SHELTER-BELTS.

New Zealand Journal of Agriculture, Volume XVIII, Issue 3, 20 March 1919, Page 165

SHELTER-BELTS.

REQUIREMENTS FOR THE ORCHARD.

By

W. H. TAYLOR,

Horticulturist.

There can be no' doubt that in the past the planting of shelter-belts in New Zealand has mainly gone along two lines, one being the factor of quick growth, the other as to what trees could ' be obtained. Quickness of growth is likely to be always a chief factor. It will be a mischievous one or not according to the view taken of what constitutes quick growth (this being capable of various interpretations) and to the purpose of the belt. Regarding the latter consideration, a tree or collection of trees that would be quite adequate for farm shelter might be quite inadequate for orchard she'ter. As to the first consideration, an illustration of my meaning may be given. Pine-trees are, I believe, planted in greater numbers than any other species. It is inevitable that the lower branches die, thus leaving the lower portion of the trunks bare. The pine.-trees mostly planted are P. insignis (properly radiata) and P. muricata. . ‘ The insignis loses its lower branches at an earlier period than does the muricata. The distance apart the trees are planted has its effect — closer they are the sooner the lower branches die. The trees are usually planted .rather close together, otherwise they would provide no shelter for many years. While the trees are.young they make good shelter, but when the lower branches are gone the wind goes through and creates a draught, which in its immediate neighbourhood is worse than uninterrupted wind. If the purpose of the belt was to give close shelter it may have done so for a time, but the eventual condition is worse than no shelter. How, then, can it be called quick growth, when it' ended in nothing or- worse than nothing ? Such a plantation, however, might be quite; sufficient on a farm where breaking the force of gales of wind and providing, some shade are the primary objects. . In such case the term “ quick growth ” is applicable. - Pine-trees: will continue to be employed in shelter-belts, and rightly,. so, but where close shelter is required there should be an outer row of some other tree or shrub. ' . ' ' ' ;

One of the requirements of the present time is shelter for orchards. Where the acreage is small the width of shelter-belts must not be great —the narrower the better, provided they be ■ effective. The cost of maintenance should also be considered. If trees or hedges that need much trimming .be planted they are sure to be more or . less neglected, for an orchardist can seldom find time for such work; ■ therefore such trees or hedges should not be planted. . :

Climate is another factor to be reckoned with. Some trees that do well in the north will not survive in the climate of the. south.. In the Waikato and about Tauranga the black-wattle (Acacia .decurrens)

is doing well. The belts on the Te Kauwhata Horticultural Station appear . quite ' effective. At Tauranga they are even better, looking more flourishing. On the Tauranga Horticultural Station there is a belt about 15 ft. wide, with trees about 4 ft. apart. The seeds were put in five years ago, and the trees average from 30 ft. to 40 ft. in height. This is surely as quick growth as can be desired. The estate of Messrs. Mayfield and Chaytor, a little way out of Tauranga, where 75 acres are planted in orchard, is divided into blocks with narrow belts of the black-wattle. The trees in all the belts look very s leafy and flourishing, and are answering' their purpose very well indeed. Wattle plantations are established by seeding; the trees do not transplant .’well. It is the habit of the wattle to lose its bottom branches, and although this state can be postponed by pruning it is advisable, if not necessary, to plant a line of some tree or shrub on the outside that will retain its lower growths. This is necessary where the wind is very , strong. The wattle is not very amenable to heading back ; -it cannot be relied on to break out again if cut back to bare wood, but shortening of branches can be done with good effect, provided some active growth is left below the cut.. It would seem wise to extend the planting of wattles in northern districts. The cost of upkeep is trifling once the trees , are established ; lopping off branches where it is thought necessary is easily done, and all the wood is useful, even quite small branches making excellent, firewood. Silver-wattle (Acacia dealbata) must not be planted, because it suckers badly nor blackwood (A. melanoxyldri), this being too slow in growth, though eventually making a good dense tree.

Where a h : gh or moderately high shelter is required, and it is desired to keep it to narrow limits, the. Lombardy poplar is, I believe, the best tree to plant. The trees require topping occasionally, but .it is not an expensive operation, the wood being soft and easily cut.. The objection may be raised that the wood is useless ; but, while it is certainly less valuable than most wood, it makes firewood that many people , are glad to use. In Hawke’s Bay, where the tree is extensively grown, the wood is so used. It is also often used as fence-droppers. These last at least a few years, and they are easily split out of the green timber. A number of orchards in Hawke’s Bay have a single line of poplars as shelter ; in some instances the trees stand 2 ft. apart, in others at a greater distance usually cuttings are planted. Some of these -belts have a hedge of common barberry on the boundary side. A single line of Lombardy poplar makes a cheap and effective divisional shelter inside an orchard where the extent of the latter, or the climate, makes it necessary to supplement the belt on the boundary. So far as I have seen and heard, this poplar does not sucker to any extent, the suckers being . restricted to roots near the surface, which will not exist in a well-kept orchard.

I consider that a combination of Lombardy poplar and Elaeagnus japonica will make the very best shelter-belt of the narrow order it is possible to obtain. Some years ago a combination belt of this kind was planted on one. of the Department’s farms. The poplar cuttings were planted in two rows 5 ft. apart, and about 3 ft. apart in the rows. The elaeagnus plants were put in 30 in. apart along the centre between the rows of poplars. Unfortunately there came a change in authority, and the elaeagnus was ordered to quit. In the meantime a mat of Poa pratensis had formed, which made the digging-out of the elaeagnus a fairly

heavy task. The plants were therefore removed with an adze,- cutting the stems as .low as possible. After this treatment, and notwithstanding the couch-grass, many of the plants made new growth, and. they are to-day climbing many feet high in the poplars, the two forming at these places a fine shelter-belt. Had the plants been left as put in, the result would have been a barrier able to defy man or beast, and a first-class wind-break. In such position very little trimming would be required at any time, and the character of the growth would absorb the wind rather than drive it over the top, as often occurs with closely .trimmed hedges and even with, trees of a ' dense habit of growth. As indicated, I am of opinion that this combination is the best possible where the wind is very strong, and where an effective barrier is required to keep out intruders, either two-footed or four-footed.

