Growers are been asked to remain patient and wait until the second half of October before sowing in fields with a known blackgrass burden. Good soil moisture and temperatures should then result in positive results.
Last year, the dry August and September led to many cultural controls being less effective. Reduced crop competition from the cold wet spring resulted in many feeling like they had taken a step backwards.
“With the moisture we have, grass weeds are emerging fast in stale seedbeds,” said Tim Horton, technical manager for combinable crops at Agrii. “This is an excellent opportunity to reduce populations before the drill enters the field.
“In fields known to have a higher burden of grass weeds, I recommend not drilling until at least the 20th of October if farmers feel they can hold on until then. Ideally, those fields have been set up with early cultivations to encourage a flush of weeds before drilling, and the drill is not moving too much soil to stimulate fresh germination.”
Mr Horton advised that farmers maintain high seed rates and use more competitive varieties to increase competition. Agrii screens varieties for grass weed competitiveness as part of its variety sustainability ratings (VSR) to advise growers.
“The most competitive wheat varieties, according to our VSR trials, are Skyfall, Tapestry and Astronomer. However, the most widely grown varieties like Champion, Dawsum and Extase are ranked one step behind these,” he said.
“For those farmers that are eager to begin drilling, then I would encourage them to start with the fields with the lowest grass weed populations and finish with the known problem fields,” explained Hank King, UK and Ireland business manager for Gowan.
“Even following reasonable cultural control, pre-emergence herbicide programmes will be crucial this autumn. We learned a lot about what combinations worked best last season following the introduction of new herbicides.
“Mixing modes of action adds to control. The base product for a herbicide programme can be changed depending on the weed pressure. A higher weed burden and farmers may want to go for newer chemistry, but a flufenacet mix may be sufficient for reduced populations.
“A consistent observation from trials, including last season, is that efficacy increased whenever Avadex (tri-allate) was included in the programme. It is a tried and tested product, and farmers can be confident it will reliably increase grass weed control,” said Mr King.
Concluding, Mr Horton noted that his programmes will be based around Luximo (cinmethylin) plus a partner, like Pontos (flufenacet + picolinafen).
“I would top this up with additional flufenacet, or where a farmer can apply it, Avadex,” he said. “If brome is an issue, then I would ensure Avadex is applied.”
“This programme worked well last year, but there were some late flushes once the rains finally came. I expect even better control with our higher soil moisture this autumn.”