Wednesday, November 01, 2017

WoNS (Weeds of National Significance)

A weed is any plant that requires some form of action to reduce its effect on the economy, the environment as well as human health and amenity.
There are thirty two WoNS on the Australian government's list. Their inclusion is based on their invasiveness, potential for spread and environmental as well as social and economic impacts.
Many plants introduced into Australia in the last 230 years ie since European settlement, are now weeds.
But a native species that colonizes and persists in an ecosystem in which it did not previously exist can also fall into this category. Snakevine (Hibbertia scandens) is a prime example on our property. It grows prolifically here and can cover large areas very quickly taking over productive pasture.

It is sold in local nurseries as a garden plant which I find a little bemusing.
Another is native tussock which I have written about a few times.
Obviously not all of the thirty two WoNS affect all regions of Australia but here are the ones (and their origin) that are listed for our part of the continent.
*Asparagus Fern (Asparagus aethiopicus) - South Africa
Bitou Bush (Chrysanthemoides monilifera subsp. rotundata) - South Africa
English Broom (Cytisus scoparius) -
Water Hyacinth (Eichhornia crassipes) -
South America
*Lantana (Lantana camara) - Central and South America
Gorse (Ulex europaeus) - Western Europe and UK
*Fireweed (Senecio madagascariensis) -
Madagascar and southern Africa
*Blackberry (Rubus fruticosus) -
Prickly Pear (Opuntia spp) - North and South America
*Serrated Tussock (Nassella trichotoma) - South America
Chilean Needle Grass (Nassella neesiana) - South America
African Boxthorn (Lycium ferocissimum) - South Africa
The ones that we are most concerned with here are noted with a * with three being a particular problem.

              Blackberry                 Fireweed                  Giant Parramatta Grass

States and local councils also have weed lists which contain many more than thirty two. Our state list has over 300.
We got a visit from the local council 'weed lady' the other day who inspected our property for any 'nasties'.
She was looking for those on our *list plus Giant Parramatta Grass (Sporobolus fertilis)
We are continually battling Blackberry and have had one small out break of Fireweed many years ago which we got under control eventually completely eliminating it.
Our neighbours have had Giant Parramatta Grass on their properties and it also grows on many public road verges in the vicinity. I have never seen any here.
However nothing reportable was found during the inspection which is good. I really try to keep things under control weed wise.
She however did notice some wild tobacco (Solanum mauritianum) seedlings which are poisonous to cattle.

This is a long-lived (ie. perennial) shrub or small branching tree usually growing 1.5-4 m tall, but capable of reaching up to 10 m in height. I have been aware of this problem and spray them off when doing other weed remedial work.
So I will be on the lookout for this one when recommencing my battle with the tussock and bracken next autumn.

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