Eliminate cotton bush | In the Green Room

The Peel Harvey Biosecurity Group is making an effort to eliminate cotton bush – a prevalent toxic weed in the south-west of Western Australia – from the Peel region.

The bush, which originated in South Africa and was originally introduced as a garden plant, has come to thrive in the nutrient-depleted paddocks and river banks of the Peel Harvey estuary and surrounding areas.

The plant is known as cotton bush because of the fluff that emerges from the seed pods when they open.

This fluff gives the plant a highly effective method of seed distribution: they help the plant to spread far and wide via the power of wind.

Each pod contains about 100 seeds, which makes the cotton bush a very successful plant in terms of reproduction, but particularly nasty as a weed.

That’s why it’s important to ‘nip it in the bud’ if you find any on your property.

It’s best to remove the cotton bush before it can set seed, and to collect any pods that have already formed in a plastic bag to avoid any further seed spreading.

The seed pods themselves are described by the WA agriculture department as “puffy, swan-shaped structures up to 6cm long, and covered in soft spines”. They can also be rounder in shape.

The two-meter high shrub has small white flowers from October to April, which cluster in drooping sprays.

When it’s young, cotton bush has only a shallow root system, so it’s relatively easy to pull by hand.

Ensure you wear gloves and appropriate clothing to avoid contact with the poisonous milky sap that will irritate your skin.

When pulling the plants, make sure you’ve got the roots and all: cotton bush is especially prevalent because it can re-sprout from the crown or roots.

If the bush has already set seed, cover it with a large plastic bag to stop any seeds blowing away.

If you need to get rid of a larger thicket of cotton bush, you may have to resort to either poisoning, slashing and burn-offs.

Burn-offs are particularly effective as it also damages any seeds that may have settled in the soil. 

Also be wary of mulches, feeds and soils that may contain seeds: even if it’s cheap, it’s going to cost you more in the long run if you get a cotton bush infestation.

Controlling cotton bush may seem like a strenuous task in the short term, but if left to reproduce, these plants can become a problem not just on your own property but for neighbours and nearby nature reserves, too.

The plant becomes a real problem if it gets into feed, because of its toxicity, and in a natural environment can strangle out native plants needed by wildlife for habitat.

For more detail on cotton bush and biosecurity in the region, visit peelharveybiosecurity.info

Do you have a gardening question for Jess, our resident plant enthusiast? Send your queries to jess.cockerill@fairfaxmedia.com.au or call 9550 2409.