Small Fruits Need a Good Start in Life

New Zealand Journal of Agriculture, Volume 74, Issue 2, 15 February 1947, Page 147

Small Fruits Need a Good Start in Life

SMALL fruits can be grown successfully in New Zealand if stocks are planted in suitable sites and plantations are properly managed. Some aspects of the preparation of a site for small fruit growing are discussed in this article by J. P. Hudson, Horticulturist, Wellington, who has previously dealt with the choice of sites for raspberry growing.

'T'HE initial preparation of the ground has an important effect on the subsequent life and health of a small fruit plantation. If the area is subject to waterlogging in wet. weather, or to periodic flooding, it is folly to plant raspberries, gooseberries, or strawberries unless the land is first drained. Loganberries or black currants might succeed without the land being drained, as they are more tolerant of temporary waterlogging. ' Value of Drainage System It may be necessary to install a permanent system of drainage before an area can be considered suitable for planting small fruits, but such a system should be put in only after the question has been carefully considered. Draining is expensive and not a good investment unless the drains do all that is expected of them. When properly sited, laid, and maintained, however, a drainage system may make the difference between the success and failure of a plantation. Expert advice should always be sought before installing a system of drains to make sure that it is practicable and adequate. The system should be capable of disposing of surplus water at such a speed that the watertable never rises into the topsoil for more than a few hours at a time even in the wettest weather. It is hardly necessary to say that drains cannot work unless there is somewhere for the water to go when it reaches the outflow. Building up Humus Content In a bulletin issued 45 years ago the Department of Agriculture stated that thorough and deep ploughing was essential in preparing soil for small fruit growing, and also emphasised that a heavy dressing of well-rotted farmyard manure could profitably be worked in at the same time. That advice is still sound, except that it is doubtful whether it would be profitable to apply heavy dressings of farmyard manure now in view of the very high prices ruling for that commodity. There is, however, no doubt about the need for applying some form of humus to build up the organic content of the soil before planting small fruits. If the soil

is well drained, the next most important factor in the soil is its humus content. Time spent in growing arid turning in one or preferably more green crops will be well repaid by the more rapid establishment of the plants when they are set out. It also pays to turn in, at the same time as the green crop, stack bottom, hedge trimmings, straw, roadside mowings, gorse or broom (if not too woody), or any other organic material that can be obtained, which helps to build up a high humus content, and is much easier to work into the soil before planting than afterward. Straw, stack bottom, hay, or semi-woody material tends temporarily to lock up nitrogen in the soil; such material should therefore be strewn with about fcwt. of sulphate of ammonia for each ton of dry material before it is worked into the soil to supply sufficient nitrogen for the needs of the bacteria which cause the material to change into humus.

Care in Applying Lime

Little is known of the preferences of small fruits for acid or alkaline soils, but it is known that humus disappears more quickly in an alkaline than in an acid soil. It is also believed that raspberries and strawberries prefer a slightly acid soil, and there does not seem much point in applying lime to a small-fruit plantation unless the soil is strongly acid. An overdose of lime has been known to have a very damaging effect on raspberry plantations overseas, reducing the crop for several seasons after it has been applied.

Before planting small fruits it is advisable to have the soil tested to ascertain whether it is acid. If the soil is acid, it may be decided to apply lime, the quantity depending on the degree of acidity, as shown by the test, and on the texture of the soil. More lime is needed to produce a given effect on the acidity of a heavy clay soil than on a light sandy soil of similar acidity. In the present state of knowledge of the requirements of small fruits it seems best to bring acid soils nearly but not quite to a neutral state and to maintain them in that condition.

Cultivation can hardly be too deep in preparing a site for small fruits, provided, of course, that the layers of soil are not transposed. That limits the depth of ploughing to the depth of the topsoil, as deeper ploughing would bring subsoil to the surfacea dangerous practice unless it is' done very gradually.

It was formerly common practice to plough as deep a furrow as practicable, and then run a subsoil plough down the bottom of each furrow before the next slice was turned over. That ensured that the soil was worked as deeply as possible without bringing subsoil to the surface or burying the fertile topsoil. The practice has much to commend it, but little subsoil ploughing seems to be done now.

