This plant, also called ‘common heliotrope’ is an annual weed that infests the wheat-producing areas of southern Australia. It produces toxic pyrrolizidine alkaloids that damage the liver. In 1993, a serious poisoning outbreak occurred in South Australia when 1000-4000 pigs died over three months because wheat contaminated with potato weed seed was incorporated into diets at about 0.2-1 per cent. Lower levels slowly damage the liver and severely affect growth without obvious signs. Poisoning outbreaks tend to occur every few years when wet summers favour weed growth and delay wheat harvest. Although a safe feeding level has not been established, a maximum of 0.01 per cent might be an interim guideline (about 100 seeds/kg, as 100 seeds = 0.13 g). QASR currently has no standard for this seed because it does not grow in northern Australia.
This table also shows the maximum inclusion rate used in experiments (limited either by toxicity or practicality, in the case of non-toxic seed) and the weight of 100 seeds.
Thornapple (Datura ferox, D. stramonium)
The large seeds of the castor oil plant contain a potent poison called ricin, a toxic protein (toxalbumin). Symptoms of poisoning in pigs resemble botulism except that faeces often contain mucus and are tinged with blood. Depression and paralysis are common. A lethal dose can be as little as two seeds per pig (100 seeds = 22 g). Seeds are more toxic when ground. Under QASR, this plant is prohibited in stock food.
This page describes some weed seeds that are common in Australian grain. It provides the common and scientific names, notes on toxicity and safe feeding levels where possible. The weed seed species are described according to comparative toxicity. Weights of 100 seeds enable the estimation of contamination rates in grain. Tolerable concentrations in pig feeds derived from experimentation are compared with those currently permitted by Queensland’s Agricultural Standards Regulations (QASR) for stock food.
Also known as Salvation Jane, the seeds of this plant contain various pyrrolizidine alkaloids (echimidine, echiumine) in quantities that depend on location and season. The toxins cause liver damage leading to photosensitisation and finally kidney failure. There are no confirmed field cases of poisoning in pigs in Australia. Safe feeding levels have not yet been accurately determined but liver damage is evident with 2 per cent seed in the diet. More than 6 per cent of Paterson’s curse seed in the diet results in a decline in growth rate and feed conversion (100 seeds = 0.37 g). QASR allow 100 seeds/kg (0.04 per cent).
Jimson weed (Datura stramonium, a member of the Belladonna alkyloid family) is a plant growing naturally in West Virginia and has been used as a home remedy since colonial times. Due to its easy availability and strong anticholinergic properties, teens are using Jimson weed as a drug. Plant parts can be brewed as a tea or chewed, and seed pods, commonly known as “pods” or “thorn apples,” can be eaten. Side effects from ingesting jimson weed include tachycardia, dry mouth, dilated pupils, blurred vision, hallucinations, confusion, combative behavior, and difficulty urinating. Severe toxicity has been associated with coma and seizures, although death is rare. Treatment consists of activated charcoal and gastric lavage. Esmolol or other beta-blocker may be indicated to reduce severe sinus tachycardia. Seizures, severe hypertension, severe hallucinations, and life-threatening arrhythmias are indicators for the use of the anticholinesterase inhibitor, Physostigmine. This article reviews the cases of nine teenagers who were treated in hospitals in the Kanawha Valley after ingesting jimson weed. We hope this article will help alert primary care physicians about the abuse of jimson weed and inform health officials about the need to educate teens about the dangers of this plant.