Medics resist aphid advances

Two new aphid-resistant medic cultivars, Mogul and Caliph, are now with seedgrowers, where both are performing well.

"Caliph has a lot of pluses," said grower Barry Harvie, who grew 20 ha this year for seed on 'Braeside Farm' near Appila. South Australia.

Mr Harvie crops about 300 ha and has grown medic as a pasture and as rotation with wheat, but this is the first time he has grown a medic commercially for seed.

"It has aphid resistance, and of all the medics seems to have far more winter growth — a great advantage for grazing," he said.

Early maturity

"It is also early maturing, so we will always get a seed crop. It seems well suited for our medium to dry rainfall area."

Roger Johns, who crops 800 hectares near Maitland on the Yorke Peninsula has grown both Caliph and Mogul for seed on his property 'Dalwhinnie' and believes both show great promise.

"Both varieties have yielded well and shown resistance to blue-green aphid, which are the main problem here," said Mr Johns.

He singled out Mogul for its "terrific growth" and its extended season. "It will probably prove to be the densest, most leafy medic we can grow, and it also hangs on late, giving an extended pasture feed.

"Both varieties have few spines in the barrel, which makes for clean wool," Mr Johns said.

Potential replacements for Jemalong and Harbinger AR are also about to enter the final stages of evaluation, for possible release in 1995, under a project funded by growers through the GRDC. The project aims to breed medics for the drier parts of southern Australia. It involves collaboration between the Western Australian and South Australian Departments of Agriculture.

World first for burr medics

Breeder Andrew Lake of the South Australian Research and Development Institute said that, in a world first, researchers have created a hybrid between burr medics and Medicago murex. The hybrid appears to have greater blue-green aphid resistance. Burr medic cultivars with some resistance to cow-pea aphid are also being evaluated.

Researchers have also launched a search for a medic resistant to broad spectrum herbicides. Medics are

extremely prone to herbicide damage. Mi Lake said that in this respect M. orbicularis looks promising over a range of environments. A top seed yield of 1.7 t/ha was obtained in trials.

One line of M. sphaerocarpus was outstanding over a range of mid-rainfall sites. It is being seed increased for projected release this year.

The breeders have also completed initial evaluation of extended cultivar collections from low rainfall sands and sandy loams in Greece, Spain, Morocco and South Africa.

CONTACT: MR Andrew Lake 08 266 8493

Region National, North, South, West