A good outcome from early use of broadleaf herbicides in oats despite concerns over potential crop impact is encouraging future applications for a southern WA farming enterprise.
Wellstead Farming is situated in the Broomehill-Tambellup shire in the State’s Great Southern region. In addition to oats, it grows barley and wheat and rotates the cereal phase every year with herbicide-tolerant canola to help control grass and broadleaf weeds.
Cropping manager Duncan Burt, who has worked in the region for 15 years, says the main broadleaf weeds targeted in the cereal phase include capeweed, wild radish and volunteer canola. Reduced effectiveness of Group2 (formerly Group B) herbicides over time has had them searching for new options against the weeds.
He says they also faced a situation in their Bannister oats last season, when early weeds became a problem, particularly high levels of volunteer canola in-furrow, due to no opportunity for knockdown herbicide applications before a late April planting.
“We typically have a double knock. Weed pressure is a lot smaller and we apply MCPA LVE at 4 to 8-leaf, but we didn’t have the option to wait that long last year – the numbers were too high,” Duncan says.
“The volunteer canola was shadowing the oats and becoming a big problem. We trialled a light application of some older chemistry, but we were concerned about crop effects, so we talked to our consultant and agronomists, including Tim Trezise (Frankland Rural), and we were put on to Infinity Ultra as a soft option.”
Developed by Bayer, Infinity Ultra comprises a complementary co-formulation of Groups 27 and 12 (formerly Groups H and F) herbicides, pyrasulfotole and diflufenican, and it can be applied from the two-leaf stage in cereals.
“We used Infinity Ultra as pretty much the only option for broadleaf control at 2-leaf plus, and it can be applied up to stem elongation, so it’s a great window for application. It gives the option of going early and late,” Duncan says.“ ere are other options from about 4-leaf, but many have crop effects and we don’t like to hurt early vigour or knock the crop at a later stage.
“Crop safety is paramount to high yielding crops and avoiding knocking the vigour of oat plants is important. We have seen before, when adding Flexi-N (liquid nitrogen) and trace elements, that it can do a lot of damage, so by minimising crop effect, you are giving the crop all of the potential for the highest yield possible.
“By making the most of all rainfall, it gives you confidence that the plant is not held back and is providing as much seed as possible.”
Infinity Ultra was applied in a tank mix with MCPA and Hasten adjuvant, and with a high water rate of 100 L/ha. It was applied through one of Wellstead Farming’s John Deere sprayers featuring ExactApply technology and using 400kpa pressure and a coarse droplet size.
“The tank mix went really well, the conditions were sunny and perfect, and we observed things carefully because it was new to us and we were having to come in with a broadleaf control early,” Duncan says.
“After that one application, we didn’t have to return with another broadleaf spray. The oats weren’t knocked around, the vigour was still strong and the crowding was brilliant. Normally we have to come back with the odd radish plant or escape of Roundup Ready canola*, so we were very happy not having to go over the paddock again.
“We were also concerned about Roundup Ready being difficult to control and eliminate, but we were really happy with the Infinity Ultra taking those numbers right out of the picture. ere were no survivors in the crop.
“Keeping the crop clean and not having competition for moisture made it clear to us that the oats were growing to their full potential.”
He says Infinity Ultra will definitely add to the rotation of chemical groups used at Wellstead Farming in the future.
“We haven’t used a lot of Group H (now Group 27) in the past and we think it can add to the toolbox for our different cereal crops,” he says.
“Infinity Ultra will have a good place for dry-sowing of cereals, so we can control weeds and volunteers early.”
Duncan says the early application and favourable re-cropping pro le with Infinity Ultra also meant there were no plant-back concerns for following seasons.
“We had rainfall of 350-400mm, which is ne for plant-back, and we have no concerns for the following canola crop. Anyone growing lupins or faba beans would also have no concerns,” he says.
*Application for registration for control of volunteer canola with Infinity Ultra has been made. At time of publication, Infinity Ultra is not registered for control of volunteer canola.
