Wider row spacings, new herbicide strategy adds punch to weed fight

A move to a wider seeding row spacing, allowing higher application rates of pre-emergent herbicides, and the addition of a new herbicide strategy has proved a powerful one-two punch in the tough fight against weeds for the Preston family in WA’s northern wheatbelt.

Brothers Bob and Murray grow predominantly wheat and lupins, as well as canola and barley on sandplain country, over their ‘Miranda Plains’ properties, which are situated 80 kilometres east of Geraldton in the south-west corner of the Mullewa Shire.

Some land has been cropped to mainly wheat and lupins for 51 years and the continuing use of herbicides has caused weed control challenges, including reduced herbicide efficacy when targeting annual ryegrass and wild radish.

However, in the last two seasons the Prestons have widened the row spacing on their John Deere paired-row seeding bars from 17.5 centimetres (7 inches) to 25 cm (10 in) and have added a herbicide that can be applied at the early post-emergent (EPE) crop timing, Mateno^® Complete.

Targeting mainly the annual ryegrass in high weed pressure paddocks, the use of Mateno Complete followed the pre-emergent application of trifluralin, which has typically been applied for grass weed control, along with prosulfocarb.

The Preston’s farm consultant, Grant Thompson, Crop Circle Consulting, said the narrow spacings meant lower than optimal rates of pre-emergent herbicides had to be maintained due to the soil throw and, hence, grass weeds had persisted from time to time. However, the wider spacings had since allowed for high rates to be used and the addition of Mateno Complete had complemented the improved weed control strategy.

″Mateno Complete worked in really well with our transition to 10-inch spacings and after so many years of continuous cropping and herbicide use, you are always looking for a new edge to bring into the rotation,″ Bob Preston said.

″It’s about looking years ahead and finding that chemical that you want to move forward with.″

Image: Bayer CropScience Geraldton and Midwest WA Territory Business Manager Courtney Humphrey and farm consultant Grant Thompson, Crop Circle Consulting, inspect the promising grass weed control provided by the early post-emergent application of Mateno Complete herbicide following the incorporation of trifluralin herbicide at sowing.

Mateno Complete, which can be incorporated by sowing or applied EPE in wheat and barley, contains aclonifen, a herbicide mode of action available last season for the first time to the Australian industry, in a unique, complementary co-formulation with pyroxasulfone and diflufenican herbicides.

″The advantage with Mateno Complete EPE is getting 100 per cent coverage over the soil, which means we are not so driven about getting the seeding operation perfect. Before, we were worried about where the pre-emergent chemical was ending up in the seed row, whereas now we can just concentrate on seeding and then the EPE chemical application,″ Bob said.

″Applying Mateno Complete EPE over the soil profile also means we can get back to doing our soil amelioration at seeding the way it needs to be done.″

Up against tough weed populations and the challenge of controlling weeds on some non-wetting sandplain soils, the Prestons have been applying the full label rate of Mateno Complete EPE in wheat.

″We were fairly happy with it last year despite an extremely challenging start and we knew we had to put it on earlier this year and hope that it rained and it did. It wasn’t a lot, but it was enough to get it washed-in,″ Bob said.

″We applied it at the one to two-leaf crop stage, mixed in with bromoxynil and Logran^® to pick up early radish and volunteer legumes. Traditionally we have been going with a radish application early anyway, so the fact we can now add it in with Mateno Complete as well, it works together and we seem to be getting a really good job out of that.

″The tank mixing was also quite good. There was no antagonism and very little crop effect over both years. There was a little bit of paling in the crop, but nothing compared to some other chemistry. It grows out of the paling effect a lot quicker than some of the other early broadleaf chemistry out there that we have used previously. We were very happy with it.″

He said despite Mateno Complete being ″put under the pump″ in high weed pressure areas, they were pleasantly surprised by its control of annual ryegrass that was noticeable at harvest and in the cleanliness of paddocks.

″Mateno Complete is allowing the crop to get that far in front of the ryegrass that we are getting a lot of natural suppression from the crop as well versus our other products.″

″The big thing you look at in a continuous cropping rotation is quite simply how many weeds are there at harvest time, because that then leads into the next three to four crops. The cost benefit of using the product is not just from the one season. Every time you use the product, you have got to run it forward three to four years to assess the investment.″

Grant said non-wetting soils were always problematic in providing an even germination of weeds and, hence, could result in annual ryegrass germinations over a two-month window. However, Mateno Complete was achieving a whole new level of grass control on these soils.

Bob said as a specialist tool, Mateno Complete offered some big advantages.

″Integrated weed management is all about rotation and being able to change things, so whether it’s new chemistry, going EPE and getting 100pc coverage all over the soil, it all adds another benefit. Being able to use Mateno Complete as a tank mix partner with other broadleaf weed control and setting up your crop potential is a big advantage. Its longevity in controlling grass will be a big advantage not only in the current season, but in seasons to follow.

″It’s also not a product that carries over into the following season even in light soils that are ameliorated, so it’s got a lot of benefits and we have to keep establishing it as part of the plan and getting maximum benefit out of every dollar we spend on the product,’’ he said.