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Show Italian Bugs to control Obnoxious Weeds Biological control of two serious weed pests in Utah will receive added emphasis this year. Armed with 8,000 weevil, Rhinocyllus Conicus, that feed on Musk and Scotch Thistle, two Utah State University Extension Specialists are working with County Extension Agents in releasing the weevil on 8 to 10 thistle sites in the state. Louis Jensen, agronomist, and Jay Karren, entomologist, en-tomologist, just returned from a seminar at Boseman, Montana where progress on this form of biological control was discussed. At Boseman, the weevil originally brought in from Italy, have been reared and used in thistle control since 1969. Jensen explained that about three-fourths of the counties in Utah have serious infestations of one or the other or both of these biennial thistles. Some counties have been doing a concentrated job of controlling con-trolling them with chemicals on sites that are accessible for spray equipment. However, there are many areas in the rugged mountain terrain where biological control may be the only practical means of holding down the populations of the thistles and limiting their spread. Jensen said, "You can get an idea of how fasi the Musk Thistle can spread when you realize that one plant may contain 15,000 seeds, and each seed has an attached light feathery growth that can carry it many miles in the wind floating like a parachute. The seeds are also moved by water and other means." The first release of the weevil on Musk Thistle in Utah was made a year ago at a site in Wasatch County up Provo Canyon. Lynn Esplin, ' Iron County Extension Agent, and Earl Smith, Iron County Weed Supervisor released 500 of the weevil on Scotch Thistle in the Kanarraville area near the 1-15 rest stop on June 2. Jensen said, "Authorities who have studied this weevil assure us that it does not feed on any crops grown in the United States, so there is no danger of it becoming a pest. The larvae feed on the immature seeds especially from the earlier flowers. They are effective in achieving about an 80 percent per-cent control on the thistles. The weevil added an important im-portant weapon to the arsenal ar-senal used to control costly weeds." |