canker fungus from seed. In addition seedlings germinating from such seed may carry a latent infection for up to 4 months before the disease is manifested. Further precautions are therefore suggested to reduce the risk of an introduction of pitch canker via seed.
• Imported pine seed (unless accompanied by certification that it was collected in a pitch canker-free area) will continue to be screened at the Forest Research Institute prior to release.
• Growers are requested to sow any released seed in a separate area of the nursery so that the material can be inspected following sowing until the risk period has passed.
• The potential for a seed treatment to eliminate intemally-borne infections of
Fusarium subglutinans f.sp. pini will be explored.
( Margaret Dick and John Bain, FRI)

From Forest Health News No. 68, October 1997.

Pine Seed - At present pine seed entering New Zealand is subject to MAF regulation. This stipulates that one of the two following options must be met before imported pine seed can be released:

Option 1 - That the seed be accompanied by a Phytosanitary  Certificate  issued  by  the government of the exporting country with the following endorsements:
Fusarium moniliforme var subglutinans is not known to occur in--(the name of the country where the seed was produced)---".

"The seed has been treated with ----(insert one of the fungicide options below)-----at 2g a.i. per kg seed".

Note: One of the following fungicides is to be used: captan or thiram.

Option 2 - On arrival in New Zealand the seed is to be consigned to:

The Pathologist, Forest Research Institute, Private Bag, Rotorua, New Zealand

to be tested for the presence of Fusarium moniliforme AT THE EXPENSE OF THE IMPORTER.

It is extremely important that if you do not wish to incur the expense of testing and the delay (3-7 weeks for testing) then you should ensure that the exporter fulfils Option 1
. If testing is done then there will be a minimum charge of $200 per seed lot.

Douglas fir Seed - At present the testing of Douglas fir seed is voluntary for the importer. Before you submit seed for testing please contact Forest Health with the following information:

• precise seed harvest location and if possible the latitude and longitude of the collection site.
• the year the seed was harvested.

With this information Forest Health will assess whether the seed should be tested.

Note: The regulations have not kept pace with the name changes and where Fusarium moniliforme var subglutinans and Fusarium moniliforme are mentioned they are referring to what we now call Fusarium subglutinans forma specialis pini .
Geoff Ridley, FRI )

From Forest Health News No. 69, November 1997.
In the last issue of the newsletter (FHNews 68:1, October 1997) the quarantine regulation for the importation of pine and Douglas fir seed was outlined. On 5 November 1997 the regulation was amended with the quarantine status of
Fusarium subglutinans
f.sp. pini being changed to a Risk Group 2 pest - "A quarantine pest which, if introduced into New Zealand, would cause major disruption to market access and/or significant economic impacts on the production of a particular commodity/commodities, and for which some other importing countries require specific pre-export phytosanitory treatment" (MAP RA Standard 155.04.01). This means that pine and Douglas fir seed imported into New Zealand requires a post entry level 3 quarantine facility in which the seeds will be grown for one growing season. A level 3 quarantine facility is a "High Security Facility" and its specification is detailed in the above MAF RA Standard. Note that a permit must be obtained from MAF before importation and that this regulation applies to seed from ALL countries.
Geoff Ridley, FRI)

From Forest Health News No. 70, December 1997 - January 1998.

Researchers in the USA have demonstrated that the pitch canker fungus, Fusarium subglutinans f.sp. pini, can be borne both externally and internally in pine seed. In California it has been found not only in radiata pine seed from infected trees but also on seed from adjacent healthy trees. This result raises questions about the potential for Douglas fir seed collected from trees in pitch canker affected areas to also carry the fungus.

The contamination of Douglas fir seed with a range of Fusarium species is well documented in North America. Although some of the species are known pathogens of Douglas fir (particularly causing nursery diseases), the other species appear to have no role as disease-causing organisms. Much of this contamination can be removed or destroyed by surface sterilisation and by fungicide dusting but a few seeds with internally borne contamination will be unaffected by such treatments. There is therefore a possibility that cones of Douglas fir growing amongst pines in a pitch canker area may pick up F. subglutinans f.sp. pini from the airborne spore load and carry the fungus as an endophyte, even although the Douglas fir may not be particularly susceptible to the disease. Such seed could then transmit the fungus to nursery soil once it was sown. An investigation of the fungal loading of Douglas fir seed collected from pitch canker infected areas is needed to determine, and perhaps quantify, any risk associated with such imported material.

(Margaret Dick, FRI )



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