ENTOMOLOGICAL.

Otago Witness, 14 December 1893, Page 4

ENTOMOLOGICAL.

The Root Fungus (so-cjilled). There is in the North Island a fungus that attacks the roots of many varieties of trees and plants, and which is well known and widely spread amongst the orchards. Unlike most fungi it delights in very dry ground-in fact, dry ground is the only situation in which it will live, and irrigation is one of the very few cures for it, and probably the only reliable one. In many parts of the colony the loss from this fungus has been very great, and at ose time a former Government were prevailed upon to £ ™ * talent ?* scientific man to investigate the matter, with a view to discovering some ™™ I V V**' unfort ? na^ly. a much to! common mistake was made in selecting a gentleman who, although a well-known and deservedly highly esteemed systematic botanist of the highest standing, was neither a mycologist nor a student oi vegetable pathology, and the natural consequence was that, in spite of every care and attention, no very beneficial remedy resulted. *

The situations most liable to attacks of the root fungus are patches of dry lf n .- an u d IJ t front of a bu sh, where the timber has givtn place to the fern, and it 18 worst where certain varieties of trees have been growing. The first signs of the fuDgusis in dead patches of fern, and when the land has been dug and sorrel grows on it patches of this plant will die out, the tops wither, and, if handled, will ba seen to have no hold on the ground, because the roots have been rotted of. The fruit trees will start to grow well, and look perfectly healthy, till some day you will observe a fine tree with halfgrown apples in plenty, and you will imagine that they look very well, but have for some time ceased to increase in size, and by-and-bve the leaves will look a little yellow, and will be easy to shake off. If you give the tree a push, it will fall over on its side, or some morning you will find it lying flat on the ground and examination will show that the roots are completely rotten, and broken oft' by the weight of the tree. The collar, cr part of the bark immediately above the ground, will be soft, and will come off if handled just as if it had been cooked, and it will be seen to be quite rotten, and probably putrid. All the roots immediately next it, for some distance round, will bo in the same condition, and broken through, and the disease will seem to have died out towards the ends, leaving those at a greater distance more or less apparently — apparently only— sound ; but the tree will never recover, and any new tree planted in the same place will very soon die from the same cause. Sometimes shortly after a tree dies the one next it in the same row is taken ; sometimes ifc is another further off, or in another row, and once the disease has begun you never know where to look for 4he next victim. It may creep up a whole long row and clear oft' every tree in it, or it may pass over one or two, or abandon that row for the present and leap over to another, or break out in quite a different part of the orchard; but, at all events, one thing is certain, that when once the root fungus gets fairly started in an orchard, there is an end to all feeling of peace and security, and before very longit will be safe to count upon the ruin of the entire orchard, for even if it leaves off destroying the trees for a few yeare, it may come on again any time, and after you have begun to hope that it has left you, you will again see fine trees covered with valuable fruit suddenly going down before it. It kills all kinds of fruit trees and many other trees, but the apple seems to be a peculiarly favourite victim, and, so far as the writer knows, there has been nocase of an apple tree, once attacked, ever recovering.

The disease is caused by the mycelium of a fungus, which (from the Government investigation alluded to) was supposed to be Lycoperdum gemmatum, or what is generally known as the "puff ball," and called in Scotland "the devil's anuff box" (from its being full, when ripe, of a dry powder somewhat resembling dark-coloured snuff, which ia in fact its spores, or seeds). This, however, appears to have been a mistaken identification, although the true nature of the fungus has never been fully understood. It was also reported that the peach, if grafted upon the plum, would not be attacked, and that, if places where tree 3 hid died from the disease were liberally saturated with water impregnated with Stockholm tar they copld safely be replanted with young trees ; bui experience has amply proved that this is no protection whatever against an attacn', — which indeed is sure to occur.

The only instance that the writer ever knew of a cure was in a few cases where the ground was liberally and frequently saturated with Trerosene emulsions, and in one or two cases where the somewhat desperate experiment of using pure kerosene was resorted to. This applies to apple trees, but the disease does not seem quite so fatal to a few other varieties. For example, the white thorn suffers severely (as much so as the apple), and the writer has often known whole fences of it laid prostrate ; but on one occasion when the fungus had got into a young thorn hedge, and destroyed every plant right along, a number of rooted cuttings of the common monthly rose, which had been panted at intervals of 6ft apart amongst the thorns, enfciiely escaped, and continued healthy ; and also a large number of pine trees (chiefly Insignia and Maritimus (planted along the same hedge ultimately esraped death, although their leaves turned yellow and dropped eff, and for a long time the trepß seemed to be doomed. Eolh sulphur and quicklime are very good preventives. They require to be used in very largo quantities, but neither of them can be called remedies, as a tree (notably an apple tree) once fairly attacked may be looked upon as incurable, and the only instance to the contraiy was one in which a farmer in the Upper Thames Valley, seeiDg that a neighbour's orchard ciose by was being destroyed by the fungus, took alarm and had all his apple trees (younger ones) dug up and removed to some very wet ground in another pait of the farm, where they have grown and thriven very well ever since. In this case the trees were in some instances found to be slightly infected when dug up, and they were placed for some days in a rapid stream to thoroughly cleanse the roots, and then planted in land so wet that one would not have expected apple trees to prosper in it. But they did, and to-day they are about 12 years old and loaded with very fine fruit, and no fungus ia to be seen near them up to the present time,

This root fungua is a very serious evil in the Jtortb. Island of New Zealand, and causes many settlers great losses, and scientific men in most other countries who have been consulted seem to look upon ib as a most interesting and important matter, both from a scientific and au economic point of view. Unfortunately our Department of Agriculture docs not seem to include any person able to deal with matters of this kind, and it is most probable that we shall have to go on submitting to such losses until some improvement is made in this direction. So far as the researches of the writer and certain of his colleagues go, it would appear that the mycelium of the fungus seems to originate tipon some piece of wood, bit of dry root, or some such tbing buried in drtf ground where there is no moisture to destroy it, and that it spreads thence until ifc lays hold of a p'ani cr tree root, upon which it fastens and increases. The best method of dealing with land likely to be invaded by the disease, is to pultivate it very carefully and remove all dry fern roots and all other substances likely to harbour the disease in the first placs, and to dress the land very heavily with both sulphur and lime, and also when planting trees to dress the roots frequently and copiously with korosene oil emulsions, or, if possible, to irrigate the soil, because the root fungus never attacks anything growing in damp land, and orchards very bad'y infected are always saved by removiDg the trees to very moist l*nd. Entomologist.