Mounting spring workloads may tempt sprayer operators to rush herbicide sprays but compromising timing or application quality could result in sub-optimal control.
Spraying that was planned for last autumn but disrupted because of wet weather is adding to already hectic spring schedules. While early grass weed control is key, applying products too early, before plants are actively growing, risks inadequate uptake of the active substance while travelling too fast risks missing the target altogether.
“Why compromise the last chance to control grass-weeds?” asks Adam Nears, commercial technical manager for Bayer CropScience.
“Many autumn-sown wheat crops are yet to receive a residual and with so many jobs on the to-do list, many growers will choose to tank-mix a residual such as Liberator (flufenacet and diflufenican) with Atlantis WG (mesosulfuron and iodosulfuron). Trying to control black-grass in a single pass means you have only one chance to get the application right.
“Waiting for active growth is crucial; plants’ metabolic processes need to be in full swing for contact herbicides to be most effective,” he says. “Daytime temperatures alone will not determine active growth; topography, slope, orientation and soil temperatures will all have a bearing.”
When conditions are dry enough for sprayers to travel and black-grass plants are greening-up, Mr Nears encourages spray operators to keep forward speed at 12kph or below.
“Any faster and spray quality and boom stability can be significantly affected. A fine to medium spray quality will give the best chance of hitting small grass weeds, there is only one chance to get it right this spring.”
Mr Nears recommends reversing sprayers into corners. “It’s more time consuming but the best way to achieve good control. When a sprayer sweeps around a corner, the outside of the boom is travelling significantly faster than the inside, resulting in uneven coverage.”
“Patience will pay off this season, take your time and do it properly; slowing down will give the benefits of better coverage, better accuracy and ultimately, better control.”
There will be many jobs competing for the sprayer’s time this spring but Mr Nears argues that grass weed control should be prioritised. “Just 8-12 black-grass plants/m2 can reduce yields by 2-5%. Removing weeds at the earliest opportunity preserves yield potential and prevents them from robbing inputs such as fertilisers.”