Fireweed Intoxication in Horses
& Other Species

Link: Fireweed Intoxication in Horses & Other Species

What is Fire weed?

This seemingly pretty plant is a weed that is toxic. This weed is found growing in paddocks, along roadsides and in drought ridden pastures. The fire weed plant is easily recognisable with its mid - green leaves on branched stems but its main characteristic is its yellow daisy like flowers, Each fireweed plant can produce up to 30,000 seeds per year. The seeds are attached to a pappus made up of silky white feathery hairs and are easily dispersed by wind, wandering animals and vehicles.

Why and How is it toxic?

Livestock will avoid consumption of the plant or flowers when other feed is available, but in heavily infested pastures especially with young plants it cannot be avoided. The fire weed in-flower is the most toxic. When ingested it can be toxic to the liver and neurological system eventually leading to death. People should also be aware that fireweed is also toxic to humans if ingested and be sure to wear gloves when removing this plant.

What are the signs of intoxication?

Generally horses and other livestock will have to consume a small amount over a long period of time or a large amount over a short period of time to have an effect. Some of the symptoms can be diarrhoea, temperature, aimless wandering, loss of condition, weight loss or no weight gain and no interest in eating or drinking. They may also show abnormal behaviour such as head pressing, convulsions or tremors and change in temperament. Although fire weed is toxic most cattle and horses will avoid consumption as long as the feed is available.

Fireweed

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Fireweed

Native to southern Africa, fireweed is a daisy-like herb. Fireweed was first recorded in Australia in the Hunter Valley in 1918. It is thought to have arrived in the ballast of ships trading between Australia and Europe via Cape Town. Fireweed spread slowly at first, but, in the past 30 years, has rapidly increased its range, most likely aided by modern transport and rural practices.

Fireweed competes with pasture and is toxic to livestock. It is found along the entire New South Wales coast and scattered across various regions of Queensland.

Fireweed can easily be mistaken for closely related, native Senecio species, particularly Senecio pinnatifolius and Senecio brigalowensis. Senecio brigalowensis is increasingly abundant and weedy in Central Queensland from Roma to Rockhampton, and also causes cattle poisoning.

You must manage the impacts of Fireweed on your land.

You must not give away, sell or release Fireweed into the environment.

Scientific name

Senecio madagascariensis
Similar species
Native Senecio spp.

Description

Annual or short-lived perennial herb.

Plant varies greatly in size and shape depending on conditions.

In dry harsh conditions, may be less than 20cm tall with narrow leaves, no branching and few flowers.

In ideal conditions, grows up to 50cm tall with multiple branches, long, wide leaves (6cm x 2cm) and about 100 flowers.

Leaves are generally 2–6cm long, alternate, dark green, with serrated margins.

Flowers are bright yellow, daisy-like, with diameter of about 2cm, producing up to 100 seeds each.

Each seed is 2–3mm long and cylindrical in shape, with rows of very fine short hairs and silky pappus (parachute).

Taproot is shallow-branched with many fibrous roots.

Habitat

Seeds germinate in mild, warm conditions with light and moisture. Light infestations can produce 1 million seeds per hectare.

Distribution

Visit Weeds Australia and click on the distribution tab to access the distribution map.

Life cycle

Seedlings appear March–June, growing quickly to produce first flowers in 6–10 weeks.

Begins to dieback in spring.

Dry summer followed by autumn or winter rains leads to heavy infestations.

Affected animals

Livestock

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