THE FRUIT SECTION.

New Zealand Herald, Volume LXIII, Issue 19384, 20 July 1926, Page 16

THE FRUIT SECTION.

SPRAYING FRUIT TREES, BY S.T.R. Last week a general survey of the common sprays was given, which will greatly help my readers in understanding the following notes. As many amateur gardeners are not able to recognise the different diseases they have not been able to proceed with their spraying operations; the following details regarding the spiaj ing of fruit will, I hope, assist them. Spraying the Peach. With the peach tree are included the nectarine, apricot and almond. These trees are subject to several fungoid diseases and insect pests. Of the former, brown rot, leaf curl, silver blight and shot hole fungus are the commonest. The most important insect pest that attacks t e peach is the mussel scale. Brown rot appears as little brown spots, which increase in size very rapidly in. humid conditions. It develops into a rot covered with a grey mould. This disease winters m a form that is inc.estructible by ordinary methods, therefore, it should be destroyed before it.assumes this form. To effect this, spray with copper sulphate solution in early autumn. The only control measures that can be taken a* present are to destroy, by burning, all mummified, shrivelled fruits that may happen to be on the trees. Leaf curl attacks chiefly the leaves of the tree, although the flowers and fruits are also sometimes affected. Affected leaves are discoloured and malformed. From a reddish tinge they change to a pale colour. They also swell up considerably and make the leaf very crinkled. The leaves fall off, but the second crop of leaves, which develop to take the place of the fallen leaves, are usually immune. The loss in leaves temporarily checks the development of the fruit, as a result of which the fruits are stunted. Treatment of this disease consists of spraying with Bordeaux, at the winter strength of 4-4-40, just prior to the opening of the buds. If the young foliage should happen to be affected spray with lime sulphur at a strength of 1 in 100. Shot hole fungus occurs as small pale spots on the leaves. The spots turn brown and drop out, leaving a circular hole like a shot hole, from which it has received its name. The spots drop out as a result of the supply of food being cut off by a ring of corky material forming around the spot, causing it to wither and die. The damage to the leaves caused by this disease stunts the fruit. To control the peat dig over the ground around the trees to bury the rings that have dropped out of thb leaves as they are a source of infection. Spraying measures should consist of an application of lime sulphur (1 in 100), before the foliage is quite half-grown. The mussel scale is not often found on peaches. Its first preference is the apple. It is a small brown "scale resembling a mussel shell in shape. They shelter a number of eggs, which hatch when the warm spring weather comes. The young larvae suck the sap through the bark and in a few days change to the pupa stage. The pupae shelter under the scales and pass the winter. To check this pest spray now with red oil emulsion. Spray with kerosene emulsion later on when the foliage develops. Treating the Apple. The chief diseases which infect the apple tree are black spot and silver blight. Black spot occurs as dark green patches on the leaves and fruit, and sometimes on the yeung twigs during the early part of the vegetative season. As the season progresses these spots change to«brownish scabs, which may be cracked. The fallen leaves harbour dormant spores, which will infect the tree next year, therefore all leaves should be gathered up and burnt, or else dug Under. Spray the trees just when the buds turn pink with Bordeaux 4-4-40. If this spraying does not ' prove totally effective and the disease has infected the younger foliage spray with Bordeaux 8-8-40, when the fruit has set. Although little can be done when silver blight has got a hold of the tree in the way of spraying, a top-clressing of from 41b. to 81b. of sulphate of ammonia to each tree in early spring is beneficial. An alternative manure, but also effective in helping to throw off this disease, is sulphate of iron, applied • in a pulverised state at the rate of 81b. to 101b. to a tree. Combating Insect Pests. The apple is affected more by insect pests, chief among which are the codlin moth, woolly aphis and mussel scale. The codlin moth is of a greyish-brown colour about half an inch long. The moth lays eggs oil the fruit, or even on the foliage. The grubs, which hatch in about nine days' time, burrow into the core of the apple, usually at the end farthest from the Btalk. As the grub destroys the core the fruit often falls to the ground. This insect is controlled by a triple spraying of arsenate of lead. The first spraying takes place within five days of the falling of the petals. The second should be given between the fourth and sixth weeks after the fall of the petals, and the final spraying about the tenth week after the dropping of the petals. Woolly aphis is well known because of the white woolly fluff which the aphides carry on their backs. They cause what are known as galls on the twigs, and generally reduce the vigour of the tree, "his insect is controlled by winter spraying with red oil emulsion, and, if necessary, a . 'summer spraying of red oil emulsion, keirosene emulsion or tobacco wash. In my personal experience I have found that by dabbing JBiected branches and twigs with kwo£e"e. <hls P es t was effectively controlled. ihe treatment of mussel scale has been dealt with, but it might be added that, as the apple is the favourite host plant, the insects will be more numerous and consequently spraying should be more thorough. The Pear and Plum. The pear is subject to woolly aphis and codhn moth, though to a lesser .degree than the apple, and also the mussel scale. It iis also subject to the ravages of the ! p6ar and cherry slug. There is no winter treatment for this, latter pest, but in summer the trees are sprayed with arsenate of lead whenever tlie green slimy larvae are noticed. The main fungoid disease that attacks the pear is the black spot, of the apple The plum is open to the attack of the mussel scale and occasionally to the ravages o£ the codlin moth, but in the latter instance there must be a scarcity of the more favourable host plants. The fungoid diseases which attack, the plum are shot-hole fungus, brown rot, siiver blight and powdery mildew. The latter is distinguished by a powdery substance on the leaves, and is sprayed in summer • with summer strength of Bordeaux (8-8-40). Citrus Trees. Citrus trees are very subject to the attacks of aphides and other insects. To combat, these spray with red oil emulsion. Verrucosis is sometimes troublesome, on lemons and should be sprayed with Bordeaux afc a strength of 8-8-40 daring August.