Aphid plays havoc on lettuce exports

Australia has suspended the importation of some vegetables from New Zealand because of fears they may host the aphid that is tearing the heart out of the local lettuce industry.

The Ministry of Agriculture and Forestry's director of plant biosecurity, Richard Ivess, said Australia had taken "emergency action" to temporarily ban a range of vegetables, including lettuce, artichoke and endives.

"The suspensions will be withdrawn as soon as MAF provides reassurances the commodities are free of the lettuce aphids," Ivess said.

Russell Jordan, head of the Vegetable Federation's fresh vegetable sector, said the lettuce ban had been in place since July, but other industry officials said there had been little economic impact because few whole lettuces went to Australia.

Another MAF spokesman said the latest discussions with Australian officials had left "still under discussion" the issue of other produce considered a host risk.

The new pest, lettuce aphid (Nasonovia ribisnigri), was detected on lettuce at Marshlands, Christchurch, on April 2 and rapidly spread through the South Island.

On May 7, MAF was told it had also turned up at Pukekohe. There, growers said most of them had disposed of infected lettuces and replanted in new areas.

Some have waited to plough under affected lettuces, but have been prevented from moving tractors on the plots because weeks of rain have left the soil vulnerable to compaction.

Crop and Food scientist Dr Marlon Stufkens, who is testing the aphids for resistance to pesticides, said the aphid was not as prevalent in winter, but the real danger could come in spring.

If warm weather brought southerlies, the aphid would spread to South Canterbury - which had so far escaped infestation - and northerlies would put Kapiti and Gisborne at risk.

Gisborne company LeaderBrand Produce, whose East Coast crops have effectively been leapfrogged by the infestations, is one of the nation's main lettuce suppliers to supermarkets. It has spent millions in the past four years revolutionising the fresh vegetable industry with the field packaging of iceberg and romaine lettuces.

New Zealand has about 270 lettuce growers, who plant 1541ha in the crop each year, worth about $26 million.

Jordan said most of the vegetables blocked at the Australian border were exported as salad mixes, which were washed in chlorine and unlikely to contain the aphid.

Dr Stufkens has said work to get pesticides registered by MAF is on track, but is being hampered by problems caused by aphids succumbing to a natural fungal disease.

- NZPA