Ross, Ingrid, David and Margot Uebergang have been growing cotton for 27 years at Miles on the Darling Downs. Speaking to their CottonInfo Regional Extension Officer, Ross Uebergang outlined how they are managing the threat of resistant weeds.
They combat a series of weeds each year, in both their cotton and winter crops, including fleabane, feathertop Rhodes grass, barnyard grass, liverseed grass, bladder ketmia, black pigweed, caustic creeper, caltrop, volunteer cotton, milk thistle, fireweed, black oats and phalaris. Bellvine is an emerging problem on the farm, one Ross Uebergang suspects may become a larger problem down the track.
The Uebergangs are yet to do any resistance testing – something Ross hopes to implement this season – but suspect they may have resistant grass weeds.
As a result, they have implemented a whole-of-farm approach to integrated weed management, involving multiple weed-control tactics.
“If you keep relying on one tactic no matter what it is, a problem is going to arise,” said Ross. “We are trying to manage resistance and also the buildup of problem weed seeds. If we don’t, resistant or hard-to-kill weeds will bring the whole farming system unstuck.”
“For us, grasses are the main problem. We have barnyard grass and feathertop Rhodes grass and we’re unsure if they’re resistant or just hard to kill,” he said.
Ross doesn’t rely on glyphosate: his approach includes pre-plant residuals, pre-emergent knock downs, and ‘laybys’ (residual herbicides used to control weeds in- crop), plus non-herbicide tactics including cultivations and spot chipping.
“Our current strategy is to apply a residual six-weeks prior to cotton planting and then to pre-irrigate to allow the volunteers and other hard-to-kill weeds to emerge.
“We follow this with pre- and post-planting knockdowns, which include gramoxone (Group L). In crop, we apply two Group M (glyphosate) sprays and a Group A spray to target feathertop Rhodes grass and will also apply in-crop residual chemicals with shield spray in problem fields.
“After picking, we mulch and rootcut and then do heavy tillage passes to remove ratoon cotton and compaction and then the system starts again. For fields going into fallow, a layby is applied immediately post winter harvest, keeping fields clean for first flush of spring grasses,” said Ross.
“We review our practices every year. Pre-season and post-season we have a meeting with our consultant, Tim Richards of MCA, to review our strategy.
“This is where we work out our rotations and fields, highlight problem areas and develop our residual program. We have a whole farm approach, but treat fields separately due to different weed spectrum and soil types.
“This is our third season of implementing this weed control program and it has really streamlined the whole operation of growing the crop, resulting in greater timeliness of operations which equates to better yields,” he said.
Tim Richards of MCA says a successful integrated weed management system means taking a long-term approach.
“If a grower is looking further ahead than just this season and is willing to commit to a rotation, then it is easy to implement an integrated weed management system like this one. The spin-off benefit of such a system is superior operational timeliness, as we have – and are adhering to – a plan,” Tim said.
|Growers||Ross and Ingrid Uebergang, David and Margot Uebergang, Uebergang Agriculture|
|Cropping area||Total hectares: 1100 ha. Cotton: 400 ha irrigated|
|Soil type||Clay loam, brigalow belah, deep cracking self-mulching clays|
|Rotations||Three-year rotation: cotton (summer); covercrop back into cotton (winter, then summer); barley or wheat (winter); fallow (summer and winter); and cotton (summer)|
Further information: CottonInfo weed management page