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ARTICLES >> Property Articles

Decline in Plant Poisonings in Western NSW

Posted by Bestprac on Jul 06 2010

By Greg Curran
Regional Veterinary Officer
NSW Dept Industry & Investment

At a rolling field day from Booligal to Mossgiel in May, the co-author of the renowned book “Plants of Western New South Wales”, Peter Milthorpe spoke about the plants of the area and how the country worked. His experience in western NSW over more than 40 years brought a series of noteworthy conclusions.

Rangelands plant expert Peter Milthorpe and Broken Hill-based Regional Veterinary Officer Greg Curran discussing New Zealand spinach at the Jumping Sandhills at MossgielRangelands plant expert Peter Milthorpe and Broken Hill-based Regional Veterinary Officer Greg Curran discussing New Zealand spinach at the Jumping Sandhills at Mossgiel

 






One was that he’d seen a marked improvement in the condition of the land in that time, with a greater diversity of plant species, and more cover over western NSW. In part, that improvement had been a result of the long wetter period from the mid 1940s to the 1990s, and reduction in rabbits with “myxo” and “calici” viruses, but the RAP (Rangelands Assessment Program) sites across western NSW has shown that people’s management of their pastures has played a major role. So despite now being in a drier period, Western Division pastures have not deteriorated as some might think compared with earlier wetter times.

I was asked to speak on managing plant poisonings by the organisers, Michelle Jefferies of Lachlan CMA and Sally Ware at IIN Hay. Looking back over the records of plant poisonings in western NSW, I’d found that there were far fewer cases and a much lower risk of plant poisonings, than when so much had been learnt about plant toxicities in the 1940s and later decades, which had led to the key poison plant texts by Everist and McBarron. This was surprising, as “Plants of Western NSW” listed 2027 types of plants, and when I’d gone through them, about a third were known or suspected to be poisonous.

In earlier discussions with Peter Milthorpe, I’d asked him if it might be possible that the improvement in biodiversity and ground cover of western pastures had been part of the decline in plant poisonings. He thought it was possible, together with people learning to manage pastures, including the risk of plant poisonings, better over more than a century. Stock have more to eat now, more to choose from, and the chance of any single plant dominating after a rain has fallen. In earlier times, the race between rabbits and stock to find and eat the best feed had often given the least palatable and the more toxic plants a better chance of surviving and seeding than more palatable, more nutritious and safer species. The balance between the quantities of poison plants and safer plants appears to have shifted, not simply from good luck and the right rains, but by applying good management of stock and rabbits.

The day brought a couple of other observations. Jim and Alison Crossley of Toms Lake mentioned finding that their Dorpers had done well on rundown country they’d bought 7 years ago, which had been dominated by bushy groundsel (Senecio cunninghamii), a poisonous plant that had claimed cattle and made life hard for Merinos. They’d not had any losses in their Dorpers from this plant’s poisonous alkaloids as I’d expected. The late Ken Jubb, Hay RLP Board’s vet, had checked livers from the Crossley’s Dorpers, and did not find evidence of damage from these alkaloids. Jim has got to the point where he was calling this resilient and deep-rooted perennial “Booligal lucerne”, at least for his Dorpers. He’s building this plant into his grazing management, and will hold it over to provide green summer feed. I speculated that perhaps their African heritage of thousands of years of selection for survival on herbages that contain alkaloids might be part of why the Dorpers had done well on a Senecio. An example of people finding opportunity in what others thought a problem. It reminded me that people have used Dorpers’ strong preference for fireweed, another Senecio, to control this weed, apparently without being poisoned.

David Butcher, from near Mossgiel, followed this by commenting on how stock did on Wards weed (Carrichtera annua), a plant that had invaded large areas of western NSW over the last 20 years. A member of the Brassica family (like turnips, radish, mustard, rape and cabbages), Wards weed is generally a plus, giving green pastures shortly after rains, and its tough stems and roots holding the country together. I’d seen occasions where stock had died on Wards weed, with symptoms similar to those seen with other members of the Brassica family. Again, by applying good management and properly assessing risks, people have been able to benefit from a plant that can be a problem.

Broken Hill-based Regional Veterinary Officer Greg Curran (right) discussing the plant Bushy Groundsel at a site near Booligal.  This plant contains high level of alkaloids which causes liver damage and death in cattle.  It however, can be readily grazed by sheep.  Also in the photo is rangeland plant expert Peter Milthorpe (left) and local property owner Jim Crossley who considers the Groundsel useful feed for his sheep.

Broken Hill-based Regional Veterinary Officer Greg Curran (right) discussing the plant Bushy Groundsel at a site near Booligal. This plant contains high level of alkaloids which causes liver damage and death in cattle. It however, can be readily grazed by sheep. Also in the photo is rangeland plant expert Peter Milthorpe (left) and local property owner Jim Crossley who considers the Groundsel useful feed for his sheep.

Last changed: Feb 07 2012

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