The question of the management of old and decaying trees in urban and suburban districts is one of considerable importance, and which, possibly through ignorance, rarely receives the attention it deserves.

From various causes, apart from atmospheric conditions, such as poverty or poisoning of the soil, attacks of insect and fungoid pests or accident to limb or stem, old trees may become stag-headed, hollow and unhealthy and, if not promptly attended to, may die out altogether. Probably the most prolific cause of decay arises from non-attention to wounds on the stem and larger branches which have been brought about by the wind or other agency. Where a branch has been broken off, the greatest care is necessary to prevent rain entering at the wound and so setting up decay; and, to avoid this, the point at which the branch was broken over should be made smooth with a pruning knife or saw and covered with an antiseptic to prevent the ingress of damp as well as aid in rapid healing. Old Elms suffer most in this way, less so the Oak, Beech, and various other trees; indeed, there are few public parks in any of our larger towns where decayed and dangerous Elm trees are not to be found, the majority of which have become diseased and rotten at the core by the ingress of water at the point where a branch had got broken off by the force of the wind and have received no attention in the way of pruning and painting.

The simplest and most successful method of dealing with hollow trunks is to clean out carefully and thoroughly all dead and decaying matter, and when quite dry the interior of the shell may be painted with creosote; then fill up with a composition of one part of Portland cement to three of clean gravel and sand, the surface coating containing a larger quantity of cement. As cement usually shrinks from contact with the wood, a coat of tar between these will be found useful, and cracking of the concrete surface may be prevented by an occasional coat of paint, the colour of which should imitate, as nearly as possible, that of the natural bark. In trees where decay is not too far advanced, and where the bark is likely to grow over the artificially filled hollow, the concrete should . only be brought up flush with the healthy bark. On examining lately several large Oaks and other trees which were treated as just described some twenty years ago, the results quite justify the method adopted.

Those having charge of trees should never allow the stems to be covered with soil, neglect of which has been the direct cause of the decay and death of many noble specimens throughout the country. Where it cannot be avoided, and the instances are few, dishing will assist - that is, the soil heaped around the trunk should be formed into saucer-shape, the rim or edge being at a distance of 6 ft. from the tree trunk.

Where poverty of the soil is the cause of early decay in a tree, much good may result from carefully removing the existing soil from amongst the roots and substituting that of better quality, preferably of a loamy description. A small quantity of thoroughly decomposed manure may be incorporated with the soil, but for trees generally the amount used should be very small. In removing the exhausted soil it is a good plan to cut a trench, say 2 ft. or 3 ft. wide, just outside the root boundary and then to carefully work inwards amongst and beneath the roots with a pick or fork, the greatest care being exercised that no damage is caused to these when carrying out the operation - which is simple enough in the case of young trees, but very difficult where old specimens with long stout roots have to be dealt with. The new soil should be carefully rammed in amongst the roots and made perfectly solid.

Of insects that are injurious to trees, but especially such as are in an unhealthy condition, the goat and wood leopard moth (Coccus ligniperda and Zeuzera cesculi), the Elm bark beetle (Scolytus destructor), and Oak leaf roller moth (Tortrix viridana) are those that give most trouble in our larger towns and cities. All these are plentiful in London and frequently much damage has been done and many fine old trees rendered unhealthy, or killed out by their depredations. The Elms suffer from the attacks of the goat moth and bark beetle, while the wood leopard moth has caused incalculable damage to Chestnut, Thorn, and various members of the Pyrus family. Oaks are frequently defoliated by the Oak leaf roller moth which appears in certain seasons in vast numbers and feeds on the leaves of the tree. Where a large number of trees is attacked little can be done, but in the case of isolated standard specimens much good can be brought about by spraying, hand-picking and shaking the trees, the moths being collected and destroyed.

The goat and wood leopard moth, by tunnelling into the stem and branches, render the trees, particularly young specimens, liable to snap across at the point where the grub entered; and in our London parks and gardens young Thorns, Chestnut, Poplar, the Beam tree, and other species of Pyrus have suffered greatly in this way. As before stated, by placing a small quantity of cyanide of potassium in each tunnel, the insect will quickly be got rid of.

The Elm tree destroyer forms galleries beneath the bark, usually of Unhealthy trees, and can only be kept in check by carefully burning all infected specimens. Of late we have noticed Beech trees both in urban and suburban districts of London attacked by the Beech Coccus (Cryptococcus fagi), an insect that is alarmingly on the increase in this country. Paraffin or petroleum emulsions will destroy the insects; and scrubbing affected parts with a brush and soft soap is to be recommended.