DANGERS OF DDT

Timaru Herald, Volume CLVIII, Issue 23260, 23 July 1945, Page 6

DANGERS OF DDT

Scientists’ Grave Warning A warning against the use of the powerful new insecticide. DDT, by unqualified people, especially farmers and horticulturists, has been issued by the Agricultural Research Administration of the United States Department of Agriculture. . ■ In a bulletin, the administration states hat it conducted experiments with DDT insecticides during 1943 and 1944 against more than 170 different insects, but it emphasises that a vast amount of further work must be done before such preparations can be safely released for general use. At present, the administration can make no recommendations for the practical use by civilians of DDT in any form on crops or against any insects. Questions still unanswered relate to the best mixtures or solutions to apply, dosages, application schedules, hazards due to residues left on plants, and soils. It is pointed out that results so far obtained are valid only for the conditions prevailing when tile experiments were made, and not otherwise. The new insecticide was found to be outstanding against 30 pests attacking field crops, trees, man and livestock. It was about, equal to other insecticides against 19 more, and had little or no effect against 14 important pests, including the cotton boll weevil. It was most destructive to the codlin moth. Japanese beetle, mosquitoes, bedbugs, house flies, fleas in buildings, and three kinds of lice on man. It is definitely not a panacea for all insect pests. DDT was proved to kill honey bees and other pollinating insects on which many fruit and seed crops depend for fertilisation, also various parasites and predators which help to hold pests in check. The great problem is how to use it. for killing pests without too great destruction of insects beneficial to man. A similar warning has been given by an Australian entomologist. Mr K. C McKeown, of the Queensland Museum. He said recently that the indiscriminate use of DDT could disastrously upset the balance of nature. In an experiment on apple trees affected by codlin moth the moths were destroyed, together with all tlie parasites of the red mite, another menace to apple trees, but the red mite itself was unaffected. Scientific au'dance was clearly essential.