PEST DESTROYERS

Hawera Star, Volume LIV, 20 April 1935, Page 16

PEST DESTROYERS

DERRIS-ROOT POWDER AN INVALUABLE DISCOVERY NO HARMFUL RESIDUE

Scientists arc of opinion that derrisroot powder, a material disco\ ered a ,few years ago by American chemists, may 'ultimately displace arsenieals as insect pest destroyer in fruit and vegetables, states an-Australian farm paper. <; • They aTC also of opinion--.that the toxic properties -of this root may be made up synthetically at a much cheaper rate, and may possibly be used to repel blowflies, codlin moth, and other troublesome pests. • Every year clouds of poisonous dusts and. sprays i are projected pver trees, shrubs'and vegetables in Australia to control insect pests. It stands to reason that much of this poison, the bulk of which consists of arsenic, is absorbed by the fruit or vegetables, and ultimately reaches the stomachs of the consumers.

HARMLESS TO HUMANS With the .idea of overcoming this state of affairs, chemists and entomologists- the world over have experimented with non-arsenicals, and to date the most successful material is derris-root powder, which contains rotenone, a •highly toxic- constituent. So far as is known, derris-TOot powder- leaves no residue behind that will cause any intestinal trouble in- human beings. or animals, and Its use is increasing enormously in Long Island (United States), where countless millions of cabbages and cauliflowers are grown for the New York market. Its value and practicability have been- proven definitely over the last three years-for cabbage moth and aphis control. The early tests showed conclusively that soft-bodied insects, such as thrips, plant lice, and small caterpillars, were easily controlled by derris, and alert vegetable growers were using tons of the material before the experiments being conducted by the American Bureau of Entomology had been properly concluded, and before the scientists could give definite recommendations as to strength and time of application. NEW USES FOUND

Derris-root powder, however, has become recognised- among vegetable growers as a most effective pest exterminator, and almost every month scientists are -discovering new uses for this valuable vegetable dust.

Already experiments have shown that the dust can- be safely used, on asparagus, beans, tomatoes, melons, onions, peas, potatoes, spinach, turnips, cabbages, cauliflowers, broccoli and sprouts. In commercial tests in the United States derris dust applied four times at 15-day intervals during a ten-week period of infestation gave as satisfactory results as five or seven applications at shorter intervals. One user of the dust is of opinion, and this is backed up by officials of the Department of Agriculture, that it may be possible for the control of a number of pests in Australia within a few months.

Rotenone, which is the chief toxic property of derris, is 25 times as poisonous to goldfish as potassium cyanide, yet harmless to birds and animals that have eaten it.

Bumming up derris 1 in- a recent article, the “Industrial and Engineering Chemist,” a prominent American journal, states: “Derris has passed the laboratory stage,' and has proved to be a valuable insecticide for the largestale control of certain insects.”