USING INSECTICIDES

Press, Volume CV, Issue 31018, 25 March 1966, Page 6

USING INSECTICIDES

Plants, whether ornamental or of economic importance, usually require a certain amount of cultural attention if results are to come up to expectations. Many of them are susceptible to the ravages of insect pests, some much more so than others, and if protection is not afforded them they will rapidly succumb and possibly die from the injuries thus received.

In consequence it becomes most necessary to give protection usually in the form of an insecticide, which may be sold under a variety of proprietary names, although their basic ingredient is the same.

The chemicals used to combat insect pest depredations of plant life act in a number of different ways and may kill by contact or Indirectly through consumption of the treated insect’s food. They are classified as follows, a means by which one can understand the use and function of a particular material that it is intended to use. Selection is actually dependant on the type of mouth parts, and therefore the mode of eating, of the insect. Stomach insecticides such as aldrin, dieldrin, endrin and arsenate of lead kill when the insect comes into contact by chewing a treated surface. All plant surface areas must be treated to give desired protection.

Contact insecticides, of which D.D.T., D.D.D., pyrethrum, and chlordane are examples, on the other hand kill the insect when it crosses the treated surface. Successful application, therefore, requires complete plant coverage once again. Systemic insecticides include phosphamidon demeton, and a recently introduced one, menazon. This form of chemical is used to destroy insects which do not chew or eat parts of the plant but suck the sap or plant juices. It is not necessary to obtain complete coverage when applying systemics as they are absorbed by the treated surfaces and translated throughout the plant. Fumigants are the last group of insecticides and include methyl bromide, azobenzene, lindane, chloropicrin and dichloroproprene. These materials, in the form of smokes and gases, achieve their purpose by poisoning the atmosphere, thus killing the insects when they breathe.

Many materials are very poisonous and under the

Poisons Act the use of certain insecticides implies a specified minimum waiting period before a particular treated crop can be harvested. For instance, if D.D.D. is used it. is generally required that three weeks must eiaipse before use, whereas carbryltreated crops may be harvested the next day. Further, many substances are either no longer available to the home gardener, such as nicotine sulphate or the organic phosphate solution called Hexone, both of which were powerful aphicides, or it is necessary under the Poisons Act of 1900 to sign the poisons register at the stockist from whom you make the purchase. Menazon is a new systemic product just released for sale to home gardeners which comes under the latter category. In the past virtually

all long residual and powerful aphid killers have only been available to commercial growers and others have only been for sale in large quantities. Now, with this new material one of the most common insect pests, to which most of our vegetables, fruiting subjects and ornamentals play unwilling hosts to, can perhaps be more adequately controlled.

Recommended general instructions for application are two level tablespoons a gallon of water, plus the addition of a drop of spreader or wetting agent. A residual effect up to six weeks is claimed if thoroughly applied to the plant and harvesting must not be done within three weeks of use.

As with all preparations used in plant protection, read th j instructions thoroughly before using, handle and store with care.