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Show U S ft C Extension Service Expert I Describes Alfalfa Veevil Control By George F. Knowlton I Utah State Agricultural College Extension Entomologist The alfalfa weevil has cost Utah hay and alfalfa seed growers many millions of dollars in crop losses over the years. This began in 1904, when the weevil was first found near Salt Lake City. Now this is a pest over most of the west. It recently has caused serious crop injury in some eastern areas of the nation. Insects cause a loss of from $7,000,000 to well over $10,000,000 to Utah crops and livestock each year. The alfalfa weevil annually would cause injury ranging from approximately $300,000 to $1,000,000, if not controlled. Research on alfalfa weevil control, conducted largely by F. V. Lieberman, U. S. Department of Agriculture Entomologist, located at the Utah State Agricultural College, Agricultural Ag-ricultural Experiment Station, has to a large extent made possible pos-sible the elimination of alfalfa weevil crop losses. During the several seasons since the development de-velopment of the new spring stubble-treatment to kill adult weevils, estimated crop savings of k million dollars to nearly one million dollars have been achieved by our Utah farmers. Control the alfalfa weevil In I early spring. Do this by means I of a heptachlor or dieldrin stub-Ible stub-Ible spray, Mr. Litberman and ! other Utah State Agricultural College entomologists advise. This involves applying 4 ounces of actual heptachlor or dieldrin per acre. To ba most beneficial this spray should go on when alfalfa first growth is only to 2 Inches high. This occurs fairly early, we must remember. This early spring treatment is aimed at destroying the overwintering over-wintering alfalfa weevils before the females lav their eggs. Only a few female weevils mature sexually and lay any eggs in the falL This early spring treatment treat-ment makes for better quality and more alfalfa, for larger alfalfa al-falfa seed crops, and makes it unnecessary to have an insecticide insec-ticide residue present on first crop alfalfa when it is cut for hay. Points to Remember To secure most effective and profitable alfalfa weevil control, let's remember a few special points. 1. Whether nlfalfa is grown for hay or seed, the best way to control the alfalfa weevil with an Insecticide is to apply a spray when the first spring growth is to 2 inches long. This usually usual-ly is between Mirch 5 and April 15. 2. Use 4 ounces of heptachlor or 4 ounces of actual dieldrin in at least 6 gallons of water, per acre. 3. This kills most of the adult weevils before they lay many eggs. It thus prevents the development de-velopment of enough larvae to damage the crop later. When first crop alfalfa seed is to be grown, any necessary additional ad-ditional weevil control is provided pro-vided by the application of DDT for control of lygus bugs. This application should be made when the plants are In the early bud stage. The recommended dosages are 1.5 pounds of actual DDT per acre applied as a spray, or at least 20 pounds of l6ro DDT applied as dust. Later Treatment When first-crop hay is raised, some growers may desire to control con-trol the alfalfa weevil by killing kill-ing the larvae after they become be-come abundant, in late May or early June. For maximum benefit, bene-fit, this treatment should be made before most of the plants have started to turn grey. Spray or dust with to 1 ounce of heptachlor or 1 to 2 pounds of actual methoxychlor, 4 ounces of parathion, 2 ounces of aldrin, or 1 to 2 onces of lindane. If parathion para-thion is used, it should be applied ap-plied with power machines only and in strict observance of the directions and warnings of the manufacturer. This control is not considered to equal. In benefits, bene-fits, the spring stubble spray. Wait 3 days bpfore harvest ine heptachlor-treatcd hav. Wait 15 days after treatment before cutting cut-ting hay treated with parathion. aldrin or lindane. Do not feed alfalfa crops Ireaiod with DDT to d.liry animals being milked, to animals being fattened for slaughter or to poultry. When heptachlor. rhlorrlan?. or dieldrin dield-rin is applied ' for early-seasons control of alfalfa wrcvil adults, it is best not to allow dairv animals an-imals being milked to graze on the alfalfa un'il after the first leutting. 1 |