DISEASE AMONGST FRUIT TREES.

Tuapeka Times, Volume XVII, Issue 1027, 26 March 1884, Page 5

DISEASE AMONGST FRUIT TREES.

(" Adelaide Observer.") The alarming increase of disease amongst our fruit trees during the last few years is a matter that ouyht to be takpn seriously into consideration by every grower and by every other person interested in this most important industry of fruit cultivation. It is weak and childish to quietly fold the hands and to complain, it is equally weak to attribute the diseases to causes over which we have no control, to say that they are occasioned by " climate" influences, to " decay of the species, exhaustion of the soil, weakness of the trees, &c." We know through inqnirios made into the matter and the consequent revelations made by scientific men, that most of the diseases in orchards are caused through attacks by insects or fungi, many of which are similar to those affecting trees in other countries, and which most probably have been imported along with trees and plants from those countries. Very often it happens that a comparatively harmless insect or fungus of one countiy becomes a perfect scourge when imported into another, because in its new habitat it is not subjected to the attacks of its natural enemies which keep it within bounds in its own country. We do not doubt for one instance that when trees or animals are sickly and weak from any cause whatever, they are mo3fc likely to be attacked by parasitic and other enemies ; but it is equally without doubt that the same enemies when in sufficient number, will weaken and eventually kill even the strongest animal or plant if left without molestation. Diseases of plants are cOntagiou3, infections, and transmissible, and the Colorado beetle has been conveyed long distances in packages. The Codling moth, the Hessian fly, and very many insect pests have been introduced into different countries, and have wrought enormous mischief. The bacillus affecting j orange trees was almost certainly introduced into Sydney, and thence into this colony, and so was the "shot hole" fungus affecting the apricot tree, and the " curled leaf " of the peaches ; in fact, we know not how many of the diseases now affecting our orchards have .been introduced by importers. When the colony was first founded there were no diseases amongst our fruit trees, but it must be admitted that there were very many seedlings — which are certainly the strongest — and that a large majority of them were of no value, and therefore very hardy. It not unfrequently happens that the finest, most showy, and earliest fruits are also the weakest, and most liable to be the product of weak or unhealthy trees. Early ripening fruits are most likely to be weak — or have a tendency to disease greater than those that are later in maturing, and when the seeds of these are again sown to Becure even earlier varieties the weakness is transmitted and intensified. Sometimes diseases in fruit trees are conveyed from one tree to another in budding, grafting, and even through innoculation by the pruning knife and saw ; but in the case of insect and fungoid pest 3 they may be carried by the wind or by birds upon, their feet and legs, or even by insects snch as bees when going from flower to flower, or they may be purposely carried from plant to plant by auts, as is done with aphides, scale insects, and coccidoe. Diseases in fruit trees may also be occasioned by poverty in the soil through neglect to supply manure to compensate for what is taken out by the tree year after year, or there may be a natural lack of some constituent in the soil, such for instance, as potash, which is almost absent in the soils of this country. This is very necessary to fruit trees, especially apples, and ought to be supplied.