This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
The planting of the Currant is accomplished exactly in the way that has been recommended for the Gooseberry, and the general training and after-management are much the same in ordinary cases. "Where, however, the largest and finest fruit are desired, they ought to be planted against a wall, and the wall having a southern or western aspect will be found to be the best. According to the height of the wall will in a measure depend the form of training to be adopted. If the wall be under 6 feet in height, one plant every 2½ feet will be sufficient to plant; if over this height, one plant will be necessary every foot. From the plant upon a wall under 6 feet in height must be trained three branches, one running straight up from the stem, and one on either side at a distance of 10 inches, also running up in a straight line towards the top of the wall. In the other case one straight stem is carried up from the plant to the top of the wall, but in both cases it is necessary to cut back the branches at every pruning season to such a length as shall be deemed necessary in order that there may be plenty of fruit-bearing spurs left all along the branch from top to bottom.
By this means a wall can be filled up in a very short space of time, not only with wood and leaves, but also by a regular set of fruit-bearing trees, which will repay much earlier than anything else the labour that has been expended upon them.
Where walls cannot be spared for this purpose, the next best method is as follows. As soon as the young bush has formed its first set of branches, let these, whatever their number be, whether four, five, or six, be trained up to a set of stakes or to a hoop. They should be so placed that at 1 foot from the stem each shoot ought to be 6 clear inches from its next. As they grow larger, hoops may be used, and the branches allowed to become from 9 to 12 inches apart. Year by year larger hoops must be used until the bush has become thoroughly filled up with a nice set of fruit-bearing branches having a diameter of about 4 feet. No branches should be allowed in the centre, except in the case where variety of training may be desired, and in such case only one stem trained to a centre stake is admissible. We know of no method, except on a wall, where such fine fruit can be obtained as by the one just described. By this method every branch is open and free to the influences of the sun and air, and, as a consequence, every encouragement is given for the production of large, well-flavoured fruit.
A little more distance plant from plant may be necessary than in the ordinary modes of training, which may be the same as the Gooseberry, but as a rule, 6 feet plant from plant will be found to be quite sufficient.
A few words regarding the pruning of the Black Currant will be sufficient. The pruning of these differs from that of other Currants in this respect, that Red and White Currants are done upon the spur system, much similar to that generally practised upon Vines, whereas the pruning of the Black is more of a thinning nature, much after the style of Peach-pruning. In fact, from the nature of the Black Currant, all that is necessary is to thin out regularly all the old exhausted wood, and encourage the formation of new healthy shoots as "far back" as possible. By regularly attending to this, old bushes may be kept bearing for thirty or forty years, and the fruit produced from such bushes is often of a quality superior to that produced by younger plants. The planting and early management of the Black Currant are the same as the Red - the Black, however, delighting in a soil of a rather heavy nature.
The diseases to which the Currant is liable are canker, and a sudden dying-away of some of the branches during the summer season. The cause of canker in the Currant arises from the same causes as those which cause it in other fruits. As prevention is better than cure, the best plan is to cultivate the plants well, and plant them in the soil which is best suited for them. If this be done, there is not much reason to fear from either of the above-named diseases. There is a disease which has made its appearance upon Black Currants in many places within the last few years. It is apparently very fatal, but as it has never made its appearance among any plants under my care, and as I know very little about it, in the mean time I had better refrain from making any remarks regarding it.
The insect enemies are, in many cases, the same as those which attack the Gooseberry, and such being the case, we beg to refer the reader to our last article, where he will find them described. Besides the three there mentioned, there are first the Tinea capitella, or triple-spotted Currant-moth. The larva attacks and feeds upon the interior of the young wood, and so great at times is their destruction that bushes are almost entirely destroyed by them ere the month of June. As soon as the enemy is noticed, all affected branches ought to be destroyed by burning them in the furnace of soma of the forcing-houses.
The aegeria tipuliformis or Currant sphynx-moth is another great enemy to the Currant, especially the Black Currant. Its presence is indicated by the withering of the leaves and branches. Wherever its presence is noticed, the branches ought to be removed and burned as in the former case. In the month of June the female deposits her eggs in the joints of the branches, and more especially the younger branches or twigs. The larva, as soon as hatched, penetrates to and feeds upon the pith until it has attained its full size, after which it changes into a pupa, having short sawlike spines, by means of which it is enabled to ascend to an orifice prepared by the larva upon the side of the shoot from whence escapes the perfect moth. Aphides are often very troublesome in summer, but as we have so often referred to them in previous papers, there is no need to describe over again what we have before said. With regard to red-spider the same may be also remarked. James M'Millan.
(To be continued).