Hold the line on grassweeds this autumn

After a season of good grassweed control, experts are urging growers to keep the pressure on this autumn.

Fields that have seen moderate to high blackgrass pressure may look cleaner after near ideal conditions in autumn 2024 led to effective control, but the seedbank will still harbour countless seeds, warns BASF agronomy manager, Matt Keane.

Matt Keane © BASF

Blackgrass control is a numbers game

Often, controlling blackgrass is described as ‘a numbers game’ and Matt says it is a useful analogy.

“One plant can easily have 10 seed heads and, with 100 seeds per head, it will produce 1,000 seeds in a single season.

“Around 60% of seeds are usually viable, which means a single plant can generate 600 more.

“That’s how just one plant per metre can generate up to six million seeds per hectare ready to chit in the seasons to come,” he explains. 

It is this ability to multiply rapidly which underlines the importance of maintaining efforts even when blackgrass populations are low.

“Wherever there is a history of blackgrass, there’s no such thing as ‘low pressure’.  Its seeds will always be lurking.

“Just one misstep can see a dramatic rise in populations and affect the rotation for years to come,” continues Matt.

 “As we saw in 2023, the weather can disrupt our most impactful cultural and chemical controls, from the creation of stale seedbeds to the timing of pre-emergence herbicides.

“With those odds, it is counterproductive to knowingly reduce them further by deciding not to use all the controls at your disposal.”

© BASF

The true cost of poor control

“From the loss of yield, or having to adapt your rotation, to growing spring crops with lower margins, or increasing the spend on herbicides and cultivations, there’s a significant cost associated with a misstep.”

It is why Matt advocates the use of Luximo^® (cinmethylin) wherever blackgrass or Italian ryegrass poses a threat.

“Ensuring you have the right product, and one you trust, is even more important in areas where growers have worked hard and spent significant time and money to reduce populations.

“Consciously compromising programmes by choosing lower cost chemistry with lower efficacy, can cost more in the long-term,” he says.

Alongside using the best chemistry, Matt strongly recommends using cultural controls like delaying drilling, stale seedbeds and timely applications of herbicides.

“For Luximo, that is at pre-emergence. While there is flexibility on the label which enables use of the product at peri-emergence, the best control is achieved when it is applied pre-emergence.”

© BASF

Luximo^® in the field

For Suffolk grower, Robert Dyball, stale seedbeds, late drilling and timely applications of herbicides have helped to bring blackgrass back under control following a ‘misstep’ caused by the wet weather in autumn 2023.

Robert manages 263ha of arable land at Elmswell. There’s 80ha of lighter sandy Breckland alongside 160ha of fairly heavy clay.

Across the acreage he is growing Bamford, Beowulf, Redwald and Extase but is planning on moving to soft wheats due to the premium.

“On the heavy land I historically grew two wheat crops followed by oilseed rape, but cabbage stem flea beetle has made that too risky, so now it is continuous wheat with some SFI options.”

Despite the confines of the rotation, Robert uses all the tools available to him.

By paying close attention to detail and using the most effective chemistry, he has successfully curtailed the blackgrass population this year.

“Drilling later is essential,” he says. “I have been pushing back drilling date and now aim to go in mid-October but I also believe in investing in robust herbicide stacks”.

Robert first saw Luximo^® pre-launch and had trials on his farm. His first autumn application was last year, when he applied Luxinum^® Plus with Avadex^® Factor (tri-allate).

“Liquid Avadex can be included in the tank mix, and with a 28m row width, it is difficult to find a contractor to spread the granules,” he explains.

“Having tried other chemistry in the past, I think the Luxinum Plus in particular has done a very good job this year, and I’m pleased with the level of control, especially given the high pressure caused by the previous year.”

Both Robert and Matt agree, Luximo^® is the most effective pre-emergence herbicide available and despite some areas seeing a lower weed count than last year, the right approach is to continue to monitor and invest in cultural and chemical controls, protecting yield this year and beyond.