Spraying weeds such as docks, thistles, nettles, buttercups and dandelions between now and September will get rid of the problem for this year, and will also keep Westcountry pastures clear next spring too.
That was the advice of Andy Bailey, principal biologist for herbicide manufacturer Dow AgroSciences, who explained: "Weeds have thrived this summer in grassland, reducing output and making fields look unsightly.
"If farmers didn't get a chance to spray in April or May, it's not too late to treat, so long as a broad-spectrum translocated product like Forefront is applied which gets right down into the roots. And because it stays active in the plant for up to 18 months, there shouldn't be any spraying to do next spring either."
Where docks and thistles are flowering, it was best to top them first before applying herbicide, he said.
"Spraying thistles when they are putting up seed-heads will send herbicide up the plant rather than down into the roots where it is needed to achieve thorough and long-term control."
He added: "Better to top them and wait for the re-growth before spraying when docks have reached 25cm high or wide, and thistles are at the rosette stage up to 25cm high. The herbicide will then move down into the roots as long as the plant is not stressed. Use the correct rate. For Forefront this is two litres per hectare, and apply in at least 300 litres per hectare of water for best coverage."
Forefront is not available nationwide but can be purchased in the South West. A prescription-only herbicide, it can only be supplied on the recommendation of a BASIS-registered adviser.
Apply only on fields grazed by cattle or sheep, or after the last cut of silage has been taken. If manure is subsequently generated from grass treated with Forefront, it must stay on the farm of origin and can only be applied to grassland.