New weed control option in oats brings benefits

Having limited broadleaf herbicide weed control options in oat crops has not been ideal for many farmers, so when Western Australian grower Tom Smith was advised of a new solution by his local agronomist, he jumped at the chance to adopt it – and he welcomed some added benefits.
 
Tom, his younger brother, Matt, and sister, Grace, together
with their parents, Alan and Jo, farm properties at Northam, Meckering and Toodyay. They grow wheat, export oaten hay and canola, while they also run about 3,200 ewes and 1,000 dry sheep.
 
The hay is directed to the local Bodiam hay and straw facility, with a large amount then consumed by the Chinese feed market. Tom said doublegee was one of their main broadleaf weed targets in oat crops, together with wild radish, and they had previously used the Group C and I herbicide, Broadside®, to combat them.
 
However, following advice from local Landmark Agronomist Karrie Stratford, they started applying Precept® herbicide soon after it was registered for use in oat crops.
 
“Broadside is a good brew, but we have had to keep rates
up high and we mix it with Flexi-N® (liquid fertiliser) and it has scorched crops a bit – it has been a bit hot. Flexi-N always goes on with our broadleaf sprays at about 40-50 L/ha,’’ Tom said.

“We’ve also possibly had a bit of phenoxy (Group I) resistance in some weeds out at Meckering.

“Karrie then introduced us to Precept.’’

Precept, from Bayer, uses a combination of pyrasulfotole and MCPA LVE. The pyrasulfotole provides robust, three-way activity on broadleaf weeds, while the MCPA LVE provides the capacity to control more mature weeds and higher weed densities.
 
Precept is effective against wild radish resistant to Group B, C and F herbicides and it also provides excellent crop safety in oats.

“We had been pushing the same old chemical for a few years. Before Precept became available for oats, just about the only thing we could use was Broadside,’’ Tom said.
 
“The crop growth stage also had to five-leaf for applying Broadside, whereas with Precept we can spray at three-leaf.’’

 Karrie said mixing up the herbicide mode of action applied, the ability to spray earlier onto smaller weeds, particular when phenoxy resistance was suspected, and the fact Precept was “soft’’ on crops, including when applied with urea ammonium nitrate (UAN), were key benefits.
 
Tom said the weed control achieved by Precept has been impressive.

“It worked great. The paddocks were as clean as a whistle. If there was a weed around, I would tell you – it has done a really good job.’’
 
“The weeds have been quite small when we have sprayed and we have gone with rates of around 1.1-1.4 L/ha. With Broadside, 1.4 L/ha was okay, but going down to 1 L/ha was not enough.
 
“The Precept worked out at about $22/ha, whereas Broadside at 1.4 L/ha was around $30/ha, so we had a $5-$10/ha saving, which is significant.’’
 
The improved weed control has also contributed to excellent Mortlock and Williams oat crops in recent seasons.
 
Karrie said for broadleaf weed control in wheat crops throughout the wider region, the preference would be to use Velocity® herbicide, particularly where there are weeds with resistance to phenoxy herbicides.
 
Velocity is also based on pyrasulfotole and includes bromoxynil and Bayer’s crop safener, mefenpyr-diethyl.

“We believe there is more phenoxy resistance in the region than may be recognised – and there is no known resistance to HPPD inhibitors,’’ Karrie said.
 
Tom said that fortunately with hay playing a significant role in their cropping program, it had also proven to be a good tool for controlling weed seed set and they were still achieving good results from applying Jaguar / MCPA LVE for broadleaf weed control in most of their wheat crops.

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