Annual meadow grass and sterile bromes can significantly impact on the yield potential of newly planted winter cereals, if not controlled now.
According to Teagasc tillage specialist, Ciaran Collins, this autumn has given tillage farmers a favourable window for planting winter cereals.
“This is a welcome change from the challenges of recent years, but now that crops are in the ground, it is time to focus on weed control.
“For the best results, growers should tackle weeds early with a pre-emergence or early post-emergence herbicide application, especially for tough grass weeds,” Collins said.
The target of autumn weed control is to control weeds that are most damaging to yield and weeds where spring herbicide application will be least effective.
“In particular, sterile brome in winter barley and annual meadow grass in both wheat and barley are high-priority weeds if they are present in fields,” he added.
Annual meadow grass and sterile bromes
The Teagasc representative points out that no herbicide offers full control of brome in winter barley.
But early post-emergence application of products containing Flufenacet/PDM can help if no pre-emergence treatment was applied.
If growers did apply a pre-emergenct herbicide, a follow-up can boost control, though only can about 50-60% effectiveness can typically be expected in winter barley.
The strategy for brome control in winter wheat is different. Flufenacet/PDM can give some control but there is a spring follow-up option of Broadway Star/Pacifica.
“Therefore, the best strategy is to target annual meadow grass in the autumn and follow up with alternative products for brome,” Collins said.
Meanwhile, it has been shown that applying residual herbicides to control annual meadow grass up to early tillering of the weed stage offers the best chance of success.
Once annual meadow grass starts to tiller, it becomes more difficult to control.
But it’s very much a case of being cautious with post-emergence spring options in wheat. This is because AMG is increasingly resistant to certain herbicides like ALS-Pacifica Plus.
“Testing by Teagasc has confirmed resistance, making timely autumn applications even more critical, especially for annual meadow grass that thrives in open, wet conditions like those experienced last year.
“Getting on top of weeds now will help ensure a cleaner crop and better yields come harvest,” Collins stressed.