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 destruction of insects is perhaps the most important matter requiring the attention of the fruit-cultivator at this year. Black-fly, green-fly, and caterpillars have all been well represented this year, and no ordinary attention has been enough to keep them from destroying young growths. Cherries are generally among the first and worst to suffer from aphis. When the shoots have made good growth, and before they are tied in to the walls, an effort should be made to keep down insects by syringing with tobacco-water. "Where there is fruit this operation is difficult to perform without doing mischief. The tops of the shoots which are to be nailed in should be handled separately, dipping the point of each in a shallow vessel of tobacco-water: tobacco-powder and soft-soap, or Gishurst Compound, are equally as good. Examine them in a day or two, and repeat the operation if life is left in any of the pests. Where trees are of full size, and little growth is required, there is not much difficulty in securing clean, healthy foliage. The tops, which are generally attacked, alone can be nipped off.
This applies to all trees which do well with spurring; and I do not know any which fail by this practice, as when one batch of blossoms-may be cut off by severity of weather, there are generally plenty to succeed them. Apples are often attacked by green-fly and American bug. The curling up of the leaves with the former renders their destruction almost impossible. Young trees suffer most from this pest; and where it can be done, hand-picking off the tops which are infested, and afterwards applying the engine with tobacco-water, and washing with clean water, seems the only method of eradicating the vermin. The white American bug, now so common, defies nearly every application while the trees are in foliage. Those which were washed with brine during the winter, and afterwards coated with a paint made with lime, soot, soft-soap, and sulphur, suffer but little during the growing season. When these remedies are well followed up, the pest becomes stamped out in time. Apricots are subject to a kind of grub which curl themselves up in the young tops of the leaves, and nothing short of hand-picking that we have seen can reach them. The shoots should be kept thin, so that when the necessary wood for next season's crops is tied in, all the foliage and fruit may have the benefit of sun and air.
Those who work on the spur system entirely must keep this same important matter in mind. Spurs can be kept as close to the walls as young shoots. Choose those next to the walls; keep them there. The same applies to Plums. Though plenty of fruit may be had on out-growing shoots, the appearance of rough spurs is objectionable, and in time the tree gets out of bearing and health. Continued stopping of gross wood which is monopolising the energies of the trees should be attended to. Most cultivators recognise the advantages of attention during the growing season, though all cannot find time to do the work. Pears are by some denuded of their growths as they grow, but we think this is opposing nature instead of assisting her; and to do justice to tree and fruit alike, we prefer going over the trees at different periods, taking off a portion of wood, always the strongest growths first. Early attention to training out the leading shoots-must not be forgotten, as they are very liable to get broken. Old trees bearing well, and making little or no growth, may be materially assisted by applications of guano-water or liquid manure from the stable or cow-yard. Peaches and Nectarines require attention often, so that they do not become matted in their growth.
The shoots should be kept very thin, and the trees syringed with tobacco-powder water: if there are no vermin, the syringing is a good preventive. It may be premature to do much thinning of fruit, but where they are very thickly set in clusters, it is no guarantee of safety to leave them to destroy each other. Leave the fruit always which are best exposed to sun and air. The largest and best-formed fruit in early stages are generally the best when ripe. Strawberries are always a temptation to birds, and netting them is the only safe remedy. The netting of all bush fruits and trees on-walls, such as Cherries, must not be overlooked. Delays in such cases are dangerous.