In the Orchard and Vineyard

New Zealand Journal of Agriculture, Volume 63, Issue 4, 15 October 1941, Page 337

In the Orchard and Vineyard

Orchard Notes

Spraying of Apples and Stone Fruits

TIE principal pests and diseases to be watched for during the month will be black-spot, codling moth, powdery mildew, leaf hopper, red mite, and bronze beetle, and the spraying schedule as recommended in last month’s “Journal” will be found suitable for control. Complete coverage, adequate equipment, proper materials, and correct times of application are essentials to success. As the blossoming > periods finish, spraying operations take on a different aspect. Up to the present only single sprays have been necessary either to combat insect pests or prevent fungus diseases. Future sprays will mainly consist of several different materials in combination for the control of both insect pests and fungus diseases, and care must be taken in the selection and strength of such materials in order that no damage may be caused to either fruit or foliage. At this period. fruit is very susceptible to injury, and russeting is liable to occur should wrong materials or strengths be applied. Trees which may be in a weakened condition through overcropping or lack of attention are more easily damaged by spray mixtures, and - precautions should therefore be taken. . With most varieties of apples a combination of lime sulphur at a strength of 1:150 and colloidal sulphur at a strength of 2:100 will be found effective for the control of fungus diseases. This spray also has the advantage of assisting in keeping red mite in check by destroying many of the -hatched insects and thus keeping the trees fairly free from this pest until it is necessary to apply summer oil. Lime sulphur is more effective as a fungicide when used in combination with colloidal sulphur than when used alone. The use of colloidal sulphur alone on varieties known to be susceptible to spray injury and russet is recommended from the blossoming period onwards. Codling Moth Spraying for the control of codling moth is recommended from the petal stage onwards. An earlier spray than usually applied is advisable. The addition of 3 lb of hydrated lime to every 1| lb of lead arsenate per 100 gallons of water is recommended as a safe-

guard against foliage injury, especially in cases where the water used is inclined to be hard. If the lead arsenate and Bordeaux mixture combination is used it will not be necessary to add the extra hydrated lime, as there will be sufficient lime present in the Bordeaux mixture if prepared as recommended. Lime sulphur 1:150, plus colloidal sulphur 2:100, plus lead arsenate la: 100, plus hydrated lime 3:100, if applied thoroughly, will materially help in the control of fungus diseases as well as reduce risks of codling moth infection. Another application, using the same formula, should be applied from ten to twelve days later. Bronze Beetle This pest causes considerable damage to fruit in the young stage by chewing the surface of the apple, and often makes it unsaleable. , Clean cultivation, especially around the trees, is one of the best means of control, and spraying with lead arsenate will also be effective in resisting attacks. Applications must be thorough. Apple Leaf Hopper Apple leaf hopper causes considerable damage to the foliage of apple trees, especially during dry seasons, and if nothing is done for its control the fruit will be considerably disfigured by the excreta of the insects. Hoppers usually appear soon after the trees come into foliage, and the addition of nicotine sulphate at a strength of 1:800' at this period while the insects are in the nymph stage is recommended. If they are left until the winged stage is reached, control will be increasingly difficult. Should nicotine sulphate be used alone, better results will be optained by the use of an activator. Spraying for Pears The use of Bordeaux mixture is not recommended on tender-skinned varieties of pears, such as Winter Cole and Josephine, after the blossoming period because of the possibility of russet and -skin injury, which detracts from the general appearance of the fruit. For such varieties the sprays recommended for apples can be applied with safety. Climatic conditions in some districts may make it necessary to use Bordeaux mixture for the prevention of

' black-spot on other varieties, especially where control has not been obtained from the base sprays. Bordeaux mixture at strength l|:3:100 will be found ( quite as effective as a stronger solution, with less chance of russeting, and the addition of lead arsenate at strength 1J:1OO will keep a good check on codling moth infection. Pear trees are usually larger than apple trees, and every effort should be made for a complete coverage. Spraying of Stone Fruits Control of brown rot under certain climatic conditions is difficult, especially where there has been a "severe attack the previous season or where blossoming infection has not been controlled. Sulphur sprays are the only sprays recommended from this period onwards for the control of brown rot, and it may be necessary to repeat the application at three-weekly intervals up to the time of harvesting. For peaches, nectarines, and plums, lime sulphur at a strength of 1:180, with the addition of colloidal sulphur at a strength of 2:100, is recommended as a control. The same spray will also help in the prevention of leaf rust and in other fungus diseases affecting stone fruit-trees. Both black and green aphis may appear at any time as the season advances, and - spraying for control should be attended to as soon as they are seen; otherwise, the foliage will be so deformed that it will not be possible for the spray to penetrate into the colonies of ' aphis. . Summer oil at a strength of 1:100 or nicotine sulphate at a strength of 1:800 will cope with these pests very effectively, provided all the colonies of aphis are thoroughly sprayed. It will be advisable to repeat this spray within ten or twelve days to effect complete eradication. Cultivation The production of a good tilth by the breaking down of the soil should be the aim during the present month. This will conserve the moisture so necessary for the healthy maintenance of the trees during the hottest periods of the year. Response to good cultivation is reflected in the robust condition

of the fruit trees, and the chances of fruit russet are reduced considerably, Weather conditions during the spring will determine to a large extent the frequency of cultivation, but advan-

tage should be taken of every opportunity to prevent the formation of a hard crust on the surface by use of harrows or cultivators. Pests and disease will be considerably' reduced

by clean cultivation right up to the trunks of the trees. * ' " — G. STRATFORD, District Supervisor, Dunedin.

