PLANT DESTROYERS.

Otago Witness, Issue 1682, 16 February 1884, Page 6

PLANT DESTROYERS.

Although some of the diseases to which plants are subject are alike mysterious in their origin and their operation, and above and-, beyond our control, there are others which we can trace to their source, and apply measures ' to check or remedy their depredations. The potato disease in IS4G made ita appearance in a night in several localities distant from each other, and spread imall directions with alarming rapidity, crossing seas and mountains without check or hindrance, leaving behind it a mass of rottenness and pollution which was sensibly felt for miles around. Fortunately it has disappeared, and with all the researches which the mosb eminent scientific and practical men have made, no one can tell whence it came or whither it went. Many theories and speculations we're advanced — the most plausible and likely being a secret atmospheric influence — but no one has positively solved the difficulty. This Colony happily was exempt from that scourge. Had it ravaged the cultivations of these islands as it did those of the British Isles, so far removed from other sources of supply, and with commnnicationa co rare and occupying so much time, and with both the Native and European population depend- • ing so much for their dusfcenance on that esculent, the results would have been terrible in • the extreme. At the present day the effect would not be so disastrous, as many other food plants are extensively produced, and communication with other places is frequent and rapid. Elemental influences are absolutely beyond control, but are . nevertheless in too many cases terribly destructive. A night's frost or hot winds, hail- showers, excess or absence of rain, tell their own tale either directly or by producing secondary agents, principally insects, to complete the havoc. Rust and smut in wheat and oats may be ranged among the more secret diseases which I do large damage to these cereals, but as these are traceable to a faulty condition of either seed or soil, they are capable of being pro- [ vented or remedied by the exercise of a little skill and attention on the part of the cultivator, and if ordinary prudence were exercised might possibly be eliminated from the host of enemies to whose attacks the agriculturist is exposed. The attacks of caterpillars, small birds, rabbils, and other introduced posts are productive of immense loss to the farmer. The caterpillar at my cometh as it listeth, and locates itself on a spot without any previous warning, with the result on the crop — Whereof enough to fill his hand The mower oannot find, Nor can tho wan his bosom fill , Whoso work is sheafs to bind. The raids of this scourge cannot be foreseen nor prevented ; when they do appear, burning them off or drowning them out appear to be the only remedies. The birds, rabbits, and similar vermin add a heavy score in their contribution to the destiuction of the hopes of the husbandman. These have been introduced into our midst with a high hand, and their extirpation with as high a hand is imperatively necessary. To shoot, poison, and destroy them and all their belongings appears a bounden duty on all who can handle a weapon. No doubt as regards the rabbits this is the case : if wo do not destroy and keep them under they will eat us out. In the matter of the birds, however, great discrimination requires to be exercised. It would be madness to kill right forward"; by so doing some of the farmers' and gardeners' friends would be annihilated, and the last state would be worse than the first. A large number of the insect pests are kept down by means of the small birds, and letting loose the dogs of war among them would be madness in the extreme — destroying friends to the advantage of enemies.

Passing from these larger classes of destruc-tionit-ts to a smaller one— the fungi, constituting an order of plants of peculiar organisation and manner of growth, and which vary greatly in sizo, form, colour, and consistence; of parasitic habit, growing on other plants and substances, and* doing an immense amount of mischief, producing not only the diseases already alluded to — rust and smut — but many others of a similar character known as mould, mildew, brand, dry rot, &c, and for tho cure of which many remedies have been suggested. Some naturalists attribute the presence of these fungi in their various forms to conditions of the soil, from its being too rich, or the want of proper drainage. Besides damaging the cereals named, thiß pest affects fruit trees and smaller plants, ruining the fruit or destroying the plant altogether. I Perhaps the most insidious, numerous, in- [ jurious, as well as the most difficult to over- | come, is the genus of insects zoologically named aphis. These are all highly injurious, living on the juices of plants, which they suok with their beaks. These beaks, although quite indiscernible to the naked eye, possess extraordinary power, piercing not only the soft and fleshy skin of roots and leaves, but also the hard and tough bark of forest trees. Our Province has in its sjjort history been overrun by many varieties of this pest, fn earlier years the Provincial Council of Otago passed an Ordinance prohibiting the introduction of apple trees affected with the American blight, but in spite of this legal interdict the blight got into the gardens, running riot according te its own sweet will, and accompanied by red spider and scale, which are not likely ever to be completely eradicated. A similar plague for a while affected our stately gum trees, and if,t the door of the blue gum was laid the charge of ip&icting the cabbage, turnip, and others of the Br&s&ica family. The idea was absurd, but for a good while obtained popular belief. Fortunately this class of' aphis seem to have run their gauntlet, and do not appear in such force and to such a ruinous extent as was their wont. It is to be hoped that the pestilent fellows now preying on our most valuable introduced timber tree, Pinus sylvestris (Scotch fir), will as spAa,sily and completely pass away. None of them p jjgtural to our country, but have by some inscrutable process been introduced into our midst, disheartemag £he labour and blighting the prospects of the nusb&njjjpian. Yet another species of injurious"ih"ije&i;, which ! fortunately has not yet been noticed herej but jphich we may look for, and which has proved by fat* the most destructive in older countries, remains to Jpo noticed, and it were well that I our f armera should keep a sharp look' out for I it : this is* the turnip fly. The ravages committed by tHe iflnumerYvble hordes of this tiny | insect amongst the turnips in 'Britain a short ,tim.e ago can hardly be credited : still the fact jpjjsj; Jae &§f»%M<l f as ft js' vouched 'for' ,b^i Q .

disputable testimony. Tho now departure from old methods caused iv our farming industries by recent discoveries and inventions will make root crops in New Zealand equal in importance to our cereals, and it behoves all interested to turn their attention to tho prevention of diseases from getting a hold on them rather than labouring to eradicate them after being introduced. This, duty devolves on our scientists as much as on practical men. The efforts of both are urgently demanded, and the &ooner action ia taken the better. We have in our midst several societies on whom this duty has special claims, and foremost "amongst them is the Acclimatisation Society. Tho special labours of this body are now pretty well completed, and tho judgment of the public on the results achieved by the Society according to the point from which they are viewed. Some will applaud ; others will 'condemn. Let this Society now tur«i their attention to the means of prevention and destruction of insects injurious to plants, and their labours in this direction will meet with universal approbation. In this matter the student and the practical man must work together ; and while we cannot expect to get rid of the injurious insects altogether, we may fully anticipate not to bo necessitated to let them ravage our crops at their pleasure. We need no teaching as to how a crop insect injures, as that part of its life history is commonly only too plain. But where is it at other times ? Where does it pass the winter ? How deep does it go down into the ground ? These are important questions. The importance of a knowledge of the habits of our crop insects and the using of our common sense to counteract their ravages, are matters of imperative necessity to all.