Fruiting Habits of Raspberries

Raspberries usually , bear their main crops on canes which grew from ground level last year and which die when they have produced their fruit.

Some varieties also produce fruit from laterals which grow in late sumimer on the most advanced new canes of the current season’s growth. Berries produced in this way are usually so large and juicy that they are hard to pick and do not travel well, and are even regarded as a nuisance by growers, many of whom make little attempt to market these fruits. Lloyd George is a variety particularly prone to that behaviour in New Zealand, though it does not fruit in that way in Britain, where the variety originated. As canes which fruit thus will not fruit again the next year, they have to be cut out in the winter and represent a loss of potential fruiting canes. The view is sometimes expressed that hard tipping of dormant canes in winter will delay the emergence from the ground of new canes in spring, thus reducing the tendency of the new canes to form fruiting laterals, as it is the most forward of these canes which fruit in that way.

Lloyd George, and some other varieties, produce fruits in a third way—on the tips of the new canes in the late autumn. In favourable seasons this crop can be appreciable, but the fruits have little flavour and are soft and juicy, difficult to pick, and bad travellers. So far as is known, autumn fruiting on the tips of new canes does not interfere seriously with the following year’s crop, and overseas these fruits, carefully picked into small chips, sometimes make handsome prices on the market as late dessert fruits. Pruning Raspberries Raspberry canes which grew last season die after bearing this season’s crop of fruits. The dead canes are

usually removed in the autumn or winter at the same time as the new canes are thinned and tipped. There is, however, much to be said for cutting out the old canes as soon as possible after the fruit has been picked, giving the new canes a better chance of ripening properly. Early pruning may also help to maintain the health of the plantation, as the young canes are less likely to be infected by diseases on the old ones.

Old canes are often cut off an inch or two above the ground, but they are very much better cut off below the surface, as the stubs of old, dead canes are known to serve as centres from which infection of cane blight (wilt) can spread.

Summer Work on Raspberries

Cane blight is one of the most serious diseases of the raspberry in New Zealand, causing canes to wilt and die, usually just before the berries ripen. The fungus can live for several seasons in the stumps of dead canes, from which infection is spread; hence the importance of the early cutting out of fruiting canes just below ground level as soon as the fruit has been picked. All prunings should be collected and burned as soon as possible after pruning.

The foundation for a first-class crop next year will be laid if, ’after th© prunings have been removed, the new canes are thoroughly sprayed with a 3-4-50 Bordeaux mixture to which has been added 21b. of lead arsenate to each 100 gallons of spray. The canes should be drenched and an endeavour made to drive the spray well down into the axils of the leaves. A reasonable control of raspberry bud moth and cane spot on the young canes should be obtained by prompt removal of diseased and old canes and by the spray application after harvesting.

Pruning Black Currants

Black currants will bear fruit next season on the new shoots which nave grown this year. Pruning should therefore consist of removing each year, after the fruit has been picked, as much as possible of the wood , which has borne fruit, leaving the new shoots which have grown this year to bear next season’s fruit. If pruning is done as soon as the last of the fruit has been picked, the new growths will have a better chance of ripening before the winter.

CULTURE OF SMALL FRUITS

Cutting out the shoots which have just fruited involves some sacrifice of new growths, as each branch cut off will have a new shoot at its end. That cannot be helped, and is necessary if the bush is to be kept fruitful.

Very thin new shoots should also, be removed, as well as branches which cross or hang too low on the outside of the bushes, or are damaged. ' Old, neglected black currant bushes present a pruning problem. There are probably few new growths, and those which do exist are usually borne high up on the bush. If the bushes are more than 10 years old, trying to bring them back into production is probably not worth while. They should be grubbed out and replaced. If the bushes

are worth saving, but are suffering from lack of proper attention to prunin S> the best plan is to cut about twothirds of the branches to within a few inches Qf the ground . This sacrific es mO st of the crop which would have been produced next year, but should ensure that the bushes produce ample new shoots, arising from near the base, o fruit in ’ the following season. The j d branches which are left. this year should be cut back to ground level next year.