23 Mar 2015

Mesh cover to fight potato pests

7:56 am on 23 March 2015

New research shows a plastic mesh cover laid over potato crops could be the answer to fighting potato pests without using chemical sprays.

Farmer with basket of organic potatoes.

Photo: AFP

Scientists at the Future Farming Centre and Lincoln University say field trials of the mesh cover is showing exciting results in controlling the tomato potato psyllid as well as reducing potato blight.

Charles Merfield

Charles Merfield Photo: SUPPLIED

The psyllid arrived in New Zealand in 2006 and can cause severe crop loss through its bacterium.

Researchers Dr Charles Merfield said the trials over two growing seasons in Canterbury showed potatoes under the mesh covers had reduced numbers of psyllids, increased tuber size and an increase in overall yield.

He says the covers were widely used in other countries and he expected them to become popular in New Zealand.

"These mesh crop covers have been in use in Europe for probably nearly two decades now, so they're very widely used over there for pest control, particularly amongst organic growers, so these strike me as being an ideal way of controlling psyllids on potatoes on field crops.

"We did some initial trials at the Future Farming Centre and we've got some very good results in terms of controlling psyllid - and we also got the surprise effect of a dramatic reduction in potato blight as well."

Dr Merfield said the mesh could also control a wide range of pests on many different field crops and was being used by organic growers in Hawke's Bay to control root fly on carrots.


Seperately, scientists are investigating how they can use naturally occurring fungi and bacteria as biopesticides to kill insect pests.

Working through the Bio-Protection Research Centre at Lincoln University, they are carrying out field trials against the diamondback moth caterpillar, which attacks crops such as broccoli, cabbage, cauliflower and bok choy.

And a tiny Chilean beetle has been released in Southland to control Darwin's barberry, a thorny weed that scientists say could become as big a problem as gorse if it is allowed to spread.