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Pre-emergence weed control in pulses “crucial” as toolbox diminishes

Pre-emergence weed control in pulses “crucial” as toolbox diminishes.

An extremely wet start to the year may mean soil conditions are not, suitable for spring drilling until well into March in some places.  

The PGRO is advising pulse growers to focus on applying well-chosen pre-emergence herbicides this spring as post-emergence options are limited and to be guided by the soil conditions rather than the calendar when considering drilling.

But when conditions allow, the PGRO’s Principal Technical Officer, Jim Scrimshaw, says it is important to get the herbicide programme right. 

“Making the best effort to control weeds reduces the impact of them depriving the crops of space, light and water, particularly when peas and beans compete so poorly during their early development,” Jim said. 

“We don’t have many active ingredients to play with but used wisely, and with a little good fortune with the weather, they can do a job in most situations.”

Consider reducing rates to control costs

Today’s weed control products can be fairly expensive so growers need to do all they can to get the best out of them. 

Jim said: “In an attempt to control costs, we can reduce rates – however, it will mean a lower level of weed control. 

“The repercussion may be a reduction in yield and excessive green material slowing down your harvesting operation. Crops ripening unevenly is also a possible consequence. Getting rid of excess green material or tackling an uneven crop is now not quickly remedied and may mean increased drying costs.”

Jim suggests growers should evaluate the pros and cons to strike a balance between reducing rates and the likely penalties of doing so. 

Get to know your weed species – and choose products accordingly

Having an idea of the weed spectrum that typically appears on your farm can help guide you when deciding which products or combination of products will work best. 

“Remember to use appropriate rates and apply in an appropriate volume of water,” Jim adds.

Slow down the sprayer and consider boom height

“We want an even application of herbicides and we don’t want any of it to drift away – as soon as it does, we’re not applying the intended rate and we’re losing money. 

“If using appropriate nozzles and you are able to reduce the boom height this should lessen the amount of drift and slowing down with some of these big sprayers will improve the stability and improve the coverage of the soil surface,” Jim commented.

Delay the herbicide?

In extended periods of dry weather where no rainfall is predicted following drilling, delaying herbicide applications is something to consider. 

Jim said: “There is a risk here, but you can potentially avoid losing herbicide activity during the dry spell when few weeds are likely to germinate.” 

Follow bentazone stewardship guidelines

Post-emergence options are few and the main post-emergence active ingredient for pulse growers – bentazone – is under threat.  Too much, too often is being detected in water. 

Jim said: “If amounts detected in water are not seen to be decreasing by the time it comes up for re-registration in 2024, then we could well lose it, which is why it’s crucial that we all follow the stewardship guidelines.”


Notes to editor

The PGRO is a non-statutory levy body supported by our grower members, the UK trade and also by a substantial amount of outside funding for our research work. This is carried out both on our own and in partnership with UK, European and worldwide research, and commercial organisations. As the UK's centre of excellence for peas and beans, the PGRO has a long and highly valued track record of providing authoritative, up to date information and project work based on solid, reliable research.

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