By John Bowman, Agriculture Victoria
LARGE quantities of grain and hay have been transported into Gippsland over the last two years to feed livestock, which has increased the risk of some unwanted weeds being brought into the region.
Feeding your stock in either a sacrifice paddock or a stock containment area, so that weed seeds germinate in a designated area rather than germinating all over the farm, can manage the risk of weeds spreading.
Bathurst burr, thistles, wild turnip, stinging nettles and barley grass are among the usual suspects that may have been brought in. Three of the more concerning weed varieties that farmers should be vigilant about are Patterson’s Curse, Heliotrope and Amsinckia.
All three weeds are prolific seeding annuals and can impact stock health if animals graze large quantities of these. They all contain pyrrolizidine alkaloid, a substance that causes long term and irreversible liver damage to grazing livestock.
Patterson’s Curse, a broadleaf weed 30cm to 60cm tall, forms a rosette then develops a main stem and branches, flowers in mid-spring with distinctive purple flowers, grows on well-drained soils and lower rainfall areas but has been known to grow in high rainfall sites.
If eaten in large quantities by pigs, horses, sheep or cattle, Patterson’s Curse can cause liver damage and jaundice (yellowing of the skin).
Amsinckia is an annual broadleaf plant, growing to 50cm and it has small yellow flowers on a long 10cm curved flower head. They produce large quantities of seed in early spring and is reported to have poisoned livestock with similar signs to Patterson’s curse.
Amsinckia is very competitive in pastures and cereal crops and often grows in areas where grain has been trail fed to sheep. This plant is suited to dry or sandy soils in Northern Victoria but has been known to grow in most Victorian soils.
Heliotrope, also an annual broadleaf plant, grows prolifically in Northern Victorian grazing and cropping areas, to a height of 40 cm.
It has small white flowers in late spring and is palatable to sheep. It can contain and accumulate copper, which at high levels is toxic to stock.
Heliotrope can be transported in hay or grain from northern areas and will germinate in the following winter or summer.
It is often seen growing over summer on previous grain growing paddocks or where hay has been fed out in paddocks over the previous season.
All three of these weeds are prolific seed producers and should be controlled with a suitable herbicide registered for their control in the first germination season to prevent establishment. Read the product label carefully and follow the label instructions.
Slashing or cultivation may reduce seed numbers but may not control the weeds, instead encourage them to branch out more seed heads.
Be vigilant and regularly inspect areas of the farm which have had hay or grain fed to stock and remove any unusual or unknown isolated plants.
Sending a photograph to your local agronomist or to Agriculture Victoria is a good avenue for identification.
Unexplained illness or death of livestock should also be promptly investigated by a private veterinary practitioner or reported to Agriculture Victoria animal health staff.
For more information about managing during drought and dry seasonal conditions go to agriculture.vic.gov.au/dryseasons or phone our customer service centre on 136 186.
By John Bowman is a Livestock Extension Officer at Agriculture Victoria, Gippsland.