Pimelea Poisoning - The Plant Enigmas

Pimelea poisoning of cattle has challenged scientists for decades. Most early research was done by animal health specialists and they made critical breakthroughs. Three ephemeral species of Pimelea are reported to be the cause. However, most producers are still unable to devise management strategies to adequately respond to the episodic outbreak of poisonings which seem poorly correlated with abundance ofthe plant in the paddock. Renewed research has looked more closely at the 3 chief suspect plants, P. simplex, P. trichostachya and P. elongata. All 3 species contain significant amounts of the main putative toxin, simplexin, and the toxin is found in all parts of the plant. We have discovered that these plants have different microsite preferences for where they will grow and to what rainfall their seed will respond and germinate. The common factor seems to be open, bare or disturbed ground for germination to occur, but not on extensive scalded claypans. Also none establish well in competition with vigorously growing, tall pasture species nor under a significant tree canopy unless soil moisture is abundant. Each species reacts differently to the post establishment environment. These differences will be documented along with the practical management challenges posed to producers by the multiple but similar looking plants.