What a warm winter means for spring weed control in combinable crops

Following a long-overdue favourable autumn and winter for combinable crop establishment, minds will soon be turning to spring weed control.

The wheat area in England rose by 28% in 2020 to 1.62m hectares, and the AHDB estimates that even more was planted last autumn. This means around 1.8m hectares will need to be assessed for herbicide applications.

With wheat currently commanding over £200/t, there is a strong incentive to invest in securing good yields this growing season.

Early indications are that the weed burden in cereal crops is limited. Drilling conditions were favourable, and dry winter soils allowed sprayers to travel late into the year to give residual programmes the best chance to take e ect.

Alister McRobbie (pictured), cereal herbicides product manager for Corteva Agriscience, said: “Following good conditions for autumn residuals in 2021, some might question the need for a contact herbicide for grassweed control this spring.

“But the warmer autumn will have had an e ect on residual herbicide stacks, meaning they will run out of steam earlier – allowing grassweeds to germinate later in the season.”

Mr McRobbie added that some farms experienced issues with product availability which could have a knock-on e ect this spring.

“The reduced availability of glyphosate predrilling meant that many growers were unable to spray o emerging grassweeds prior to drilling, resulting in a greater weed burden going into the winter,” he said.

He advises a spring application of a contact graminicide to control grassweeds and protect yields become a priority to prevent yield loss, because a broad spectrum of grassweeds also germinate as temperatures begin to rise in the spring.

“Broadway Star gives excellent control of brome species, rye grass and wild oats in winter wheat,” Mr McRobbie suggested. “It is also e ective against a wide range of broad-leaved weeds. Using in conjunction with a robust pre-herbicide residual programme, it provides robust control going into the key period of the growing season. “For best results, include a recommended adjuvant and always target weeds when they are small and actively growing, and don’t spray when it is cold as e cacy will be reduced. A good rule of thumb is that if the grass is growing and needs a cut, it’s probably suitable for applications of Broadway Star.”

Early applications for sterile brome control will bene t from tank-mixing with pendimethalin to provide some residual control where there is the potential for further germination.

Broadway Star will also control a range of di cult broad-leaved weeds such as cleavers, groundsel, brassica weeds, pansy, poppy and speedwell. In addition, 265g/ha of Broadway Star plus an adjuvant will control umbelliferous weeds such as bur chervil and shepherd’s needle, provided the weeds are small at application.

“Some farmers may have missed the fact that Broadway Star now has approval for use in spring wheat. It can be applied at 200g/ha plus an adjuvant to target wild oats and broad-leaved weeds too,” Mr McRobbie shared. favourable, and dry winter soils allowed sprayers programmes the best chance to take e ect.

programme, it provides robust control going into the key period of the growing season. recommended adjuvant and always it’s probably suitable for applications of

High-value oilseed rape crops will need attention soon

The picture is similar for oilseed rape growers. Many crops are quite forward following the warm weather and early drilling strategies which have been widely implemented to across the UK.

“Conditions were good for applications of propyzamide chemistry, which has helped clean up elds and the oilseed rape crop looks encouraging at this stage,” Corteva’s oilseed rape herbicides category manager, John Sellars, said.

Oilseed rape prices have soared, and plantings have increased by almost 13% to 345,000ha.

“It’s a crop worth investing in, and when temperatures start to warm up in the spring the targets will be those weeds that steal yield and cause issues at harvest,” Mr Sellars continued.

From 1st March, applications of Korvetto will have strong activity on these weeds; cleavers, mayweed and thistles in particular.

Mr Sellars said: “Even farms which apply good autumn herbicide programmes in a timely manner will usually face a late winter and early springgerminating broad-leaved weed burden.

“Korvetto will be a very good option because it will control many of the weeds found in oilseed rape crops as daylight hours increase and temperatures rise.” FG

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