Much thought has gone into shelter for new orchard

Press, 30 October 1981, Page 16

Much thought has gone into shelter for new orchard

By

DERRICK ROONEY

Shelter planting, and its necessity on even the smallest property, was the theme of a recent field day held by the Central Farm Forestry Association on small holdings in the Prebbleton area.

During the morning the farty visited the property at rebbleton where Mr W. Mottram is establishing a new orchard of both pip and stone-fruit trees.

Considerable thought has been given to the planning of shelter on this property, and all plantings — both the orchard trees and the shelter belts — have been kept clear of weeds, mulched with plastic, and trickle irrigated. The value of. this extra management became clear

when it was. seen that some of the hedges of Salix matsudana — a willow species popular in the North Island but not yet widely planted in the South Island — had reached a height of 2m two years after being planted as cuttings.

Mr Mottram told the party that meteorological data obtained before any plantings were planned had shown the north-east and south-west winds to be the main problems, but after work had begun on the site it became clear that the nor'wester was a serious problem, though its frequency was not high, it tended to be a very strong and gusty wind capable of doing, considerable damage.

A lot of Lombardy poplar has been used in Mr Mottram’s external shelter belts for a variety of reasons. One was that plenty of cuttings were available from the shelter belts around Mr Mottram’s existing orchard, and this meant that the best type of cutting could be selected. Also the Lombardy poplar provided good high shelter without side trimming. Rust was a problem, but a minor one in Mr Mottram’s opinion; while the trees are young he is spraying them twice during the’ growing season with a copper fungicide to control the'rust, but he believes that

once they have matured the trees will cope without spraying. He believes, too. that he will be able to discontinue trickle irrigation in a few years, by which time the trees should have sent their, roots well down into the freely drained soil. Ultimately the trickle irrigation will be discontinued from the fruit trees also, and will be replaced by a system of overhead sprayers, which will double as frost protection on risky nights in the spring.

Members of the party expressed interest in the training method being used on Mr Mottram’s young apple trees, which are being taken up in tiers to. an ultimate height of about 4m, producing narrow pyramid-shaped trees that produce the maximum .crop on the minimum of ground space and cast the minimum of shade on their neighbours. The fruiting branches are being trained in cross-shaped tiers, as near to the ideal crotch angle of 60 degrees as possible, and where necessary are being tied down to achieve this. Each tree will, probably have four tiers of branches. Not only does this system make efficient use of

the ground space — it produces a tree from which the fruit is very easily picked, unlike the old vase-shaped type of fruit tree.

On Mr Mottram’s property the party saw a dramatic example of the influence that shelter can exert even on a shelter-belt planting. In. a row of Lombardy poplars, all planted at the same time, at the same size, and given the same irrigation and fertilising regimen, one group of trees was significantly taller than the rest of the row. The reason for this, quickly spotted by the members of the party, was the moderating influence of a large old macrocarpa hedge to the northeast,, across the road on a neighbouring property. The party also took a close interest in the plantings of stone fruit — nectarines and peaches — in which pruning has been minimal. Mr Mottram explained that modern thinking on nectarines was to regard them as a short-term crop, with a life-span of perhaps eight years, and to encourage them to fruit at a very young age. Early fruiting, plus the very light pruning, inhibited the growth, producing smaller and more easily managed trees. After eight to 10 years; though, the trees began to get too big. The party also, visited a

property in Trices Road on which Dr R. A. French and his wife run stud sheep, deer, horses, and poultry. Though this was only a few kilometres from Mr Mottram’s property, it presented very different management problems, because of a clay pan 45cm below the soil surface, and a high water table. Here again, poplars (a hybrid Italian variety) provided the main shelter from the north-easterly wind, and a row of old pine’s and macrocarpas gave some north-west shelter.’

Establishment of the poplar shelter had been difficult. because though the soil could — and often did — become waterlogged at wetter times of the year, drought in summer was a problem, especially when combined with the prevailing north-east wind.

Two early attempts to establish • poplars failed. Dr French told the party. But the existing planting, now eight years old, had been successful, and was now providing good high shelter.

Much of the discussion .at Dr French’s property centred on a small, experimental planting of tree lucerne. Various aspects of this crop were discussed, and various methods of managing it were proposed, but the consensus seemed to be that if the right management procedures cbuld be found, this plant could have a bright future as a fodder crop in much of Canterbury — a frost barrier might inhibit its widespread use in the colder inland areas. :

Dr French’s seedlings were sown in September of last year, and reached a height of 50cm by the end of summer. In April he harvested the green matter, cutting the plants down to 23cm. This produced 1.275 kg of dry matter from a 2.1 m row of seven plants, spaced 30cm apart, and Dr French calculated that this represented a yield of 6000 kg of dry matter to the hectare from plants in rows spaced Im apart. But he expressed doubts about whether this type of close cropping and hard, pruning could :be sustained by the tree lucerne plant, and several members of the party agreed with him. There was general agreement, though, that properly managed tree lucerne has a strong, future as a fodder crop. It is regarded as -particularly suitable for deer, and one member of the party described an Australian management technique in which the plants are grown between two netting fences, 2m high, so that livestock can keep them trimmed by browsing off the branches that grow through the netting. The young growths are said to be very palatable to stock, and to make an excellent internal shelter. But it was clear from comments made that much remains to be learned about the tree lucerne, its' palatability, its nutritional value, its tolerance of frost and drought, and its sensitivity to overwatering.