New Zealand pollen tests positive for Psa

20 November 2010

MAF Biosecurity New Zealand (MAF) announced this afternoon that samples of New Zealand pollen collected from the Bay of Plenty and South Auckland have tested positive for the bacterial kiwifruit vine disease, Pseudomonas syringae pv actinidiae (Psa). This pollen was collected in 2009 and 2010.

There is no current evidence to show that Psa in pollen can infect healthy kiwifruit vines. MAF’s initial analysis of infected orchards shows that many infected orchards have not used artificial pollination, suggesting other mechanisms of spread may be more significant.

Response Manager, David Yard, says there seems to be no clear link between the use of artificial pollination and the spread of the disease.

“There is no firm evidence that artificial pollination is causing Psa disease. ”

MAF has also tested reference samples of New Zealand pollen collected in the last few seasons. Positive results from 2009 and 2010 samples, and ‘weak’ positive results from 2007 pollen, indicate that Psa may have been present in New Zealand for a number of years. Further testing of historical samples will be carried out.

“These samples pre-date the known application of imported pollen on New Zealand kiwifruit orchards and indicate that Psa may have been present in New Zealand for some time,” Mr Yard said.

Earlier testing of imported Chilean pollen produced a single positive result, which may have resulted from contamination during the sampling process. Subsequent retesting has produced a ‘weak’ positive result on a single sample. The implications of this result are still unclear; however testing of historical samples suggests that this pollen may not be the original source of infection.

On 14 November 2010, MAF advised growers, via the ZESPRI Canopy website, that pollen may present a risk of spread of Psa. MAF cautioned growers on the use of artificial pollination. If the use of artificial pollination is essential to a grower, using pollen collected on the same orchard presents a lower risk than pollen sourced from another property. Growers may wish to ensure that pollen used on their orchards is tested for Psa before they pollinate.

Media contact:
Helen Keyes, Communications Manager
MAF media phone 029 894 0328