Citrus Notes

Navel and Island Oranges

THE principal characteristics of the Spanish, Mediterranean, and blood oranges were mentioned in laist month’s notes, and there remain for •description the navel and Island orange varieties. The navel oranges probably comprise . the largest group of oranges planted in New Zealand. Varieties include Washington Navel, Thompson’s Improved, Golden Nugget, Groverley, Navelencia, Bahia, and Carter’s Navel. As trees; the navel orange varieties are rather dwarf, with rounded tops

and glossy green foliage. The fruit is characterised by a navel marking of greater or less extent. > Washington Navel is the best-known variety. Under equal conditions it is generally a smaller tree than most orange varieties. It is thornless, except for the young shoots, and has a marked inclination to “sport.” Leaves are alternate, dark green and larger than with most other varieties, the margin of the leaf being entirely or slightly wavy. The fruit ripens in September. It is large2J to 3J inches in diameter— globose in shape. Colour is deep orange at maturity. The flesh is rather coarse or “meaty,” but the pulp is melting and juicy. There is generally a small distinct navel and no seeds. Thompson’s Improved is not really an improvement on Washington except for its fine shiny rind. Internally, it is similar to Washington, but externally' it can be distinguished by the smoother rind, a higher orange colour,

sometimes a little elongated in shape, and generally smaller under equal conditions. The fruit of this variety must be picked early, as it is inclined to be lacking in juice. Golden Nugget arose as a Washington Navel sport. The tree has a pendulous habit, and is a dwarf grower. The fruit has deep furrows on the half of the rind next the stalk. This is more pronounced than with any other navel. Also, the fruit is large with pale, yellow smooth rind and internally free from rag. Groverley is a weaker tree than Washington, and the fruit is not as symmetrical. Like Golden Nugget, the fruit of this variety has furrows on the half of the rind next the stalk. It is large, yellow, and flatfish, but not quite seedless. Nayelencia is another Washington sport, and is generally of inferior quality on sweet orange and rough lemon rootstocks. The fruit is medium to large, smooth and thin skinned. Bahia is the old variety from which Washington originated. It is a vigorous variety, but somewhat; a shy bearer and fruit a little coarser than Washington. , Carter’s is a recently . introduced strain of Washington. . Island Oranges The Island oranges are of the type grown throughout ' Polynesia. The trees are generally thorny, vigorous

growers, but take a longer period in which to commence bearing. Local varieties are Best’s, Wright’s and Dacre’s oranges. . Best's is a local seedling formerly known as Best’s Seedless, but it is probably better to discard the latter part of the name, as it is not entirely seedless. The fruit generally bears a distinct navel, but the growth of the tree excludes it from the navel group of oranges. The fruits are irregular in

shape, but are generally flatter than navel oranges. The flavour is good, and the pulp exceptionally melting, and there are about 12 irregular sections. Wright’s is a sport from Best’s, raised by Mr. H. R. Wright, of Avondale, Auckland. The tree is quite thornless. The fruit is regularly flat and uniform in shape. It has a ribbed appearance on the half of the rind next the stalk,

as is noted with Golden Nugget and Groverley. The fruit is smoother in the rind than Best’s, but the same high quality is retained. y Dacre’s is another seedling, derived from Island oranges. 'The tree is a strong grower, and the fruit is roundish in shape and of average size and good flavour. In next month’s notes reference will be made to Mandarin varieties and Mandarin hybrids. ' —A. M. W. GREIG, Citriculturist, Auckland.

Citrus Bud Selection and Variety Tests In New Zealand

Do you know that New Zealand imports more than 500,000 cases of citrus fruits annually? Is this necessary? We have some good quality local grapefruit and lemons, and are searching for a variety of local sweet orange and mandarin which does well in the Dominion. Do you realise that every sweet orange growing country had to evolve its own particular varieties suitable for local conditions, and that the industry became successfully established only when such variety was discovered? Are you going to assist this work of finding the most suitable ' variety and improving our lemons, oranges and New Zealand grapefruit by careful bud selection ? IN the past the propagation of citrus trees has been done by seed, cuttings, layering, budding and grafting. To-day the standard method is by budding, a system of vegetative reproduction whereby the young citrus tree retains the characteristics of the tree from which the original bud ,was taken. . The selected bud is inserted into one . of the standard root-stocks for citrus trees, namely the sweet orange (.Citrus sinensis) , the Rough Lemon or Citronelle (Citrus limonia) , the trifoliate orange, (Poncirus trifoliata). Although rootstock and general environmental factors have a considerable influence on the development of the young citrus tree, trees planted out on the same rootstock and within' the same environment differ widely. In every commercial citrus , orchard to-day, there are many qualities of trees both in vigour of growth and in the quality and quantity of fruit produced per tree. This difference is largely due to the variation in the original buds from which trees were propagated. The citrus grower. in the past has paid too little attention' to the selection of his original trees, and when, by experience, he learns of his mistakes he may have spent many years of hard conscientious work on inferior trees. Not only should rootstock seedlings be severely culled, retaining only the strongest, but also the best available citrus buds should be budded on to those rootstocks.

