Portal de Periódicos da CAPES

The Medusahead Problem in Idaho

1961; Cambridge University Press; Volume: 9; Issue: 1 Linguagem: Inglês

10.2307/4040395

2326-1315

P. J. Torell, L. C. Erickson, R. H. Haas,

Plant Parasitism and Resistance

N EDUSAHEAD, Elymus caput-medusae L., is currently the worst AlV range weed in Idaho. It has gained this distinction because of its rapid migration, its vigorous competitive nature, and its extremely low forage value. In the absence of effective control measures, the medusahead problem is becoming more acute each year. The threat that the weed poses to Idaho's livestock industry is sufficient to merit grave concern. According to Abrams (1) medusahead is native to Europe. The same author points out that medusahead was first described by Linnaeus, in 1753. Thus, while the species is one of the earliest to be recorded by botanical science, it is a relatively recent introduction to the United States. Furbush (2) provides the earliest reference to medusahead in the United States by his account of a collection of the species made near Roseburg, Oregon, in 1887. St. John (9) noted another early collection of medusahead by G. R. Vasey near Steptoe, Washington, in 1901. The earliest authenticated specimen of medusahead in the University of Idaho Herbarium was collected in Owyhee County in 1946, by Ray J. Davis. However, ranchers in southwestern Idaho maintain that the weed was noticed in Gem County during the 1930 decade. Although the origin of medusahead in Idaho is obscure, the species has demonstrated that it is capable of rapid migration. In 1952, Sharp and Tisdale5 referred to a weed survey that indicated there were at least 30,000 acres of medusahead in Idaho. In 1955, Hironaka et al. (3) estimated that Idaho's medusahead infestation amounted to 150,000 acres. In 1959, the Bureau of Land Management6 reported 700,000 acres of the weed in southwestern Idaho. Idaho's largest medusahead infestation occurs in the southwestern part of the state (Figure 1). The recent survey by the Bureau of Land Management shows that the major portion of the infested area is in Gem, Payette, and Washington Counties. Smaller but