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Home>Plant Species>Weed Species>Halogeton

Drawing of halogeton Halogeton
Halogeton glomeratus

question markDid you know?

Halogeton is poisonous to sheep! 


How did halogeton get here?

This nasty weed was once theorized to have been introduced by Russian spy planes as a biological weapon during the Cold War. While halogeton is native to Russia, as well as China, its more likely introduction was through accidental seed contamination rather than a covert operation by the Soviet Union. The first herbarium collection was in 1934 in Nevada. Since its arrival, halogeton has rapidly invaded millions of acres in the western United States.

Close-up of halogeton leaves and stemWhat are its characteristics?
This annual forb ranges in height from 3 to 18 inches. Its stems branch at the base, spreading out at first then growing upward. Leaves are small and fleshy, ending abruptly with a needle-like spine. Plants are green in the spring and early summer, then turn red or yellow by late summer. Flowers may be hard to recognize, yet produce 75 seeds per inch along the stem. Seeds are polymorphic, meaning there are two types with different germination requirements.

Although halogeton can occur on many soil types, invaded sites are usually saline. Halogeton is not extremely competitive, but it quickly invades disturbed or over-grazed lands. Palatability is low and the plant produces toxic oxalates that are especially poisonous to sheep. Heavy sheep losses through halogeton poisoning have occurred on ranges in Idaho, Nevada, and Utah.

Why is halogeton a problem in the Great Basin?
Besides being poisonous, halogeton makes it is difficult to establish desirable plants. It can change the soil by pumping salt to the surface, slowing moisture infiltration and increasing evaporation. Local spread of halogeton is primarily by the wind as plants break off when dry and tumble with the wind. Dust-devils can transport dry stems with seeds up to 2 miles. Halogeton seeds can germinate after passing through the digestive tracts of sheep and rabbits.

How can we fight this weed?Picture of halogeton plant next to a man's foot
Sheep can safely eat halogeton after some of the oxalates are removed by rain or snow. Sheep can adapt to eat more halogeton if fed to them in gradually increasing amounts.

The best defense against halogeton is a vigorous stand of perennial plants. Introduced perennials, such as forage kochia and crested wheatgrass have been successful at decreasing halogeton cover. A variety of crested wheatgrass, called Hycrest, tolerates salty soils where halogeton is most common. Biological control with insects has not been successful.

Images:
-Drawing: Public use.
-Leaves: Intermountain Herbarium.
-Plant: Steve Schoenig (2001) CDFA

Text references:
-Pavek, Diane S. 1992. Halogeton glomeratus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: (http://www.fs.fed.us/database/feis/, 26 September 2006).
-USDA, NRCS. 2006. The PLANTS Database (http://plants.usda.gov, 26 September 2006). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
-Whitson, T. D., et.al. 2000. Weeds of the West., 9th ed. Western Society of Weed Science, Newark, CA.