Experiments on the control of frit fly, Oscinella frit (L.), on late-sown oats with seed dressings and ‘late’ sprays

Abstract

In plot trials with seed dressings on late-sown oats against shoot attack by frit fly, Oscinella frit (L.), chiefly near Cambridge, England, γ BHC, parathion, dieldrin, heptachlor, Rogor and WL 1650 (Telodrin) (1,3,4,5,6,7,8,8-octachloro-3a,4,7,7a-tetrahydro-4,7-niethanophthalan) (dry and wet) reduced the attack but the effect was variable and for the most part not appreciable.In 1952 and from 1956 to 1960, trials were made on the effect of late sprays of various insecticides applied to late-sown oats when symptoms of frit-fly attack were already conspicuous and sometimes severe. An advantage of this type of treatment over preventive sprays is that it ensures that the treatment is applied only where and when necessary. Single sprays of parathion, dieldrin, γ BHC and Rogor prevented or markedly reduced further attack and they were most effective when applied within about 15 days of the beginning of egg-laying and when plants were in the young seedling stage. Compared with the best treatment of two early preventive sprays of DDT there was only a slight reduction in yield. Parathion and to lesser extent γ BHC killed many larvae inside the shoots and probably prevented others from entering the shoots.