The work of finding the .best buds available is known as bud-selection. This requires the observation and whole-hearted co-operation of every citrus grower as well as that of every citrus nurseryman. Generally, citrus trees have been propagated from the best available material known to the

propagator, but the individual person who was propagating the trees has been limited in his choice by limitedknowledge of trees available. Formerly buds were selected from one variety and at a later period selection was mainly confined to the strain within the variety, whereas to-day buds are, in the main, or should be, selected from the best trees or best portions of trees of a superior strain of a variety. Citrus bud-selection work has been carried out in other parts of the world, and the work of A. D. Shamel and his co-workers in the United States is well known. Similar work has been undertaken in New South Wales, and the necessity for such bud selection has been recognised in New Zealand for some years. In order to put citrus bud-selection on a sound basis and to co-ordinate past work, it is suggested that each individual grower become

an observer and report to the Orchard Instructor s and Citrus Growers’ Committee for the locality trees of outstanding merit for quality and quantity of crop in the orchard. Having selected the outstanding trees, it is proposed that fruits be assembled and exhibited locally from these trees and then forwarded to the Central Bud-Selection Committee for its selection and , comments. All selected trees would be marked and cropping record for the next three years obtained. At the end of this period there should be some reliable data in each district. It is recommended that no buds should be cut before the end of the three-year trial period. When definite proved trees have been secured after the trial period it is proposed to arrange for the securing of the buds and the supplying of nurserymen with them on conditions to be later agreed upon, and also to plant out bud-selected trees and encourage intending planters to inquire for trees, 1 using such tested and selected buds.

Using Bordeaux Mixture

FUNGOUS diseases of crops cause £ serious annual losses. Once the crop is seriously affected, control of disease is not easy. The plants may be coated with a protective film which, if complete, prevents the entry of disease organisms into the ' plants. For this purpose Bordeaux mixture applied as .a spray and allowed to dry on the plants is satisfactory with many plants, but every portion of the plant above the ground must be coated, and the covering must be renewed as the plant grows and as the Bordeaux loses in effectiveness. It may be necessary to spray at from 10- to 20-day intervals, or more frequently when warm humid conditions occur. Under the latter conditions the plant grows rapidly, the film of spray deteriorates readily, and infection by fungi is likely to be more serious. The spray should be applied when the plants are dry, and early in the day so that it dries. A dull but fine day without. wind should be selected for spraying. z Bordeaux mixture is prepared from copper sulphate (bluestone) and hydrated lime (slaked lime). Both ingredients may be obtained from good hardware stores and seed merchants. The copper sulphate (crystals or powder) costs about 8d per lb, and the hydrated lime about Is 6d for a 7 lb. tin. The lime should be stored in an air-tight container, and should

be used fresh. Any carry-over should not be used the following season. The strength at which to apply Bordeaux mixture in control of most diseases during the growing season is —that is, 3 lb. of copper sulphate (bluestone), 4 lb. of hydrated lime, and 50 gallons of water. Proportionate amounts of these ingredients are required when smaller amounts of the mixture are being prepared. Where 4 gallons of spray are to be made, 4 oz. of copper sulphate and 5 oz. of hydrated lime are required. The amounts of the ingredients should be carefully weighed. The following procedure should be followed ■ when preparing 4 gallons of 3:4:50 Bordeaux:— (1) Dissolve the copper sulphate in 2 gallons of water in a wooden, earthenware, copper, or glass vessel. Hot water may be used. (2) Add i water to the lime, and stir until it assumes the consistency of paste. Then dilute it with 2 gallons of water. (3) Mix the two solutions, stirring vigorously while doing so. The spray is then ready for use. It should be used immediately," as it loses in effectiveness if kept for any time. When the crop requires a further spraying a fresh mixture should bemade. - , .

Reminders for the Month. Continue systematic pruning, giving particular attention to trees affected by frost or. citrus brown-rot. ' Remove dead wood from citrus trees. This is the natural breeding ground of the citrus-borer. Check the citrus trees for bark-blotch. Early detection and treatment is essential. Apply a 3-4-50 Bordeaux mixture spray during October. This is of the greatest importance to young lemon fruits. Harvest your citrus fruits with care.

Cool Storage Notes On page 347