Growers are asked to check their crops for Lettuce aphid (Nasonovia ribisnigri). Photo courtesy of NSW Department of Primary Industries.

The State’s lettuce growers are being urged to check their crops for the serious pest lettuce aphid after the detection of the pest north of Perth this week.

Aphid-infested lettuce leaves were provided to the Department of Agriculture and Food for identification, and the pest has been confirmed as lettuce aphid.

Lettuce aphid has not been previously found in Western Australia and the infected crops will be sprayed within the next 24 hours.

Growers in the Perth metropolitan, Albany, Mt Barker and Manjimup regions are being asked to be on alert for the pest.

Department entomologist Mike Grimm said lettuce aphid could be hard to detect as it usually fed hidden in the centre of the lettuce heads.

“Occasionally the aphid also feeds on the outer leaves, but generally prefers to feed on new leaves deep inside the plant,” he said.

Mr Grimm said adult aphids grow to 2.7mm long and are green in colour with black stripes.

“The juveniles may also have the stripes. Their legs are quite spindly, giving them a spider-like appearance,” he said

 “In large numbers, the aphids can cause young plants to be stunted and leaves to become pale in colour and slightly deformed making them unacceptable to sell. The presence of the aphid in lettuce renders it unsuitable for sale.

“Additionally, the lettuce aphid can also become a vector for a number of viruses, including gooseberry veinbanding virus, cauliflower mosaic virus, cucumber mosaic virus and lettuce mosaic virus.

“Due to this increased disease risk we are strongly urging growers to monitor their crops and report any suspected aphid activity to the Department of Agriculture and Food.”

Vegetables WA and Potato Growers Association executive officer Jim Turley said Vegetables WA, in conjunction with the Department, was arranging meetings with growers to provide information on how to treat lettuce aphid infestations.

Lettuce aphid was first detected in Tasmania in 2004, Victoria in 2005 and New South Wales and South Australia and Queensland in 2006.  To date, only the Northern Territory remains free of lettuce aphid.

Industry and the Department worked together in response to the detection of this pest in Tasmania and implemented measures to reduce the risk of introduction of this pest into Western Australia.

The insecticide pymetrozine (Chess™) is registered for in-field control, and imidacloprid (Confidor™) is registered for use in seedling trays against lettuce aphid.

To report suspected lettuce aphid or for more information, contact the Department’s Pest and Disease Information Service on 1800 084 881.