ON SOME LIMITING FACTORS IN THE USE OF SATURATED PETROLEUM OILS AS INSECTICIDES

Owing to the increased use of saturated petroleum oils (i.e., petroleum oils from which all, or nearly all unsaturated hydrocarbons have been removed, usually 98 per cent, or more) as insecticides when applied to foliage-bearing fruit-trees, it has become important to study the effects thus produced on the host plant. The insecticidal efficacy has already been established by de Ong and the two senior authors of this paper (2). It was noted that these oils apparently produce some adverse physiological effects on citrus trees, but this phase of the problem was not especially investigated. The general nature of the deleterious effects accompanying the use of heavy, white-oil sprays has recently been described by Woglum, La Follette and Landon (6) as follows: "The bad effects which have been noted on oranges in some degree since highly refined heavy oil sprays have been used are numerous. They include retarding of blossoming; reduction of blossoming; reduction of crop ; retarding fruit coloration ; interfering with normal sweat room coloring; drop of immature fruit; drop of mature fruit; roughened texture; mummifying of fruit; increasing crystallization; producing insipid flavor;