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Show EARLY SPRING IS TIME TO CONTROL ALFALFA WEEVIL By GEORGE F. KNOWLTON Extension Entomologist Utah State University Alfalfa weevil control time will be here "before we know it." Too many alfalfa growers spray their fields "on the late side." Early spraying is the time which gives very best control. con-trol. It costs no more to time the spray right The benefits of this useful precaution are higher quality and better yields of alfalfa. WHAT TO USE: Insecticides recommended for stubble spraying are heptachlor and dieldrin. Pay your money and take your choice. Rarely has a failure occurred when four ounces of actual chemical, dieldrin diel-drin or heptachlor, was applied before the earliest alfalfa spring growth had reached 1 inch in height. One gallon of heptachlor 25 emulsifiable concentrate contains con-tains 2 pounds of actual heptachlor hep-tachlor toxic chemical. Thus, one gallon of this is just right to treat 8 acres of alfalfa in early spring, for either a forage for-age or seed alfalfa crop. Don't skimp and reduce control effectiveness. ef-fectiveness. Dieldrin emulsified concentrate concen-trate comes at an 18 strength. One gallon of this dieldrin concentration con-centration will treat 6 acres for adult alfalfa weevil control. If army cutworms also are found to be numerous, spray the fields with dieldrin, but at a strength of 6 ounces per acre. At this dosage, the combined com-bined treatment should use one gallon of dieldrin concentrate for every four acres treated. WHEN TO SPRAY: Spray alfalfa fields early in spring. , It is not necessary that the fields- show greening. Plan to treat before earliest growth ' is V2-inch high, on close examination. examina-tion. Don't wait for a warm, sunny day. Just don't spray when too muddy for the equipment equip-ment to operate, or if the wind is so strong as to prevent spray from uniformly covering cover-ing the plants and soil. A good rain or snowstorm after early weevil treatment does not reduce the control effectiveness.' ef-fectiveness.' In fact we havo Make a close-up examination. Alfalfa showing green from the highway already is past the recommended time to spray. Check soil in alfalfa crowns for the presence of army cutworms; cut-worms; if cutworms also threaten, threat-en, spray promptly with dieldrin diel-drin at 1 gallon of emulsion to each four acres. Cutworms often prevent hay crop from growing normally. some evidence that extra moisture mois-ture washes the chemical down in the soil, making greater contact con-tact with the" adult beetles overwintering ov-erwintering in the crowns of the plants, thus giving even better control. Our strategy is to kill the overwintered adult female beetles beet-les before they lay their eggs. Every egg laid before control is applied means a worm may be feeding on the plant in later spring. The earlier the spray, the better the kill, and the better the hay quality at harvest time. Don't spray alfalfa after it has grown to be several inches high. This is particularly important im-portant if the alfalfa is a forage for-age crop. We must not have a residue of dieldrin, aldrin, heptachlor, DDT, chlordane or related chlordinated hydrocarbon hydrocar-bon pesticides on any hay which might be fed to dairy cows, poultry, or animals being finished for slaughter. These chemical residues have a way of appearing in the milk and in the fatty tissues of animals which feed upon such forage. This residue problem we can and must avoid. We get better bet-ter control when we spray earlier in the spring. A FEW "DO'S" . Put your spray in A-l oper-I oper-I ating condition right away. Order the chemical of your choice and have it on hand early. Spray at the earliest sign of alfalfa greening in your field. |