Abstract
The use of the overhead-irrigation system established at Colonia Juana Díaz, near Central Cortada, Santa Isabel, P. R., makes possible the application of fertilizers dissolved in water, and of insecticides for the control of soil-insect pests. Experiments were conducted during the crop years 1950 and 1951, using the overhead-irrigation system as a means of applying insecticides, in an attempt to control the sugarcane moth-stalk borer, Diatraea saccharalis (Fabricius). Thirteen different kinds of insecticides, namely: Aldrin, Chlordane, Dieldrin, Ryania, Rhothane (DDD), Benzene hexachloride, CPR Emulsion Concentrate, Gy-phene (Toxaphene), Muriate (Methoxychlor), Kryocide (natural cryolite insecticide), Dilan 25 EM, Heptachlor 2E Emulsion Concentrate, and Dr. Wolf's Insecticide A, were used. Each insecticide was applied at two different concentrations. Thirty-one plots planted with sugarcane, each having an area of 214 acres, were used in the experiment, 20 of them being treated with insecticides and 11 being used as checks. The insecticides were applied at 15-day intervals; there were four sprayings during each season. The experiments were initiated during the fall of 1950 and 1951, respectively, when the sugarcane plants were still small and had just begun to develop the first joints at the base of the stalks. The tables and analyses of the work conducted demonstrated that these insecticides, at least when applied by this method of spraying, were completely ineffective in the control of the insect. In many cases the check plots showed less borer infestation than those treated with insecticides; in others, the insecticide was more effective at low concentration than when used at twice that concentration. The ineffectiveness of the insecticides might be due, in part, to the large amount of water used which reduced the concentration of the chemical so much as to make it valueless in controlling the moth-borer.Downloads
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