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Fighting Triffids

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Peter Shooter continues to lead his teams of FIDO volunteers in their never-ending war against the very aggressive and invasive African subspecies of Abrus prectorius. The native Abrus prectorius, which does not naturally occur south of Gladstone, would never be termed aggressive in its natural range. As Peter prepares for another round of battle against this die-hard opponent in May (funded by BMRG), comparisons are being made to trying to eliminate triffids! However, Peter and his teams believe that, albeit slowly, they are beginning to gain the upper hand.

Abrus infestation

A shot of a heavily infested area on Education Department land at Happy Valley in March before treatment. This is all regrowth since it was sprayed in November 2015, possibly all new seedlings. All the growth was on the ground or on small shrubs to 1 metre, with none up in the canopy. Canopy infestation was all destroyed in November.

Luckily, Abrus exists only in Happy Valley and its immediate surrounds.  Another factor in the favour of Peter and his team is that all of the evidence suggests that the plant’s spread is constrained by its manner of dispersion: in the foot pads of dingoes. There is no evidence to suggest that birds disperse the poisonous bright red and black seeds that give the plant its colloquial name of Crab’s Eye. The Abrus thus follows very closely the roads in and out of Happy Valley and, with the exception of an area north of Happy Valley that is a known dingo lair area, is not being carried too far from the main Happy Valley infestation.

As a result of trials, it has been found that manual removal of Abrus (even cut and paint) is almost impossible unless treatment areas are revisited at least weekly. Therefore, the most effective way to control Abrus is by chemical spraying with glyphosate. Peter’s teams have to comprise some very fit warriors, to lug 15 kg backpack sprays through heavy bush and up steep slopes; however, they do it with good grace to protect K’Gari’s natural integrity, oftentimes coming back for more.

A major problem in controlling Abrus is that it is a prodigious seeder and the germination rate of the seeds is alarming. Peter’s battle plan is:

  1. to maintain regular spraying to kill existing Abrus before it seeds
  2. to continually go over previously treated areas to kill off any seedlings from seed dropped previously, before they can seed again
  3. to make it a priority to eliminate all Abrus outside the dingo fence to stop the spread of Abrus beyond Happy Valley, before closing in on the last of the enemy inside the perimeter.

Knowing how long the seed remains viable is critical.  For this reason, one of Peter’s fellow volunteers, Peter Dorney, a Sunshine Coast nurseryman, in March set up scientific germination trials to answer this vital question.  This prompted Su Dawson to find some seeds that she had put away in 2013 to see if they would germinate.   Beating the triffid-like Abrus will require strength, enthusiasm and a bit of science.

Side activities:  The team did a bit more than just spray Abrus in March.  Apart from their ‘work’, they would walk the beach and collect litter—lots of litter, and some was huge.  Peter Shooter reported:

 Every day in his spare time Geoff walked the beaches collecting man-made ‘flotsam and jetsom’ and depositing it in piles for later collection.  On the last day of our trip, we took the trailer to Eurong and swept the beach from Eurong to Eli Creek.  Many large items including pallets, drums, rope, poly pipe, oyster racks and more were removed. Geoff’s piles contained all the predicted items—thongs, bottles and plastic bags, to name a few.   The most spectacular, and by far the largest, piece collected was a bamboo raft, half buried in sand, high on the beach. We finally got it out with the help of a tow from the 4WD.  This raft is very well made with skilful bamboo joinery and lashing.

Raft

FIDO volunteers with beach rubbish for the tip. The main item is a bamboo raft, sadly upside down. From left: Pete Dorney, Geoff Welsh, Peter Shooter and Charlie Charldsworth. Photo courtesy of Chris Brietenbach

John Sinclair (AO), FIDO


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