Tipping point for the weed from hell

Time to act on Tropical Soda Apple


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The noxious weed Tropical Soda Apple is at a tipping point, say North Coast weed officers, and if we are to eradicate this vigorous feral, which costs South Florida millions every year, then the time to act is now.

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Mirasol Irwin tackles a Tropical Soda Apple in paperbark country, lower Macleay. Fruit is peeled off rather than picked, to prevent seed escape, and buried in bags. The plant is killed with Grazon Extra.

Mirasol Irwin tackles a Tropical Soda Apple in paperbark country, lower Macleay. Fruit is peeled off rather than picked, to prevent seed escape, and buried in bags. The plant is killed with Grazon Extra.

Tropical Soda Apple on the North Coast is invasive to the point where affected landholders can go two ways and both will bring pain.

Bio-security officers from the Macleay to the Tweed told an audience at a Grafton forum last week that the time to eradicate the “Weed from hell” is now. Any later and it will become part of a growing and diverse population of introduced species.

Clarence Valley weed officer Reece Luxton told attendees at a weed forum last week that “We are at the tipping point now, where we can eradicate this weed, or not.  Our goal is for eradication.”  

“However there is a lot of non-compliance and apathy about Tropical Soda Apple. Landholders don’t see it as their problem.”

Troy Irwin regularly harvests Tropical Soda Apple on his lower Macleay pastures and with vigilence and expensive chemicals is managing the invasion. However he says the opportunity to eradicate may have already been lost.

Troy Irwin regularly harvests Tropical Soda Apple on his lower Macleay pastures and with vigilence and expensive chemicals is managing the invasion. However he says the opportunity to eradicate may have already been lost.

A relation of the tomato this particular plant came to Florida from southern Brazil and to Australia in dirty machinery.

Don’t get too cranky with the washdown bloke. It is easy to let this pest go. A sticky goo suspending hundreds of seeds in every fruit goes dry like peanut brittle and doesn’t wash off very easily. The mess sticks easily to fur and feathers, as you would imagine, and remains viable in the intestines of livestock for six days.

The plant is not poisonous to livestock but they don’t go for the spiky leaves. Unfortunately, they adore the ripe fruit, which turns a shade of yellow. So too do feral deer, and pigs and, perhaps most frustrating of all, birds like galahs. 

Each pod produces 400 seeds of which a dozen remain viable after 10 years. Immature fruit, which look like miniature watermelons, also contain some fertile genetics and if they are plucked rather than picked the stem can be left behind, with a sticky film of seedy solution ready to thrive in a sub-tropical environment.

No wonder the scourge is a $13 million problem for southern Florida, where University of Florida professor Dr Brent Sellers described the threat to producers and officers at last week’s weed forum.

The fruit when immature looks like a miniature, globular, watermelon with distinct green and cream patterning. It goes yellow when ripe and the cattle love it, as do deer and galahs.

The fruit when immature looks like a miniature, globular, watermelon with distinct green and cream patterning. It goes yellow when ripe and the cattle love it, as do deer and galahs.

While the problem costs much less in the north of the state, the issue has spread from East Texas to North Carolina.

On the North Coast this plant was first noticed during 2010, although it is believed to have existed here for several years before. Council weed officers concentrated initially on four places: Tallawadjah Creek, Nana Glen, west of Coffs Harbour where it arrived in drought feed; on the Upper Macleay at Lagoon Creek, above Bellbrook; at Wingham abattoir and Grafton saleyards.

Queenslanders first noticed Tropical Soda Apple that same year, at Coominya, north-west of Brisbane. Two years later it appeared at the Casino saleyards and by 2013 it had migrated down the Macleay to Sherwood, north of Kempsey. 

These days it spreads from escarpment to coast.

War of attrition in fight to eradicate feral Tropical Soda Apple

Troy and Mirasol Irwin, Verges Creek on the Lower Macleay inherited seeds from upriver through agistment cattle and local flooding has spread the problem. 

The only eradication method that works is to kill each bush with Grazon Extra. Kempsey Shire Council has helped by supplying chemical. Follow-up spot spraying is essential.

Mr Irwin recommends picking the fruit by grasping its stem between thumb and forefinger before peeling it all off the main plant, otherwise some sticky seeds will be left behind.

Fruit is double bagged and buried. Mr Irwin says burning fails as the seed sprout in the remaining potash and flourish.

“Other people have told me they’ve soaked it in diesel and burnt it and still survived,” he said.

Distinctive immature fruit of the Tropical Soda Apple. Even though these fruit aren't ripe they have some viable seed.

Distinctive immature fruit of the Tropical Soda Apple. Even though these fruit aren't ripe they have some viable seed.

“In our country we’ve been able to pull plants when it’s wet. We’ve had some success. Other times you think it will die but the soda apple resprouts.

“And it is highly likely that the one plant is part of a seed source in an old manure pat and more will come up.”

Quarantining stock is critical, and should be followed anyway under the new biosecurity rules adopted by all graziers.

Cattle take six days to expel the weed seeds from their gut, so weed officers emphasis biosecurity practice to keep the weed under control. Bought-in stock should be quarantined for at least six days. 

For those infected with the weed, there needs to be action on livestock leaving the property by placing them in a clean paddock for a week to ensure they won’t pass seed on to another.

Weed officers say they have long requested that Tropical Soda Apple be declared on vendor declaration forms prior to sale.

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