Mite against mite in maize

Consumer demand for maize or corn products like breakfast cereals and snack food is driving new research by NSW Agriculture that sees scientists pitting mite against mite in a bid to boost maize production.

Predatory mites have been enlisted to test a biological control strategy that has the potential to give growers an effective management tool for the devastating two-spotted mite.

Two-spotted mites feed on the underside of leaves, reducing photosynthesis, which in turn reduces crop yield.   Petroleum spray oils are currently the only method of control available but this is not without its problems as growers find it difficult to get the spray to where the mites are feeding.

NSW Agriculture Entomologist at Tamworth Agricultural Institute, Adrian Nicholas, said mites can cause a lot of damage to maize crops.

"Mites were particularly bad this year in the north-west of the State because of the hot, dry conditions and local growers may find that yields were down by as much as 15 per cent," Dr Nicholas said.

"We hope to improve mite control by providing growers with a biological control strategy that will be easy to use and reliable.

"Predatory mites have already been effective in controlling two-spotted mites in maize in North America and we are confident they will work here - even though we are using different mite species.

"The ones we are using are well known predators of two-spotted mite in Australian glasshouse crops and in field-grown strawberries and vegetable.    They work by seeking out and eating the pests."

Two species of predatory mite were chosen for their environmental preferences - one preferring hot dry weather and the other preferring moderate weather with some humidity.

By selecting a predator that matches the conditions in maize crops, NSW Agriculture is aiming to provide an effective mite management tool.  Early indications are the new strategy is working on the trial site.

"Monitoring reveals that the predatory mites are established and feeding on the two-spotted mites, and we are encouraged by the results so far," Dr Nicholas said.

"However we won't know how effective the mites have been until the end of the season - at harvest."

Further testing will be required before the predatory mites become part of a new control strategy offered to maize growers throughout the State.

Media contact: Adrian Nicholas, NSW Agriculture Tamworth

Issued by: Annette Cross, NSW Agriculture Tamworth

High resolution images are available from Annette Cross