TREES AND SHRUBS

Wairarapa Times-Age, 7 October 1938, Page 2

TREES AND SHRUBS

WHY THEY DIE BACK. Trees and shrubs sometimes produce only a small number of shoots in a season, and these are short and weak. At times they may even show actual dying back of the branches. ), Gooseberries, raspberries, apples, and currants, ornamental shrubs and trees, and even roses may be affected. Usually the leaves fall early, and in less severe cases, although the leaves last until autumn, they drop earlier than they should. Very often such defoliation in a shrub is followed by many branches dying back. Often no disease is on the branches and the trouble is due to weakness caused by unsatisfactory root action. Apart from disease in the roots and collar, there are many plants that show dieback very quickly when the root action is faulty. Cherries, lilac, flowering currants, and rambler roses will show ill-health by producing smaller pale green or yellowish leaves. Following this there may be a good deal of dying back in the younger branches. When this occurs the condition ’of the soil is almost certain to be at fault. Where the ground is unsuitable a good root system cannot be developed, and it follows that the plant cannot get enough nourishment, with the result that the shoot system is slowly starved. Food substances, if thought necessary are easily supplied by giving a light dressing of a complete mixed fertiliser, but apart from this there are other considerations, such as dryness or waterlogging. The latter is by far the most common cause of poor root action. Whichever is suspected, the remedial measures can be undertaken while the trees are dormant. In the case of soils that quickly dry out, dig in plenty of humus, such as leafmould, garden rubbish, and peat mould. This should be forked in around the roots. Where this is difficult, a little can be lightly forked in above the roots and the level of the ground raised by a covering of soil and humus-providing materials mixed. Waterlogging is likely to prove more difficult; but it is amazing how much can be done by deep digging to break up the subsoil without bringing it to the surface. During the digging, humus can be buried below the top spit. All this will improve ill-drained ground; but sometimes an attempt at a drainage system by means of ditches and pipes may have to be made, the ditches being filled with rough stones, clinkers, bundles of brushwood and branches. This, however, is not likely to be necessary in small gardens. The difficulty often is to find a natural slope oi- fall to lead away stagnant water or to find a stream or ditch for the outlet. In the absence of such amenities a soak away may be possible, and this is made by digging a hole deep enough to break the impervious subsoil and filling the hole with stones or clinkers, through which the water can percolate. In small gardens, generally speaking, most soils can be improved by deep digging and incorporating humus. Some people regard dieback of any sort to be a disease of the branches; but this is not always so. It is useless to expend money and labour on spraying branches that may be affected by poor roots. A far better plan is to improve soil conditions during fine weather in winter. If it is necessary to lift the tree or shrub, this can be done now.