If you are amongst the majority of farmers who have witnessed an upsurge in Ragwort this season, then the coming weeks offer the correct time to introduce control measures, says Nufarm agronomy manager, Brent Gibbon
Ragwort is a biennial weed; seed germinates in spring and by September the plant will have reached the rosette stage. This is the best month to commence control, whilst the plant it still actively growing.
Treating grazing and hay paddocks with a 2,4-D + dicamba (Thrust) combination at the full rate of 3.5 litres/ha before the end of the month can form part of an eradication programme. Where application is impractical for an overall boom spray, use a knapsack sprayer.
Depending on level of this autumn control, then you may wish to follow up with a second application next spring, whilst the plant is still at the rosette stage. Once stem elongation and flowering has been reached, then the opportunity to control Ragwort has been lost.
Remember, Ragwort plants sprayed with herbicide are more palatable and contain higher levels of toxins. Animals should be excluded from treated areas until any Ragwort has completely recovered or died and there is no visible sign of the dead weed, a process that can take up to six weeks. Do not include treated Ragwort in hay or silage crops.
Top, Ragwort treated with Thrust at the ideal growth stage in September 2018; Bottom, the same plant one month later
Finally, please note https://www.gov.uk/government/publications/code-of-practice-on-how-to-prevent-the-spread-of-ragwort
