Pasture renewal aids pest-free outcome

Date: 2009-02-01 | Category: Resources

Pasture renewal provides the opportunity to eradicate pests and diseases from pasture. Altering pest and disease populations is a double-edged sword in pastures.

Removing grass grub and porina populations through cultivation provides short-term benefits but significant medium term costs when pastures are re-infested.

Grass grub populations are normally low when a pasture is established but increase predictably to a peak in 2-5 years.  These populations then collapse due to bacterial invasion, starvation and other biological factors.

Traditional pests such as grass grub can have a significant impact on the outcomes of pasture renewal.

In an irrigated pasture in Mid Canterbury the establishment of a new pasture by direct drilling resulted in an average annual yield of 13,100kg DM/ha over the following three years, a decrease of 2100kg DM/ha.

Much of the variation between positive and negative results comes from the establishment period and grass grub attack during year 3.

Ryegrasses with the new endophyte AR1 and AR37 have been compared to wild type endophtye over 3-4 years at six sites throughout New Zealand.

Total drymatter production of AR1 infected ryegrass was not significantly different from ryegrass infected with wild type endophyte, while ryegrass infected with AR37 endophyte was 9% greater than wild type infected ryegrass, improved protection against black beetle is not always robust.

Published courtesy of Country-Wide - May 2008. An edited extract from AgResearch's Literature Review.

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