Summer is now showing us pretty yellow flowers around the countryside, not Oil Seed Rape I might add but Ragwort.
Ragwort is often a problem on cattle and horse properties as it is can be very poisonous. Sheep are less susceptible to ragwort poisoning but can suffer liver damage, which can eventually lead to death.
The smothering effect of ragwort reduces pasture production and lowers utilisation because cattle avoid grazing close to ragwort plants.
Autumn can still be a good time to control Ragwort with herbicides. This control period can extend to late September or even as late as mid-October depending on the season.
Firstly, weeds which have flowered and are dying off will not be well controlled. Ragwort is still palatable to livestock when dead or dying because of the release of sugars, so although it looks dead it can still become dangerous to livestock.
Ragwort is a biennial so there will be many autumn plants that are small and looking to overwinter, however, under certain conditions plants can be leafy and receptive to herbicide uptake. In most situations a variety of plant types exist within a treatment area. Some will be seedlings, others at the rosette stage and more mature plants can be “multi-crown,” all present at the same time.
No single herbicide treatment provides complete elimination of a ragwort infestation due to successive germinations of the weed and the various growth stages and sizes of plants present. This resilience also means there is little point in using reduced rates of applied herbicide.
Improvements in the performance of hormones herbicides can be made with the addition of certain adjuvants. Always be aware that a good drying period is needed after spraying and never spray if rain is imminent. Clover is generally killed or severely checked. Remember, ‘Clover-friendly’ herbicides are less effective at providing long term control of Ragwort plants.
