THE ORCHARD.

Pelorus Guardian and Miners' Advocate., Volume 26, Issue 62, 30 July 1915, Page 7

THE ORCHARD.

WOOLLY APHIS (SOHILONEURA lauigbr^). One of the greatest enemies to be met with in an apple orchard is the woolly, aphis, or American blight. These insects may he found abundantly in old and neglected orchards, where the \trees infested by them ..become so damaged by their attacks, that they appear as cankered., almost lifeless trunks. The insect, however, does not confine itself to old trees or neglected plantations, hut may be oto 7 served on trees at any stage of their growth, and in almost any locality. To the naked eye a colony of these pests appears as a ibass of white cottony substance .attached to the trunks, limbs, or twigs. On carefully examining a portion of the woolly material it will’be seen that it contains numerous small plant lice in all stages of development. This cottony substance blows about easily in the wind, and may be carried thereby for a considerable distance, thus insuring a speedy infection of trees in the immediate neighbourhood.

For years young nursery stock has served as a means of introducing this pest into districts previously unaffected, until now this enemy of, the orcbardist may be found in any corner of the globe where apples or pears are grown. . The aphides lire In numerous colonies on the trunk, limbs, and twigs of the apple tree. By piercing the bark with their sucking tubes and extracting. the .sap they so reduce the vigour of the tree that death is the ultimate result if some means of control are not immediately adouted. The irritation set up in the tender tissues by the feeding of the insects has the effect of producing swollen cankered like growths on the tree, which are sometimes mistaken for an attack of true apple canker, but the nreeence of the downy-covered insects in the cracks of the affected parts will usually warn the observer of the real source of the trouble. Like all other aphides this species is capable of exceedingly rapid reproduction, and a small colony this season, if allowed to multiply un-. checked, may mean Infection of the whole orchard within the next year. The adult female is wingless - and capable of ' producing living young without Iht agency of the male. In a little time these young attain the benroductlve stage, when they can themselves 'produce living young. Many generations may be ' thus brought into being in one season, and it has been estimated by one of our leading naturalists that one insect in the course of five generations may be- the progenitor of over 5,000,000,000 descendants.

Climatic conditions have a very marked effect upon these insects. Long spells of dry, hot weather such as are experienced in many parts of the Commonwealth and; New Zealand are very favourable to them, and as these conditions also check the growth of the trees' attacked, the aphide If allowed to breed unchecked, will soon overcome them. METHOD OP CONTROL.

If tackled in its earliest stages this pest may be eradicated with a minimum of labour and expenditure as compared with the time when it has gained a good hold on the trees. As soon as any of the white woolly material Is observed on any of the trees, paint these over with red oil femulslon, using a stiff bristled, brush. Spray thoroughly when the tree'i are dormant with the same substance, and in places where the insects have embedded themselves In the cankered outgrowths produced by their attack, acruty out all the crevices with red v oil undiluted. In spraying, considerable force must be used in order fo penetrate the woolly covering with which the insects surround themselves.