Focus on herbicide tolerance

These information bulletins contain details on the two new wheat varieties. Soon these bulletins will contain details on the herbicide tolerance of new varieties.

Growing a new crop variety can always seem risky. The good news is the risks will become less, thanks to new research results on how varieties react to different herbicides.

The results are coming from the testing of wheat, barley, oats, chick peas, canola and linola at four sites in South Australia. The work is underwritten by growers through the GRDC and the SA Research and Development Institute.

Growers recently had the opportunity at a field day on Dennis Dall's property Kybunga to see for themselves how old and new wheat and barley varieties cope with standard and double rates of pre- and post-emergent herbicides.

According to SARD1 senior research officer, Steve Jefferies. the upsurge in the use of chemicals makes it vital that growers have the latest information on a variety's sensitivity to chemical damage. He said the damage can manifest itself in yields.

"Both researchers and farmers have considerable evidence that different varieties can react differently to a range of herbicides," he said.

"For example, the Durum wheat variety, Yallaroi, can be more sensitive to pre-emergent sulfonyl-urea herbicides, while barley varieties have different levels of tolerance to the diclofop-methol herbicides.

'The idea is to make sure that new varieties released are not particularly susceptible and, if so, that appropriate warnings are provided," said Mr Jefferies.

Potential new wheat and barley varieties are being compared with standards such as Machete and Galleon in trials at Kybunga.

On Eyre Peninsula chick pea varieties are being compared at Tony Head's Cockaleechie property, and oats at Robert McFarlane's Wanilla property.

In the south-east, Department of Primary Industries and SARDI agronomists are measuring the effect of herbicides on new and old canola and linola varieties. This year field peas, lentils and faba beans will be added to the tolerance evaluation program.

"Until now, new varieties haven't been screened for herbicide tolerance in SA," Mr Jefferies said. "Largely it has been farmers who have been doing it by trial and error — they have run the risk. What this program will do is to cut the risk factor for farmers."

Mr Jefferies said that as well as evaluating recommended herbicides, some non-registered treatments were also under scrutiny.

For example, the herbicides Broadstrike, Eclipse and Jaguar were not registered on oats but were being tested to see if they were suitable and whether registration should be pursued.

Registration is being sought for a mixture of Diuron and Dual used for post-seeding emergent weed control in oats.

Mr Jefferies said the work on herbicides includes details on breeding, yield, disease resistance, nutrition requirements, herbicide tolerance, grain quality and sowing recommendations such as appropriate time, rate and depth of seeding.

Brochures will become available from certified seed producers, at field days and from Departmental offices. The first two of these, providing details on the new wheats. Trident and Stiletto, have just been published.