THE ORCHARD.

New Zealand Journal of Agriculture, Volume 43, Issue 3, 21 September 1931, Page 216

THE ORCHARD.

Spraying Points.

During October spraying for the control of diseases should take precedence over all other activities in the orchard. The germination of fungus spores will be taking place rapidly under the influences of rising temperatures and atmospheric humidity, and young fruit will become exposed and develop rapidly in size, thereby increasing the field of infection. It should be borne in mind that the end of this month, generally speaking, terminates the period during which the more concentrated spray-solutions can be applied with safety, and that the maintenance of the orchard free from infection by fungus diseases at the commencement of the season has a valuable influence up to the close of the growing-period. This statement also applies

to the control of those insect pests the broods of which come forward in the early part of the season. “ Prevention of increase and limitation of distribution ” should be the slogan of all commercial fruitgrowers, this referring particularly to red-mite and apple-leaf hopper, both of these insects appearing as nature provides the foliage for their sustenance.

Last month’s notes dealt with suitable spray programmes for the control of the principal diseases and pests, but a special reference to apple-leaf hopper is timely. For the information of readers whose orchards are subject to infestations of this insect it may be mentioned that at the nymph stage the activity of the insect is much restricted, and in consequence control is more easily effected. An application of emulsified oil 1-150 plus Black Leaf 40 1-800 will give a 100-per-cent. kill of those insects which come into actual contact with the solution. Thorough application of the spray, so that the under-surface of all foliage is wetted and no detail is missed, makes this possible.

Fireblight.

Careful watch in both infested and non-infested areas for the occurrence of this bacterial disease is a duty on the part of all orchardists in the interests of themselves and the industry as a whole. Primary infection becomes obvious with the blackening and withering of the blossoms, and later results of infection may be observed by the oozing of sap from the cankers following the breaking-down of wood tissues in the limbs of the trees. The only means recognized as providing satisfactory control is that of cutting, away (well outside the area infected) and destroying by burning all diseased parts. The diseased part of the tree is defined by discoloration of the cambium layers. In cases of tip or blossom infection removal should take place at least 6 in. below discoloured tissue, and in the case of large cankers on the main branches removal of the entire limb can be recommended. This somewhat drastic precaution is desirable in order to avoid the retention of infected surfaces over which ooze may have passed and which has become unnoticeable .by drying off.

In addition to attention to the fruit-trees, it is of vital importance, to fruitgrowers that, all hawthorn growing in the vicinity should be kept under observation. Flowers should be closely examined during the blossoming period, bearing in mind that infection in the first instance may be comparatively localized, and that it is within the range of possibility to stamp out initial outbreaks of the disease.

Thinning of Fruit.

This work is of great value in the elimination of disease-infected fruit, together with regulation of the size of fruit and quantity of crop. The results of systematic thinning are far-reaching, not only improving the crop for the current season, but determining in most instances the growth of the tree and subsequent development of the fruit-buds for the succeeding year. It is not always an economic proposition to thin large stone-fruit trees, and such being the case severe cutting-out of fruiting l , wood during the dormant season should be resorted to, especially in the case of peaches, nectarines, and Japanese plums. Heavy cutting-out of fruiting wood may appear a sacrifice at the time, but it is" in most cases a really good investment in fruiting wood for the following season.

In thinning apples and pears, growers must be guided by the general condition of the trees. Robust trees likely to maintain their growth and size of fruit may be left with three fruits to the cluster ; others with less constitution should be thinned to two or even one fruit, according to vigour and variety. Generally short-stemmed spur-bearing varieties require more drastic thinning than long-stemmed lateral-bearing varieties, having in mind that opening-up of the clusters restricts the shelter and security afforded such insects as bronze-beetle and leaf-roller caterpillar.

Care of Grafts.

Results of reworking will become apparent towards ■ the end of this month. Where failures have occurred it is not too late to retrieve the position by an addition of more scions, provided the wood has been kept dormant by complete burial in damp sand and stored in a cool place. Growth which arises from the cut-back branches should not be entirely removed until the following dormant pruning, pinching only being practised where the growth is likely to submerge the scions. Growths arising from the stocks have a definite value in the maintenance of excitement to the roots.

Cultivation.

The harrows should now be used to conserve all moisture obtained from the spring rains and to kill weed seedlings. In heavy soils this work is best carried out when the soil is damp but not wet. —M. Davey, Orchard Instructor, Mapua.

Citrus-culture.

The principal work for the coming month will consist of pruning all trees. This should be specially directed towards the removal of all dead or worn-out wood. It is very necessary that particular attention be given to the centre of the tree. All growths should be well regulated, otherwise a large portion of the fruiting-area may be lost. Cutting back all exhausted wood to a. sound bud will give replacements of fruiting laterals. In this manner the crop can be considerably increased. This applies only to lemons, which carry their fruit throughout the tree : it does not apply to oranges with the fruit on the fringe extensions. Citrus trees have naturally a shallow-rooting habit, but cultivating to a fair depth will assist towards forcing these rootlets to a greater depth where more moisture can be obtained during seasons of limited rainfall. This is of some importance, otherwise wilting of the leaves or partial defoliation of the trees may occur, and thereby cause a loss in the succeeding season’s crop. Ploughing should be completed before the surface dries out, otherwise the trees may be checked by disturbing or exposing the roots. Moreover, should a green crop have been grown it will be in a good condition to turn under, and should there be a growth of weeds they can also be buried. If the soil is in a clean condition ploughing at this period of the year is always beneficial, as it breaks up the compacted soil and thereby permits aeration. Ploughing should not be done too close up to the trees, as it may destroy a large quantity of useful roots. ■ The whole of the cultivation 4 of citrus orchards should be carried out with a certain amount of methodeach seasonal operation as it is required. The small portion of ground near the trees should receive attention with hand implements, ■ but. the area need not be large so long as the right implements are being used for the general cultural practices.

L. Paynter,

, Orchard Instructor, Auckland.