Saint John's Wort

Saint John’s wort was introduced from Europe as a garden plant and for medicinal purposes in the 19th century; unfortunately because of its aggressive weedy characteristics it readily invades pastures, bushland and grasslands. In South Gippsland it can be seen along railway reserves and some pastures. It has become highly invasive in the east of the state. It has clusters of bright yellow 5 petal flowers, the leaves are small and dotted with oil glands and gives a perforated appearance when held up to the light. Flowers early spring through summer, becoming reddish-brown in late autumn-winter because of mature fruits and old stems. Up to 30000 seeds can be produced from each plant annually and can last for 12 years in the soil. It is spread mainly by wind, machinery slashing and contaminated fodder. Saint John’s wort contains the alkaloid hypericin, which causes photosensitisation in any mammals that ingest it, resulting in blisters on weakly pigmented parts of the skin. Small plants can be removed by hand as long as all plant and rhizomes are removed. Larger infestations can be controlled with appropriate herbicide. In South Gippsland Saint John’s wort is classified noxious, regionally controlled which means it can not be sold or transported and landholders are expected to control and prevent its spread on their land.

Gorse

Classification noxious, regionally controlled. Gorse a weed of national significance was introduced to Australia during the early 1800s as a hedge and ornamental plant. In the Foster and Welshpool area where there is a fair bit of gorse around in the past has been planted and as the gold mine tailings have been moved to different areas seed has been spread infesting further a field. The annual cost of gorse management to agriculture and forest industries across Australia was estimated at 7 million in the year 2000. Living gorse is highly flammable, retains dead vegetation in its canopy, and contains flammable oils. Dense gorse patches increase the risk of wildfire and are a particular hazard near buildings, infrastructure and along fence lines. It invades and dominates bushland, pastures, forest plantations and spreads along roadways. Gorse produces yellow pea type flowers twice a year distributing its seed in the warmer months. A mature bush can have up to 40 thousand seeds in the soil around it per square metre. Seed is viable in the soil for up to 25 years. Gorse can be cut and painted with herbicide but can be difficult because of the sharp spines. Young seedlings are soft and can be pulled out. There are registered chemicals available but to assist the chemical uptake add a penetrant. Infestations normally have to be carefully monitored and retreated on an annual basis.

Water Lettuce

Water lettuce Pistia stratiottes This is a water plant to be on the alert for in South Gippsland. Local landholders often have there dams invaded by various water weeds causing major problems with water quality and choked pipes and troughs. This plant not common as yet in this district has the potential with our changing climate, warming of farm dams and lack of frosts is set to become a serious weed. It declared noxious in the states to the north and west but not yet in Victoria. It is a free floating perennial aquatic herb, which consists of a dense rosette of overlapping leaves on a short stem with long feathery roots, reproducing vegetatively and by seed. The seeds float and can spread through waterways, and the main colony will also spread by the development of daughter plants. Water lettuce is commonly sold in nurseries and through the aquarium trade. Once established it will spread quickly take over the entire surface of freshwater lakes and dams, rivers and canals. The dense plant mass will reduce light penetration, oxygen concentration and pH levels in the water, thus destroying the habitat of fish and is a good shelter for mosquitoes. Control is difficult mainly by manual of mechanical removal. Chemical control is possible but not desirable.

Inkweed

Ink-weed Phytolacca octandra This erect, herbaceous perennial from tropical America used to be a noxious weed in Victoria. It is still considered to be a troublesome weed. It infests bare soil areas and is spread by birds colonising large areas Ink-weed can grow up to 2 metres high and has brittle spreading branches. Red coloured stems which grow from a well developed tap root. It has smooth bright green leaves. Greenish white flowers occur close together on upright tapered spikes between August and November. The fruit are dark purple to black berries which exude a red-purple juice. This plant can turn up in gardens and bushland unnoticed and can dominate large areas inhibiting the growth of more desirable species. Ink-weed can be grubbed out being careful to get as much of the tap root as possible. It will also respond well to being sprayed with an appropriate herbicide. Brush Off can be effective.