Baccharis

Baccharis coridifolia is a significant toxic plant of livestock and one of the most prevalent causes of poisoning in cattle, sheep, water buffalo and horses in Argentina, southern Brazil, and Uruguay.

The plant is contaminated with various species of soil fungi of the genus Myrothecium and Ceratopicnidium baccharidicola which product mycotoxins roridin A and E, miotoxin A, B, C and D, miophytocen A and B, and verrucarol. The plant absorbs these mycotoxins which result in the alteration of cell membrane polarity and enzyme systems, immunotoxicity, and inhibition of protein synthesis. These chemicals combined with macrocyclic trichothecenes present in the plant cause it to be highly toxic.

Once ingested, they bind to the ribosomes at the cellular level which leads to necrosis of the gastrointestinal tract.

All parts of B. coridifolia are toxic, but they are highest when the plant is first sprouting and is maintained in fresh or dry form.

Most poisoning cases occur when ruminants are raised in paddocks without the presence of B. coridifolia are relocated to fields which contain the plant. The risk of toxicity increases when forage availability is scarce, pastures are overcrowded, and grazing animals are thirsty or hungry.