FRUITGROWING.

Star (Christchurch), Issue 12084, 13 August 1917, Page 3

FRUITGROWING.

INSECT PESTS IN" THE ORCHARD AND SOME EFFECTIVE REMEDIES. VALUABLE HINTS TO ORHOARDISTS. (By FRUITICUS.) Every fruitgrower should make himself well acquainted with all tho pests in his orchard, as well as those of other districts, likely to spread to his own. Education is the purpose of tho present series of expert articles.

No doubt tho majority of orchardists arc busy at tho present time with their spray pumps, trying to control tho various pests and diseases found in the orchard." I't is very surprising to find how few orchardists have any knowledge whatever of the pests they are, spraying for. They know there are certain pests in the orchard, and have seen or "heard of tho best preparations to use for their eradication, and consequently they go no farther, never thinking that a knowledge of tho lifehistory, habits, etc., of the pests will help them very materially wheu spraying. Every fruit grower should make himself well acquainted with all tho pests that exist in his orchard, as well as of those found in other districts, and likely to spread to his own. LIFE HISTORY AND HABITS. All the inseot pests tha't are known as " aphids" (woolly aphis, green aphis, black aphis, etc.) have very similar habits; their structures are very much the same, and they require tho same remedies to suppress them. These aphids get their food by inserting a sharp beak or proboscis through the bark of the tree and sucking the sap, and are commonly classed as sucking insects, as a distinction from those pests that obtain their food by eating. Aphids never eat the tissue of the leaf or fruit. Throughout the spring and summer these aphids are constantly on the increase by giving birth to living young. If eggs are laid at all, they are deposited by the last brood of females in the autumn, and remain fertile all through the Avinter, to hatch out in the warmer days of spring. In this way tho pest is carried on from season to season. In the majority of cases a singlo female insect gives bitrh to from 100 to 160 young, and as these young only take from ton to twelve days to mature after being horn, it will readily be seen 'that the plant lico known as aphids are capable of increasing with wonderful rapidity. This accounts for tho fact that nearly all the aphids may he killed from a tree, and that tree be very seriously infested again within a few weeks. On account of this, growers should aim at destroying all tho insects when spraying, even if more tune and material have to be used than thought necessary. Usually tho last brood in the autumn consists of about one half males and one half females. As beforo stated, *hese females deposit the eggs over tho winter, and tho insects die.

There is one great exception to this rule, however, and, unfortunately, it concerns the most destructive of all the aphids. This is woolly aphis. The woolly aphis lives over the winter as young or partly-grown insects upon the branches and in the crevices of the rough bark. More of the life history of the woolly aphis will be given when dealing with the different pests. The eggs of aphids usually hatch out a. little before the leaf lias burst in the spring. Ilicy are almost always wingless, and are known as stem mothers. Those stem mothers mature in a very short time, _ and, being females, give birth to living young, thus constituting the second brood. This brood lives and thrives all through the summer months, and are nearly all wingless. These in their turn give birth to living voting, tho females of which deposit an'egg. And so the cycle goes on, season after season, year after year, unless some outsido agency in tlie form of spraying intervenes and prevents them. Nearly all the aphids excrete from their bodies a sweet liquid known as " aphis juice." or "honey dew." This liquid can be seen on tho leaves, and often on the fruit, giving the leaves a shiny appearance as though varnished, and making them very sticky. A fungus known as "sooty fungus," usually makes its appearance in tho honev dew or juice deposited by the aphids'. Tn districts where an'ls are common, thousands of these insects may be seen travelling up nnd down the branches of aphisinfected trees. At ono time it was thought that, these ants were instrumental in getting rid of tho aphis, but it has since, been found that the an'ts are fond of tho juico. and are- cnrefjul not to injure tho insects that produce it.

Aphids are considerably lessened in number each, year by insect, enemies, although not to tho extent desired by the majority of growers. Several species of flies are known to live on the insects, and the ladybirds are particu--larly fond of them; hut unfortunately, none of these natural enemies do sufficient good to enable the grower to dispose of his spraying apparatus, although ladybirds especially, should bo carefully protected. Tho dittle bird, known as "silver eye," or "white eye," is also very partial to some of the aphids, especially woolly aphis. EFFECTIVE REMEDIES.

The most common remedies for tho destruction of aphids, and those that) can bo thoroughly recommended, are ied oil emulsion, tobacco washes, ami kcroscno emulsion. An insecticide that will destroy one aphid is usually successful in destroying any of tho others if a thorough is rr.ado and every insect is reached with tho spray. As the winged insects fly very freely during tho autumn it is most important that all the orchardists in a district spray their trees. Failure on the part of one man often results in his orchard becoming a good breeding ground for the whole community. Cooperation, then, as in every branch of the fruit industry, is most essential in any campaign against tho insect pests that infost the orchard. "WOOLLY APHIS, AMERICAN BLIGHT Oil WHITE BLIGHT.

