17 March 2011

2 minute read

Oceania

The discovery could ensure more persistence for sub-clover, the most popular pasture legume across low and medium-rainfall areas and also a favourite fare of the red-legged earth mite.

Autumn and early winter sees the mite causing the most damage to pasture seedlings. To date, the only way to curb their destruction was to apply pesticide.

But Dr Phil Nichols, subterranean clover breeder with the Department of Agriculture and Food Western Australia (DAFWA), has bred two mite-resistant sub-clover varieties, which then underwent testing in field trials across southern Australia. The varieties are now commercially available.

Dairy Australia, through the collaborative body Pastures Australia, has supported the research overseen by the Grains Research and Development Corporation and Australian Wool Innovation Ltd.

Dr Nichols said the resistant varieties could mean a more cost-effective way of reducing losses from mites.

It could also curb potential resistance to widely-used insecticides, he noted.

The two varieties – Rosabrook and Bindoon – are the result of a breeding program that started in 1992.

In trials they suffered significantly less damage at low mite density than other sub clovers, although damage was similar when mite infestation was high.

However, early season performance of the two new varieties suggests that their resistance is enough to have a positive effect on pasture productivity in most seasons.

Over three seasons Rosabrook had higher seedling densities, produced more winter feed and set more seed than Denmark and Mount Barker at six high-rainfall sites, while Bindoon outperfomed Seaton Park and York at six medium-rainfall sites.

Dr Nichols said the new varieties have the benefits of producing more early season feed - the time when feed supply is in greatest demand- in addition to their effects on reducing mite damage. This in turn should lead to greater milk production.

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