Ragwort is often a problem on cattle and horse properties as it is very poisonous. Sheep are less susceptible to ragwort poisoning but can suffer liver damage, which can eventually lead to death.
The yellow flowered weed favours most well drained fertile soils particularly where the pasture is weak and open. It is a prolific seeder. The seeds may remain viable for over 10 years, and individual plants can produce from 30,000 to 150,000 seeds.
Ragwort incorporated into silage or hay not only retains its toxic properties but also becomes more palatable and, therefore, more dangerous. Ragwort plants, which have been sprayed with a herbicide, show increased sugar levels (making them more palatable) and also higher levels of toxins in their tissues. Stock should not be allowed to graze sprayed ragwort for 2 (and preferably 3) weeks after spraying.
The smothering effect of ragwort reduces pasture production and lowers utilisation because cattle avoid grazing close to ragwort plants.
Ragwort is described as a biennial (i.e. it flowers, seeds and dies between 12-24 months after germinating), but its cycle can be very variable. Plants have been known to flower in less than a year and others may live for over 2 years before flowering. In addition, various forms of damage especially ineffective control methods, can increase the numbers which behave as perennials. These plants tend to be multi-crowned, i.e. having a number of stalks growing from big root masses.
Grubbing or pulling of ragwort plants in the rosette to early flowering stage is ineffectual unless the entire root system is removed. Small root fragments left in the soil will re-grow. Roots of plants pulled at late flowering are less likely to regrow. The flower heads of pulled plants must be burned to prevent the viable seed from spreading.
Mowing any stage of ragwort is not recommended because although it temporarily suppresses flowering and makes for a tidier paddock, it encourages the development of multiple crowns (perennial) ragwort plants.
CONTROL USING HERBICIDES
All products except 2,4-DB (used to control ragwort seedlings only) in some way can damage clovers and with some products, grasses as well.
Apart from large plants in pasture which can be spot treated with grass safe products such as TORDON* Gold or TORDON 2G, the most efficient method of ragwort control is to take a planned approach.
In most situations a variety of seedling, rosettes and multicrown ragwort plants are present at one time in pastures. Two products, TORDON* Gold and Pasture-Kleen* can help provide high yielding pastures within a short time frame. The control programme should begin with the spot spraying of large rosettes and multicrown ragwort plants in March to May, as at this time there is fairly good weather and shorter pastures so plants can be seen more easily. The best products for spot spraying are those that are grass friendly like TORDON Gold or TORDON 2G granules.
To control the remaining rosettes and seedlings, Pasture-Kleen is the herbicide of choice. Application of Pasture-Kleen should be boom sprayed after spot spraying, to ensure all ragwort will be controlled.
The key months for spraying Pasture-Kleen are May/June/July due to ragwort plants being most susceptible.
During this time clover suppression from the Pasture-Kleen is minimal compared to spraying during spring.
TORDON Gold should only be spot sprayed as it is damaging to clover. Full instructions are available on the back of your TORDON Gold container.
A planned approach before ragwort ever reaches the flowering stage (7-8 months before) is the only fully successful method, where all infestations are controlled with little or no pasture damage. As a result there is no compromise to cattle, sheep or deer grazing ensuring they remain healthy.
For more information on Ragwort control or any of the products mentioned in this text, contact your nearest Dow AgroSciences Sales and Technical Representative, your local Farm Merchandise Stockist, or call the Dow AgroSciences free phone: 0800 803 939
*Tordon and Pasture-Kleen are registered trademarks of Dow AgroSciences