Rate of Application and Strength of Cryolite Dust Mixtures in Tomato Fruitworm Control

Abstract

Field expts. conducted in southern California from 1938 to 1941 for the control of the tomato fruitworm (Heliothis armigera) with applications of 30, 60, 90, 120 and 150 lb. of 70% cryolite per acre demonstrated that effectiveness is correlated with the dosage. However, the differences in degree of control were not great, and considering costs and the value of the crop saved, the higher dosages in many cases would not be justified. Undiluted cryolite (90%) is more effective than 70% cryolite applied at the same rate of application of dust mixture per acre; but it is approx. of the same effectiveness as 35, 50 and 70% cryolite dusts when the applications are made at the same rate of Na fluoaluminate per acre. The stronger dusts are the most economical to apply, however, because the costs of diluents, mixing, and application are less. 3 applications of 70% cryolite applied at 2-week intervals are not quite so effective but are more economical than 6 applications at weekly intervals.