D.D.T. Residues Studied

Press, Volume CII, Issue 30212, 17 August 1963, Page 7

D.D.T. Residues Studied

Pt view of the similarity erf results obtained with a wide range of plants it appears reasonable to assume that there is no danger of contwninsitton of pastures through absorption of D.D.T. by the roots of plants,” workers ait the Rukuhia soil research station art Hamilton reported to the recent New Zealand weed control conference. Reporting on experiments, they said that the evidence did not preclude the possibility that D.D.T. was absorbed and subsequently broken down in the plant.

If this dad occur the breakdown was relatively rapid. In the case of a new pasture sown on soil treated with D.D.T. the breakdown would take piece before the first grazing by stock. i»ir W. F. Leonard, senior scientific officer with the Department of Agriculture in Christchurch, giving interim results of a study of D.D.T. residues persisting in a number of individual grass species, said it was clear that the investigation of insecticide residues on the basis of individual pasture species was well justified. In a trial at W inohmore irrigation research station, Mr Leonard has been using pure stands of phalaris taberosa, cocksfoot, perennial ryegrass, Yorkshire fog, browntop, Timothy and Chewings fescue. Mr Leonard observed that the feature of results at the cut 68 day* after treatmeat had been the high residue in Yorkshire fog. At 98 days this species still showed the greatest residue, but ait 125 days and where regrowth after the cut ait 98 days was re-cut at this stage, its residue had fallen below that erf cocksfoot.