«Work in the Garden»

Lake County Mail, Issue 32, 14 January 1948, Page 7

«Work in the Garden»

Commando Raids on Pests

Now, as the year draws to a close, the summer garden begins to take shape. The vegetable garden is almost full. The small fruits arc maturing, and the flower garden is showing the early summer colour.

The warm and dry conditions of early summer usually assist us in the control of weeds, and garden maintenance will be well forward. In this state it is easy to keep everything in order with very little effort. Do not relax entirely. Keep a critical eye open for the odd weed that usually appears. Keep the lawns fairly short to prevent long stalks getting away. When the garden is full and growth is strong, a fungus or insect attack may mar the finest efforts. Busts, mildews and a whole host of caterpillars may make their appearance.

Spraying, then, is priority number one immediately before or during the holiday season. For general garden purposes pests and their means of control are grouped under three headings:

Sap-sucking Pests These include aphis, which may be found at times on almost any garden plant or tree. They and the following have a very fine probiscus or beak with which they pierce the outer surface and suck the plant sap. They do not eat the leaf surface, hence arsenate of lead is useless as control. The most successful method of attack is to block their • breathing passages. With aphis in small gardens, Black Leaf 40 or other nicotine sulphate spray may be used. This is one spray that should be applied when temperatures are high, as the fumes the pests. Derris dust is effective, particularly on lilium and similar plants, where the pests have less cover in the way of leaves, thus ensuring a good contact of dust with aphis. Kerosene emulsion is now used less than formerly, but it is a cheaper and effective spray where the garden is large. There are several recipes; the following is one I have used successfully for many years: —Dissolve 41b of soft soap in one gallon of boiling water. Then, whilst still boiling, add one gallon of kerosene and churn until it becomes a creamy white emulsion. This may also be done by pouring the mixture into the spray pump and pumping back into the bucket with the jet open. This stock mixture should be diluted to 24 gallons. It is considered to be more effective if applied warm. Thrips are small, black, sap-sucking insects which attack a wide range of plants. Their wings are very narrow and margined with stiff hairs. These give them another common name, fringe-wings. Their depredations show a lightening in leaf colour which eventually takes on a silvery appearance, particularly noticeable on rhododendrons and other large leaves during a dry period. They are readily controlled with nicotine sprays. Leaf-hoppers are small, green or yellowish sap-sucking insects which hop or leap to safety when the foliage is disturbed. They attack a wide range of plants, particularly apples. Their presence is shown by yellow patches showing on the leaf'surface and they may readily be seen if the foliage is disturbed. There again, nicotine sulphate is the means of control. Scale Insects and Mites

Scale insects belong to this group and attack many plants. A few are fruit trees, including citrus, gum trees, oak trees, camellias, cabbage trees, Oleanders, daphnes and rose.s. They may be observed on close examination. If they, or aphis, are present in numbers they will be detected by the sticky nature and blackened appearance of the shoots. This is caused by a sootymould, which grows on a sweet sticky substance excreted by scales or aphides, and termed honeydew. Scale insects take their common name ifrom the various scales; encrustations or mealy coverings they have to protect them Many of these do serious damage, though a few apparen f ly do little to harm the healthy appearance of their hosts. M'mv scales have natural enemies, including the various kinds of

By J. W. Goodwin, N.D.H., N.Z., F.E.H.S., Massey Agricultural College

ladybirds and the parasite habrolepsis, introduced l>y the Cawthron Institute a few years ago, wliich controls the Golden Oak scale. Spray control on decidious plants is by red oil in wintortiine. For evergreens and decidious plants in leaf use summer white oil, according to the makers’ instructions. Mites, or red spiders, belong to a different class of insect, but for our

purpose they arc sap-sucking. They vary from microscopical to large enough to be seen with the naked eye. Many of them develop protective coverings and it is only during the migratory stages that they may be readily controlled with summer oil. Red spider is a mite wliich attacks a wide range of plants, particularly violets and boronia. Nicotine sulphate sprays are probably the most effective.

All of these pests should be reduced to a minimum, for it is during their movements from plant to plant that “ virus ” diseases are more often transmitted. Chewing insects Caterpillars in large numbers will take a rapid toll in the garden. They have many natural enemies, particularly birds when feeding their young. There are also several small wasps and flies whose young are parasitic on caterpillars. The lace-wing flies are very beneficial in the destruction of aphis and are often called aphis-lions. Caterpillars may be checked by nicotine sulphate and derris dust sprays, but the cheapest method is to spray with arsenate of lead. This, of course, is not advisable on mature vegetables, as it is a poison. In such cases derris dust is the safer treatment. The caterpillar or the white butterfly is well-known.

During the summer the diamond backed moth may make its appearance. It is a much smaller moth, and the caterpillars, about three-quarters of an inch long, will drop by a silken thread if disturbed. Cabbage and its allies may be attacked, particularly wallflower. Good progress has been made in recent years by the introduction of parasites to control both of the above.

Leaf-rolling caterpillars of several kinds are also plentiful and may be found in rolled or folded leaves. Beetles and the pear or cherry saAvfly may also cause considerable damage. Arsenate of lead is the answer. Leaf Miner and Fungus I may just have room for another pest which appears at this time of the year —the leaf miner. This is the maggot of a fly resembling a miniature housefly which may be seen hovering above chrysanthemums, cinerarias, carnations, viscaria, dianthus and other allied plants. The first indication of attack is a thin white line on the surface of the leaf, which indicates the movement of the maggot just below the surface. Sparys of nicotine sulphate or arsenate of lead applied for other pests may take a small toll, of these pests as they hatch and just before they enter the leaf. Once outside, the oifly method is to remove infected leaves or pinch the end of the white line and kill the maggot. The plants should be dusted with derris dust, as a deterrent to the flies, as soon as the trouble is noticed. I have, frequently seen plants recover from first attacks when protected in this manner. The flies do not like derris and will probably lay their eggs on milk thistles or weed allies of the protected plants. Fungus diseases are always ready to develop to epidemic proportions when conditions are suitable. Most fungus diseases cannot be cured once infection has taken place. Diseases may be controlled and be prevented from spreading by the use of Bordeaux, copper oxides or sulphur sprays at summer strength. Colloidal sulphur is probably the best spray for mildews and rusts, with Bordeaux in preference for black spot. However, they are all good effective and fungicidal sprays. Quite a wide range of garden plants may be attacked, and, remember, get in early, for it is only when 'the young minute snore of disease i«» germinating that i f ’can be killed bv a trace of t’ ■e cidal spray. Sprayin'-, reh nicotine sulphate, flier,!?: ‘ p.ncc on page S,