|Halogeton (Halogeton glomeratus)|
Halogeton, a fast-growing annual plant of the Western States, frequently causes poisoning in sheep. Cattle may be also be poisoned. Livestock readily graze mature, dried halogeton and most losses occur when hungry animals are allowed to graze in heavy stands of halogeton. It grows from 0.1 to 1 m tall depending on the moisture available during the growing season. Each plant generally has five main stems that come directly from the base of the plant. Young plants have round, fleshy leaves that grow in little bunches along the stem. It has a characteristic small hair about one mm long on the end of each leaf. During drought the stems develop a reddish tinge.
The toxic substance in halogeton is sodium oxalate, which is contained in leaves and other above-ground parts. Halogeton is dangerous at all times. It becomes more toxic as the growing season advances, reaching a peak of toxicity at maturity. Losses occur from dried plant consumed during the fall, winter, and early spring.
Where and When It Grows
How It Affects Livestock
Signs and Lesions of Poisoning
How to Reduce Losses
Do not introduce livestock into areas heavily infested with halogeton unless it can be done slowly to allow time for adaptation to the toxin. This can be accomplished by grazing plants such as shadscale or light stands of halogeton. Livestock should not be allowed to become hungry or thirsty while grazing in areas infested with halogeton. Death in livestock occurs when an animal eats a large amount of halogeton in a short period of time. Animals unloaded in halogeton-infested areas after train or truck shipment may benefit from supplemental feeding before grazing in the halogeton-infested areas. As most grounds around water tanks are infested with halogeton and many livestock graze indiscriminately after watering, livestock deaths often occurs after thirsty animals are watered.
Treatments for halogeton poisoning have not been definitely proven to be effective. It has been suggested that oral dicalcium phosphate may reduce oxalate bioavailability by forming insoluble calcium oxalates (3:1 salt to dicalcium phosphate or 5% calcium phosphate in alfalfa pellets). Treatment of hypocalcemia with intravenous calcium gluconate will correct the hypocalcemia, but does not reverse the clinical signs or course of the disease.
Because each plant produces vast numbers of seed, some of which may survive for 10 years or more in soil, it is not practical to eradicate any population that has been in existence for 2 years or more. Plants can be held in control by proper use of herbicides, and very small infestations can be eradicated if treated early. Research results indicate that several herbicides are effective for halogeton control. The low volatile ester of 2,4-D will kill about 97 to 98 percent of the plants when applied in late May or early June, but is not selective. Such treatments deplete other vegetation resulting in further invasion by halogeton (from seed in the soil) or other pioneer invaders, such as Russian thistle and rabbitbrush. Applications of 1 kg per acre of telbuthiuron as late as August will kill the halogeton and prevent reinvasion for 3 to 5 years. Apply 2,4-D with extreme care to protect broadleaf perennials. Use the herbicide only to treat small infestations of halogeton. Repeated treatments are necessary for control. Seeding infested areas with crested wheatgrass has been used extensively to crowd out halogeton and improve ranges.
Herbicide control of established stands on saline soils and low precipitation is not recommended. Follow recommended precautions when applying and handling herbicides.