Keep an eye out for beetles

Media release for immediate use

26 October 2007

Keep an eye out for beetles

Farmers should keep their eyes out for grass grub beetles in flight now and through to early December The activity of grass grub beetles in flight at dusk and during the early evening will give a strong indication as to the likely risk of pasture infestation with grass grub larvae later in autumn. Once established in pastures, grass grub populations can grow rapidly, as most of their eggs are laid within a short distance of where the adult beetles emerge.

The grub’s voracious appetite can be devastating to a farm’s productivity, with the cost to New Zealand’s agricultural industry estimated at $90 million a year in lost revenue. The beetles can also cause significant problems for cropping and horticultural crops, stripping plants of leaves during their brief but damaging feeding flights.

Ballance Agri-Nutrients Head of Agro-Sciences Warwick Catto says the warmer weather over the winter and early spring period will have provided ideal conditions for the beetle’s growth and as a result we could see high numbers this year.

‘It’s reasonable to deduce that where you see the beetle in flight, you will find larvae in the soil nearby. If you have beetles, then I would advise booking a space in your diary during February to have someone check your farm for larvae infestations. Ballance Technical Sales Representatives can carry out this inspection and recommend the best treatment.’

Mr Catto says while there are a number of ways farmers can deal with grass grubs, on-farm results backing the economics of bioshield grass grub make a compelling argument for a biocontrol method for managing this pest.

‘For grass grub, that control agent is a bacterium isolated from New Zealand soils. When it’s ingested by the grubs, it causes them to die from amber disease and actually sets up a continual cycle of infection in the soil, that will persist for up to five years.’

Based on experiments on grass grub-affected farmland in the central North Island, AgResearch was able to develop a model that showed the difference in net return that could be achieved by treating the pasture with bioshield grass grub (see graph below).

The model’s results show how, four and five years after sowing, treated pasture can yield more than twice the net return/ha of untreated pasture.

Actual returns for any pasture will depend on farm management practices and the land’s production potential, but left untreated, grass grub will definitely eat into profits, along with grass and clover roots.

Ballance’s unique biocontrol product bioshield grass grub offers a long-term solution to this devastating pest.

Bioshield grass grub is made from a naturally occurring soil bacterium and food-grade ingredients, making it a good choice for those looking to reduce agrichemicals on-farm.

ENDS

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