A network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests.
PestNet is a network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests. It started in 1999. Anyone with an interest in plant protection is welcome to join. PestNet is free and is moderated, ensuring that messages are confined to plant protection.
Januaray 2012. PestNet put out an article entitled Kiwifruit disease linked to China by Abndrea Fox that appeared in Stuff.co.nz Business Day. In that article it says that China may be the origin of the bacterial disease that is affecting kiwifruit in New Zealand, not Italy. The method of transfer from China to New Zealand wass not known. However, another report by MAF mentions China (andf also Chile) have Psa, but makes no other comment. There was insuffiicnet information at that time to say more.
In the article, Seeka, the industries largest kiwifruit handler, is reported to want more analysis by MAF to clarify is pollen or other potential “vehicle” for Psa trnsfer had come from China.
A PestNet member questioed whether pollen could be a source of bacterial disease. If proven, it was said that “all exchanges of genetic material, in whatever form, should be stopped!” The member had always assumed that cell cultured plant material is safe for germplasm exchange.
A question was asked: Is there evidence that pollen can be the carrier of bacterial or fungal propagules that can act as instigator of disease? Are there any proven records of virus transmission through pollen?
In response a paper was cited:
Plant pathogens transmitted by pollen
S. D. Card A, M. N. Pearson B, G. R. G. Clover AC
A Plant Health and Environment Laboratory, Investigation and Diagnostic Centre, Biosecurity New Zealand, Ministry of Agriculture and Forestry, PO Box 2095, Auckland 1140, New Zealand. B School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. C Corresponding author. Email:
Australasian Plant Pathology36(5) 455???461 http://dx.doi.org/10.1071/AP07050 Submitted: 7 June 2007 Accepted: 18 June 2007 Published online: 20 August 2007 Abstract
Pollen is a valuable source of germplasm for breeding and has few associated pests compared with other sources of genetic material. This review seeks to assist the development of appropriate phytosanitary measures by considering the pests that are transmitted by pollen. There are no invertebrates, bacteria, phytoplasmas or spiroplasmas that are pollen-transmitted. Only a limited number of fungal pathogens are associated with the pollen of a restricted number of hosts. In contrast, 39 viruses are pollen-transmitted and a further six are tentatively considered to be pollen-transmitted. The majority of these viruses belong to the Alphacryptovirus, Ilarvirus, Nepovirus or Potyvirus genera. Five viroids have also been identified as being pollen-transmitted.
Authorities in New Zelaand are taking the possibility that Psa is pollenbourne very seriously, and is under review, as seen the Biosecurity New Zealand website:
One of the authors of the paper cited above, said that he was not involved in the current Psa work and cannot comment on that specifically, but the review was written in 2007 and based on the information available at the time. Obviously, this doesn’t exclude the possibility that subsequent findings may contradict it. However, based on a knowledge of virus transmission in seed and pollen there is a need to distinguish between infection of seed or pollen and surface contamination. In the later, it may be possible to treat the seed or pollen to eliminate the contamination.
Finally, a member in Guam gave the example of avocardo sunblotch viroid where transmission by pollen is up to 4% (Hadidi et al. 2003. Viroids. Science Pulishers Inc. p.173.