Plants Toxic to Horses: Hoary Alyssum found in Hay, Pasture

Links to Hoary Alyssum photos and information

Hoary Alyssum: Toxicity to Horses, Forage Quality, and Control

Discusses the possible toxicity of the weed hoary alyssum to horses, and clinical signs of toxicity. Includes information on forage quality and palatability of hoary alyssum and its biology and control. For those who own or keep horses, and for hay producers.

Hoary Allyssum

Hoary Alyssum / Berteroa incana / Tall Whitetop
Native to southeastern Europe and southwestern Asia
Noxious biennial (rarely perennial)
Annual to short-lived perennial
In the Mustard Family
Grows to 0.7 metres tall

Hoary Alyssum in Hay, Pasture and Forage

Hoary alyssum (Figures 1, 2 and 3) is a weed common to Minnesota, the surrounding states, and Canada. It is particularly adapted to dry conditions such as occur on sandy or gravely soils. Hoary alyssum is a member of the mustard family and is perennial in its growth habit. Hoary alyssum tends to increase in forages following drought or The grey-green leaf of hoary alyssum.winterkill, regardless of the soil type of the field.

Hoary Alyssum in Pasture and Hay Fields in Southwest Michigan

Farmers and horse owners should be on the lookout for hoary alyssum, a weed species that has been found in a few hay fields in southwest Michigan which can be poisonous to horses. University of Minnesota Researchers reported that the ingestion of hay that contains a high level of hoary alyssum can cause horses to experience depression and cause a swelling of the lower legs. Fever and short term diarrhea also can accompany ingestion of the plant. Clinical signs normally subside within 2-4 days after the horses are removed from the alyssum source. In severe cases, foundering with stiffness in joints has been observed.

Hoary Alyssum - Stevens County Noxious Weed Control Board

Key identifying traits
* Flowers are white with 4 petals, deeply divided
* Usually only branched at the top of the plant
* Leaves are alternate, blades are simple
* Fruit is oblong, with two compartments containing 2 to 6 seeds
* Seeds grow close to stem, are round to oblong, narrowly winged, grayish-brown and rough

Ontario Weeds: Hoary alyssum

It is distinguished from other mustards with rounded seedpods by its stalkless, non-clasping stem leaves with smooth (entire) margins, the dense star-shaped hairs that give the whole plant a hoary appearance, and the broad septum (membranous partition) in the oval, hoary seedpods which are held erect and very close to the stem.

Toxic Weed Hoary Alyssum Found in Drought-Affected Pastures

News and veterinarian-approved articles on equine health care from The Horse magazine.
The 2007 growing season's drought conditions are causing challenges for anyone who handles plants or animals. Horse owners are no exception, and to a list of concerns including a shortage of hay and lack of pasture growth they need to add awareness of hoary alyssum, a weed that is poisonous to horses. Hoary alyssum is found across the northeastern and north central United States and Canada.

Beware Of Hoary Alyssum In Horse Hay | toxic weeds in horse hay

Georgia horse owners are urged to check alfalfa hay for a toxic weed and to consult with their veterinarians if their animals get sick. Tommy Irvin, the state's ag commissioner, says the weed has been found in some alfalfa from the Upper Midwest.