New Zealand Department of Agriculture.

Manawatu Herald, 3 June 1897, Page 3

New Zealand Department of Agriculture.

JOHN D. RITCHIE, Secretary. LEAFLETS FOR GARDENERS AND FRUITGROWERS, NO. 19. PEAR-MITE (Fhytopus pyri.) By T. W. KntK, F.R.M.S., F.L.S., &c, Lond., Government Biologist.

Leaves attacked by pear-mite are Bo very similar in appearance to those suffering from the microscopic fungus causing pear*scab (Fusicla* ditm pyrinum) that many persons mistake the one disease for the other, and thus the wrong treatment is applied. The diseased condition being due in one instance to a fungus and in the other to an insect, it is manifest that different modes of combating them must be adopted. The pear-mite is very common in thii colony, as also in some parts of Australia. Its attacks may be first observed in the spring or early summer, when the leaveß are Been to present a number of green and whitishgreen blisters, which gradually increase both in size and quantity till there ia sometimes scarcely any portion of the leaf which is not covered by these disfigurements, which have now turued brown in oolour, and look like so many scabs. The brief description of this mite given by Dr. Oobb, the eminent scientist attached to the New South Waleß Department of Agrioulture, is ■o excellent, and describes my own observations and experience in such a clear and lucid manner, that I cannot do better than quote it here :— 11 This little animal is so small as to be almost invisble to the naked eye. With a lens, however, they are soon discovered on almost any leaf whose surface is covered with their blisters. They are seen to be small 1 , white, elongated, slow-oreeping animals, Whole legs, four in number, seem to j be attached near the heads. In motion they present the appearance of dragging their bodies after them, or of an animal pulling a load. They are not numerous on the sur-. face of the leaf, and sometimes several leaves will be examined with a lens before a mite is found ; this is be- j cause they reside in galleries under i theiurfaoe of the blisters, coming out only temporarily, and for purposes unknown. There cannot, however be muoh doubt that they do oome out habitually, for most of the blisters, ( And especially the large ones, have a ; •mall circular hole at the top, which no doubt serves as a door for that

purpose. The blisters of a single leaf often contain several hundred mites. The best way to get a view of them is to let the leaf dry up. This causes them to come out of their galleries, and they may be observed wandering , about in great numbers, or huddled together in soina cranny of the leaf. " There is good evidence that the mites hybernate in the buds, and in galleries on the new wood, they having been discovered in the buds in the winter time; and, having been seen to attack the leaves of the bursting bud in spring, very likely the eggs are deposited in the buds. These points, however, need further observations." The above is exactly what I have myself many times noted; the mites winter over in the buds, and I have some now in which mites have already taken shelter. I have conn ted as many as 802 mites under one scab, but the average, so far as my observations go, is about 200. Leaves from the warmer parts of the colony appear to contain more than those from the South. The mites come from their galleries on the surface more freely in warm dry days than at any other time. The great damage done by these mites may not at first be apparent, but it must be remembered that 'the whole of the attacked foliage is rendered unhealthy and distorted, resuiting in the premature fall of the leaf, and this in turn causes unhealthy trees and a consequent short and imperfeotly developed orop of fruit. Treatment —Rake up and burn all foliage from fruit-trees. This will dispose of many insects besides the mites, also myriads of fungus spores, thus preventing the spread of disease next season. After the leaves have dropped, spray thoroughly with kerosene emulsion; repeat just before the buds burst. The above I have found usually quite effectual, but, should another dressing be deemed necessary, spray again just after the petals fall.