This, no doubt, is the most serious! of tho insect pests tho orchardist has to deal with in New Zealand. It occurs in practically every district where apples are grown, although, owing to climatic conditions, some districts are more nearly immune than others. Tho Auckland province and Nelson district are very subject to bad attacks, while its damage is not nearly so bad in thd south or colder parts. It is a barkfeeder, living on tho trunks and limbs of the trees, but does not feed upon the fruit or foliage as is the case with

some of our orchard pests. Although not attacking either loliago or fruit, tJie results of its work oan he. easily seen in both—on the leaf by the restriction of sap, causing them to jag and fall prematairelyi; and on the fruit by being small and improperly colourod for the same reason. It is easily recognised on account of its being covered with a white, -woolly secretion, which has suggested its common name. The aphis attacks cither the tender hark about the scars on tho tree, or the bark of tender new shoots. When very abundant, large swellings are produced upon tho limbs, these being duo to th»> thickening of tho inner bark. Probably the most injury is done to thp •tops of the trees where tho teriden' growth is, and in many instances the buds are destroyed entirely. The life history of the woolly aphis tr.ay be briefly stated as follows: — Early in tho spring there will be some wing insects in protected places, beneath the bark', or even under the dead bodies of the aphis that were killed or died the previous season. These insects are usually very small, as compr.red with others that follow r . By tho time the buds begin to open in tho spring these insects will locate themselves in the tender new bark, and begin feeding on tho sap drawn from the tree by means of their beaks, growing in size, and producing tho woolly substance on their bodies, making them look like mouldy specks upon the bark. Tho insects iucreaso von' rapidly in numbers, and very shortly 'the tree may bo so badly infested, and tho •woolly secretion so heavy, as to hang down and even fall from their bodies to the ground. The aphids aro all wingless until February or March, when, by careful observation, a few winged insects may be seen. These leave the tree and fly to others, thus spreading infection. Each of the winged insects gives birth to males and females, and before winter comes on each female either deposits a single egg and dies, or gives birth to young which remain small until the following spring. Although it is almost impossible to completely eradicate woolly aphis when once it is established in the orchard, it must be remembered that every insect can bo killed if reached by the spray, but sufficient force must be applied to remove or penetrate the Avoolly covering. As before stated, red oil at a strength of ono in It) or 12 during the winter is very effective. Kerosene emulsion at ono in 15 or 17 is also good, the kerosono having very penetrating properties, whilst during the spring and summer tobacco wash can be used with no fear of turning tho foliage. BED MITE.

Red mito is commonly known as red spider, but is then, wrongly named, as the red mito found in the orchards does not spin a web. This mite attacks several kinds of fruit trees, although most prevalent iff the apple. Tho eggs of the red mito are of a bright red colour' and very numerous. They are usually deposited in tho crutches of the tree, or just below the buds all along tho limbs. Hie eggs hatch out as soon as warm weather conies along in the spring, and the insect is of a bright red colour, but soon changes to a dull brown. The chief injury is done to the foliage, the mites puncturing tho epidermis of tho loaf and sucking the sap. This causes tho leaves to turn a sickly colour and yellow, owing to the rupture of tho cells The leaves fall prematurely, and thus the whole tree is affected. Fruit grown on trees infested with red mite is often small. The mito is particularly fond of the Sturmer and Delicious, and often clusters of eggs can bo seen either at tho calyx or stem end of those varieties. It is not a hard pest to control, neither is tho damage so great as with the woolly aphis, but, as "every fruitgrower knows, impaired vigour of the leaf, from whatever cause, moans an impaired tree, and consequently every effort should be, mado to keep the red mito under control. Both red oil and lime sulphur are very effective when dealing with this pest, and should it be necessary to spray during the summer months, atomic sulphur at the rate of six to eight pounds to 100 gallons of water will help to keep it in check. ' , MUSSEL SCALE. This is one of the worst of the scale pests in some parts pi' New Zealand. It was originally a European pesi, was introduced into America many years ago and was undoubtedly brought to New Zealand from America. It appears on tho tree in the form of a small scale about one-sixth of an inch long, brown in colour, closelv resembling the bark ot tho tree, and shaped like a mussel. Under each scale may be found a mass of eggs, from twenty to ono hundred. These c«gs are white in colour and globular. "Before hatching they turn yellow soon after -which young insects appear As it becomes warmer the young leave tho parent scale and crawl oyer the twigs and tender branches, looUinK for a suitable place to lodge. Ibis usually happens from October to December, when even a weak spray will be effective in killing them. The .insects soon become fixed to the tree where by inserting their tiny beaks they suDfiist upon the sap of the tree. Bciom the end of the season each insect, has secreted for itself a scaly covering, and the female becomes little less than a bag of eggs. The process ot depositing these soon begins, tho body of the parent shrinking day by day until finally it becomes a mere atom at tho narrow end of itho sale. There is only °n° brood annually, and great numbers die naturally every year. Tho male insect is much smaller than the female, and when full grown leaves his scale in possession of two wings, his sole purpose being to fertilise the female, after "which he dies. (To be continued.)