Absorption and Translocation of Insecticides Through the Root Systems of Plants1

Abstract

5 vegetable crops were grown in the greenhouse and field in soil containing concns. of insecticides. Whenever possible observations were made to determine whether the germination, growth and yield of plants were affected. The plants were infested with suitable insect spp. as a qualitative indication of the presence of a toxicant in the plant tissue. Two methods of assaying plant tissue biologically with the aid of Aedes larvae were compared and both found to be sufficiently sensitive to yield a quantitative indication of the presence of a toxicant in the presence of plant tissue. When potatoes were grown in soil containing 10 lbs./acre of the gamma isomer of benzene hexa-chloride, the rate of sprouting and growth was retarded; proportionally greater retardation was observed at higher concns. Aqueous suspensions and benzene extracts of the potato foliage and tubers were highly toxic to Aedes larva. The presence of a toxicant was also indicated when these tubers were infested with larva of the potato tuber worm. Bioassay tests also indicated that a large amt. of toxicant persists in this soil at harvest time. Bioassay tests of potatoes, grown in soil containing 25 lbs. of parathion/acre, indicated the presence of a toxicant. Chemical analyses indicated that the plant above ground, the tubers and the soil at harvest time contained appreciable amts. of parathion.