Riverina growers of honeydew and rockmelons, tomatoes and soybeans need to be on the lookout for Silverleaf Whitefly (SLW) this coming season, says Dr Sandra McDougall, I&I NSW industry leader field vegetables.

“This 1mm long insect with very white, slightly waxy wings sucks the sap from plants and can cause physiological changes in the plant that can significantly reduce quality and yield,” Dr McDougall said.

“Because it can reproduce very rapidly the developing nymphs can rapidly desiccate a growing plant.”

Silverleaf Whitefly was first observed north of Griffith in the summer of 2008/9 but extended its range last summer to the Griffith and Whitton areas.

It has a broad host range including the pumpkin (cucurbit), tomato (solanaceous), bean (legumaceae) families of plants as well as a number broadleaf weeds.

“Lettuce growers should also look out for SLW,” Dr McDougall said. “They will only be a problem if there are nearby infested crops or weeds because nymphs cannot develop on lettuce but adults will feed.”

Silverleaf whitefly is particularly difficult to manage because it does develop resistance to insecticides.

Current management still largely depends on well applied insecticides but must be accompanied by very good crop sanitation practices such as destroying heavily infested crops, cultivating in crops soon after harvest, and managing surrounding weeds particularly the broadleaf weeds.

In Queensland a parasitoid Eretmocerus hayati has been introduced and is reducing background populations of SLW.  A small release is planned for the Riverina to see if the parasitoid will establish.

“Vegetable growers are invited to an information afternoon at the Gemini Hotel in Griffith on Thursday, October 7 from 1.45 to 5:30pm,” said Tony Napier, district horticulturist at Yanco.

“The first hour is on irrigation management and the second is covering Silverleaf whitefly management.”

Contact Tony Napier, 6951 2796.