5 of the Most Toxic Weeds on Equine Properties

As an equine property owner in Australia, it's crucial to be aware of the invasive weeds that can pose a threat to your horse's health and the environment.

The source of much of the text here is from NSW Weedwise

They have a terrific database that is easy to search. We would encourage you to identify and learn about weed species in your paddocks that you're unfamiliar with.

Remember, cheap hay is not a bargain if it's full of weeds that are, at worst, toxic to your horses and also potentially invade your pastures with nasties you will be fighting for years.

Here are 5 of the worst weeds you need to watch out for:

1. Paterson's Curse (Salvation Jane)

This notorious weed is highly toxic to horses and can quickly take over pastures if left unchecked.

Individual horses vary in their susceptibility, with some dying after a few weeks grazing Paterson’s curse. Others may graze the weed for successive seasons before signs of poisoning appear. There is usually a gradual loss of condition over four to six weeks followed by listlessness and poor appetite. Some horses show nervous signs such as head pressing, blindness and aimless walking. This is because toxins, normally removed by the liver, build up in the bloodstream and interfere with brain function. Most horses die once the illness is apparent, even after being removed from Paterson’s curse infested pasture

2. Fireweed (Senecio madagascariensis)

Fireweed contains chemicals called pyrrolizidine alkaloids causing liver damage. The damage is irreversible and gets worse the more fireweed an animal eats. Unpigmented skin can become sensitive to sunlight, redden and peel away. Brain damage is common. Symptoms can include: dullness, aimless wandering, an uncoordinated gait, pressing up against fences, gates or trees and possible blindness.

Fireweed is the devil. You can mow and mow and mow to make sure the flowers never go to seed, but you need to collect the clippings because, while most horses will graze around intact fireweed, horses will eat the clippings if you leave them in the paddock, and then be poisoned.

If your neighbour has fireweed you're not going to resolve it no matter how madly you chip it out. If anyone has resolved a fireweed infestation, please get in touch and let us know how.

3. Mother of Millions

Mother of millions, hybrid mother of millions and resurrection plant are all poisonous when ingested. The toxic effects of these plants are due mainly to bufadienolides which cause heart failure. The toxins are present in all parts of the plant however, flowers are five times more poisonous than the leaves and stems.

If livestock have eaten a large amount of plant, they may die suddenly.

If they have eaten smaller amounts over several days, they may develop diarrhoea (sometimes bloody), drool saliva, dribble urine and then die of heart failure. Some affected livestock will recover slowly if small amounts of plant material have been eaten and their hearts are not badly damaged.

4. Cotton Bush

Narrow-leaf cotton bush is a common weed that invades run down or low fertility pastures where it displaces useful species such as clover. Narrow-leaf cotton bush and its close relatives contain cardiac glycosides, which are toxic to humans and livestock. Stock wouldn’t normally eat the plant because its acrid latex makes it extremely unpalatable but it may cause problems as a contaminant of hay or chaff. The main symptom of narrow-leaf cotton bush poisoning is severe gastroenteritis. Narrow-leaf cotton bush also invades riparian areas where it competes with native plants.

5. Deadly Nightshade

These are all over our place. They're easy to pull out, but even touching them is toxic, so wear gloves.

Don't mow over them. Pull them all out, bag them up and dispose of before mowing.

Unripe berries are green, and as they ripen, the berries become black and shiny. This plant causes serious toxic side effects when ingested.

All parts of the plant are toxic, though the root is believed to have the highest concentration of toxins. We find there is often an ants nest underneath. Not sure whether this is common or specific to our place, so be careful of ant bites when you are pulling them out.

Learn how to identify and effectively manage these weeds to protect your horses and maintain a healthy equine environment. Pull them all out by hand, bag them up and burn them! If a new weed appears, get on top of it straight away and avoid a huge headache later.

Weed Management Solutions

A few ways we manage weeds on our property:

Firstly, we always feed hays in the same spot. This way any weeds from hay are isolated to one part of the property.

Secondly, we find a danger time for new weeds is after heavy rain when water runs across the property and brings in seeds from neighbouring properties. This is the time to nip it in the bud.

Third, when we find a new weed cropping up we pull every single one out from the root by-hand, put inside a chaff bag and put it in the bin or burn it. We then revisit the same spot at intervals to make sure a new set of weeds have not germinated.

We have periodically poisoned with glyphosate, but we are not fans of herbicides in general and would discourage you from routinely using Roundup due to its close association with Non-Hodgkin lymphoma for you and the animals (including dogs).