Translocation of aged cyclodiene insecticide residues from soil into forage crops under optimal glasshouse conditions

Abstract

Glasshouse studies were conducted to measure translocation of pesticides by summer and winter forage crop species from soil containing aged residues of heptachlor and, to a lesser extent, dieldrin. Under optimal conditions of temperature and moisture, substantial amounts of heptachlor epoxide, and lesser amounts of heptachlor and γ‐chlordane were translocated to plants from contaminated soil. Residue levels varied with crop species and stage of plant development. In summer crops residues were higher in lucerne>kikuyu>cowpeas. Residues also were found in mature soybeans, i.e. whole tops, pods and beans.

Heptachlor residues in winter crops during early vegetative growth were highest in Saia oats>Berseem clover>Haifa clover>Tetila ryegrass>Schooner barley. In mature crops the order was identical except that Saia oats ranked third rather than first. No dieldrin residues were translocated into the various crop species.

Key words:

• Cyclodiene insecticides
• soil
• translocation
• forage crops