Fallopia japonica, Fallopia sachalinensis, Fallopia x bohemica.
Knotweed is a State prohibited weed
State prohibited weeds are the highest category of declared noxious weeds in Victoria. By definition they are either not yet in Victoria, or are here in small numbers, where their eradication is still possible.
All sightings should be reported to Agriculture Victoria immediately by calling 136 186 or emailing email@example.com.
Why is it important to report knotweed sightings to Agriculture Victoria?
Knotweed is native to eastern Asia. It is listed by the World Conservation Union as one of the world's worst invasive species and is now a problem weed in parts of Europe and North America.The invasive root system and strong growth can damage concrete foundations, buildings, roads, paving, retaining walls and architectural sites. It can also reduce the carrying capacity of waterways.
In Victoria, three species of knotweed are declared as State prohibited weeds; Japanese knotweed (Fallopia japonica), giant knotweed (Fallopia sachalinensis) and a hybrid of the two Japanese knotweed (Fallopia x bohemica).
How to identify knotweed
Knotweeds are semi-woody perennials. They flower in summer and most of the foliage will die back over autumn and winter.
Knotweed stems are hollow, bamboo like and can become tough and woody with age.
New stems may be purple-red in colour.
Japanese knotweed leaves have a flat leaf base.
Japanese knotweed has white flowers, clustered in slender branch-like spikes.
Giant knotweed leaves have a heart-shaped leaf base.
Giant knotweed flowers are green-yellow, clustered in loose, branched florescences.
The knotweed hybrid will usually have leaves similar to the Japanese knotweed but can display characteristics of either species.
What should you do if you find knotweed?
If you think you have seen knotweed please contact Agriculture Victoria immediately on 136 186 or send an email to firstname.lastname@example.org.
Please do not attempt to treat or dispose of this weed yourself. Agriculture Victoria will treat, remove and dispose of knotweed safely, at no cost to the land owner.
Knotweeds can form dense, leafy thickets smothering the under story. They can rapidly invade riverbanks and sites subject to disturbance.
Knotweeds die back over winter leaving bare soils open to erosion and young shoots can grow as rapidly as 8 cm a day in favorable conditions.
The vigorous potential of knotweeds is reflected by their ability to regenerate from rhizomes buried up to 1 m deep and to penetrate asphalt 5 cm thick.
In Scotland and other areas of the UK, mortgages have been denied as a result of knotweed infestations, because of the plants ability to grow through concrete structures.
The ability to penetrate concrete and asphalt is due to the plants origins of regeneration after volcanic eruptions, on the high altitude slopes of Japanese volcanoes.