A belt of this kind, however, would not suit the taste of every one) and that perhaps is fortunate, as from an aesthetic point of view some diversity in form of tree-growth is desirable, otherwise the landscape would have a monotous appearance. When planting is being planned the habits of the trees should be considered in relation to the space they are to cover, their capabilities for providing shelter, and the demand they would in future years make on labour to keep them within proper limits. In all cases the less trimming that is required the better, not alone as saving labour but also because the more a tree can be allowed to keep its natural habit the more beautiful it is. For this reason large trees, such as Pinus insignis and Cupressus macrocarpa, should not find a p'ace in narrow belts. If they are allowed to grow unchecked they smother everything else, or occupy too much space, and if they are checked much labour -is involved. Almost any other pine is better, with the exception, possibly, of a very few, such as Pinus sabiana and Pinus Lambertianq, which, being loosely clad with foliage, would not give good shelter. Pinus muricata is, I think deservedly, most valued for shelter-planting. It is a dense tree, eventually round-headed, and not inclined to be overpowering. It is also hardy in most parts, and is perhaps the best pine for planting near the sea-coast.

In inland - positions there are many suitable trees the inclusion of which would add interest and beauty to a belt,, and this might well be considered and acted on when the same result as to shelter, the primary object, can be secured. The redwood of California {Sequoia sempervirens} should also find a place. . This tree is not wide-spreading, and retains its lower branches, as is usual 'with trees of pyramidal habit. Cupressus torolosa, Cupressus Knightii (with glaucous foliage), and Cupressus Goveniana are admissible. Acacia decurrens var. mollissima dotted here and there would add colour and brightness. A few deciduous trees of quick growth, particularly sycamore and planes, might be included. When there is a desire to keep out wind or to secure privacy, an outer row of a special character should be planted. What this is to be may be a matter of individual taste. . Lawson's cypress— Chamaecyparis [Cupressus) Lawsoniana — stands out beyond all other trees for this purpose, being the hardiest evergreen tree we have, quite indifferent to wind, dense in habit, always clothed with branches right to the ground, and fairly fast in growth after the first few years. ■ This tree does well planted at any reasonable distance apart—from as close as 12 in. for a pure hedge. For the shelter-belt purpose now under consideration

the plants would soon close up if put in 4 ft. apart; while if the distance was increased to 6 ft. or 8 ft. they would take longer to close up, but. would do so eventually and make stronger trees ’than those planted closer. Retina sp or a plumosa bears wind well and thrives in dry soil; it also grows fairly fast, but hardly so fast as Lawson’s cypress. Retinospora is also hardy, bears drought well, and is rather more rapid in growth than Retinospora plumosa. The cypress formerly known as Torolosa elegans, now as Cupressus slogans, is a tree that furnishes well and never, requires clipping. These trees are well adapted for dotting in a line of Lawsoniana to break the monotony.

Should the belt be intended for orchard-shelter an inner row of a hedge-like tree is not necessary if the outer line of trees has been well chosen, and, as the shade of the trees makes a good packing-place in dry weather, there should be free access to it. For. ornamental purposes a hedge inside may be advisable, or it may be planted up with various small-growing trees and shrubs. Reverting to the outer line, it may be decided to plant something in the nature of a hedge. If this is done the nature of the plant used in relation to labour in trimming should be considered as previously discussed, and this is a matter the owner should decide. The African boxthorn (Lycium horridum) has a habit of growth that renders clipping unnecessary if -height is not objected to, and might be planted instead of Lawson’s cypress. It makes an impassable barrier and good wind-break, reaching a height of nearly 20 ft. The plants should be cut down to about 6 in. from the ground a year after planting; they then shoot up straight and need not be cut again. Elaeagnus would not answer so well in such a position, though it is dense-growing and hardy, as it requires a lot of trimming and is not a good thing to cut.

In the growing of shelter-belts practice shows that planting almost any reasonable distance apart answers, with the exception that if very fast-growing trees are planted near others of slower growth the slower subjects will be overgrown. For this reason wattles should not be planted close to pines, as the pines would be smothered. If pines are expected to preserve their natural form they need to be 20 ft. or more apart. I do not think that desirable for the shelter of small properties, but would prefer to have two rows rather than 7 one row, the two only, to occupy the space that one row could fill. As previously mentioned, the lower shelter should be provided for b’y an outside line of suitable character. The chief thing to consider, therefore, is the higher shelter. Pine-trees are for a number of years pyramidal in habit; some of them change later to round-headed trees, but in the first instance they are all alike. It is thus evident that for many years wind will .have a free course between the heads of a single line. This is why it is preferable to plant two or more rows, as if planted in quincunx order the trees would make a perfect breakwind in a much shorter time than would a single row, the heads of one row closing the intervals in the other row or rows. It is known that. pines do well planted as close as 30 in. apart. They quickly lose all but the top branches, but the tops remain in good condition an unknown number of years. In general, however, from 6 ft. to 8 ft. are good distances to plant. I would prefer three rows 6 ft. apart to two rows 8 ft. or more apart. Such a belt .would provide good orchard-shelter ; it would be best to plant it entirely with pines.