Rock fern (Cheilanthes) species are naturally occurring, native plants. They are quite common throughout many parts of the north-west. Quite often, grazing animals will consume small amounts of the fern if it is growing in amongst the grass. Unfortunately, there have been the odd cases where excessive amounts have led to stock deaths. And, there have been cases where stock – especially cattle new to an area – will decide to seek out the plants.
One bad example was a case in May 2003 when rock fern species caused the poisoning deaths of up to 30 head of cattle on a property halfway between Bingara and Warialda, NSW. The deaths occurred slowly – and randomly, mysteriously – over a three months’ period. The cause of deaths was eventually confirmed by a local veterinarian when post mortems revealed a buildup of (reddish) fern stalks in the gut. Around the same period, reports were also received of cattle deaths in the Ashford area.
ROCK FERN (Cheilanthes tenuifolia ssp. tenuifolia) and MULGA FERN (Cheilanthes sieberi subsp. sieberi) are very similar in appearance. According to the excellent reference book “Plants of Western New South Wales” by Cunningham, Mulham, Milthorpe & Leigh (published by Inkata Press), the two plants “may be present together in many areas”. [Photos right and below – typical mulga fern plants – Warialda 27 Jun 03).
“Plants of Western New South Wales” states that both species are “not grazed readily by stock but may be utilised in times of extreme food shortage”. While many sheep and cattle deaths have been attributed to rock fern in the past, its close relative mulga fern is the species most likely to have caused the problem.
Selwyn Everist’s “Poisonous Plants of Australia“ (published by Angus & Coote) indicates “mulga fern or rock fern poisonings” occur when the fern is in a dry state and when little other feed is available. In NSW cases are usually reported between January and March while in Queensland cases have occurred more from July to September. In the drought years 1969-70 heavy losses of cattle were experienced.
“Effects on animals are worse if they are driven after eating the fern and if continued the animals usually die. The best option is to remove them from the paddock very slowly if possible. To avoid losses, don’t drive stock, don’t allow access to paddocks with fern or remove them after 10 days grazing and place on other feed for three weeks before returning for another ten days”.
CONTROL METHODS – No herbicides are registered for treatment of rock or mulga fern – both are native species.
- “Plants of Western New South Wales” by Cunningham, Mulham, Milthorpe & Leigh
(published by Inkata Press)
- “Poisonous Plants of Australia” by Selwyn Everist (published by Angus & Coote).
DISCLAIMER: The information contained in this web site is based on knowledge and understanding at the time of writing. However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of North West Weeds or the user’s independent adviser.
Les Tanner 13/07/15