The Home Orchard in Summer

New Zealand Journal of Agriculture, Volume 99, Issue 5, 16 November 1959, Page 477

The Home Orchard in Summer

By

D. W. McCALLUM,

Horticultural Instructor, Department of Agriculture, Blenheim

Rarely will a single application of any spray control a pest or disease of fruit trees. No single spray application or even a complete spray programme can be effective unless it is applied when the pest or disease is in a condition to be affected by the material used. A knowledge of the life cycle of the pest or disease is therefore necessary if sprays are to be correctly timed. A major pest of pip fruits is the codling moth (Cydia pomonella), the life cycle of which is described in this article giving suitable control measures. Routine summer work is also discussed.

CONTROL OF CODLING MOTH

’T'HE codling moth, regarded as a native of south-east Europe, has spread wherever apples and pears are grown throughout the world. The larvae bore into apples and pears, eating, their way through to the core and making the fruit commercially valueless. When control measures are not adequate it is undoubtedly the most injurious pest of these two important fruits. Stone fruit and walnuts may also be attacked, but rarely severely enough to justify control measures.

The adult moth has a wing span of nearly f in. and is bluish . grey and most inconspicuous against the grey bark of trees where it rests during the day. The forewings are a pale grey, but the uniformity is broken by irregular, dark, wavy transverse lines and a coppery spot near the tip. The hind wings are greyish brown throughout but slightly darker near the margins. The moth is active only at night. The eggs are about the size of a small pinhead, pearly white when laid but darkening as the embryo develops. The newly hatched caterpillar is white with a relatively dark head. When fully grown it may be up to an inch long and is yellow or pink in the body with a pale brown head. The insect overwinters as a fully grown caterpillar protected by a white webbing. It can frequently be found in cracks in the bark of fruit trees, but

it will hibernate anywhere it is likely to find shelter. In spring these caterpillars pupate and remain in this state for from three to eight weeks, depending on the locality and climate. After mating, the female moth lays eggs on young fruits, leaves, and twigs. After about ten days the young caterpillars hatch out and find their way to the fruit to begin feeding. After three or four weeks the caterpillars are fully grown and they emerge from the fruit to seek a suitable place to pupate. Affected fruit frequently falls to the ground before it is ripe, but even if it remains on the tree until it is mature the fruit is unattractive and subject to rots. Fruit may be attacked over a long period which varies according to the climate. Investigations over the past few years in Nelson have shown

differences of several days between peak moth flights in areas only a few miles apart. In the South Island and in the southern half of the North Island there is usually only one generation in a season. From Hawke’s Bay north there is frequently a small second generation. Spraying to control codling moth should begin about mid November and carry on until late January. Two materials are in common use, arsenate of lead (1| oz to 4 gallons of water) and DDT. The dilution of DDT varies according to the strength of the formulation used and manufacturers’ recommendations should be followed. Both materials have their advantages and disadvantages. Arsenate of lead is effective against leaf-roller caterpillar and DDT is not. Further, DDT is toxic to several beneficial insects which prey on woolly aphis and red mite, and a build up of these, pests is likely if DDT is used continuously.

Arsenate of lead has a harsher effect on the foliage of fruit trees, especially when combined with lime sulphur, and russeting of the fruit may occur. However, this is probably not very important in the home garden. Arsenate of lead should not be used on stone fruit trees, as it is likely to cause damage.

SEASONAL WORK Thinning of Fruit One of the most neglected tasks in the home orchard is the thinning of fruit, yet few practices do more to ensure regular crops of good quality. Apples Naturally large varieties of apples such as Ballarat need little or no thinning in most seasons. Long-stemmed varieties such as Golden Delicious and .Rome Beauty which normally bear consistent crops may quite well be left unthinned. Most other varieties require thinning. Recommendations for more common varieties are: Sturmer— -Reduce fruit clusters, to three fruits Jonathan — Reduce fruit clusters to one or two fruits Gravenstein — fruit clusters to two fruits Cox’s Orange ßeduce fruit clusters to three fruits. Delicious ßeduce fruit clusters to three or four fruits Thinning of apples is best delayed until mid December, when the natural drop will have taken place and the orchardist has a better idea of his potential crop. Pears Pears require thinning only when there is an exceptionally heavy crop, but an exception is Winter Cole, which is reluctant to swell . its fruit unless thinned. Stone Fruit Thinning is important with all stone fruit. . Clusters, should be broken up and fruits remaining should not touch even when fully grown. Passionfruit Where passionfruit grows and produces well considerable quantities of plant foods are taken from the soil. If vigour is to be maintained, these must be replaced. A mixture of 2 lb of blood and bone, J lb of sulphate of ammonia, | lb of sulphate of potash, and | lb of superphosphate should be applied to each vine in December and again the following August. Younger vines which have not yet begun cropping need only about 1 lb of blood and bone before cropping begins. ‘ A regular supply of moisture also is necessary for good growth and vines should be irrigated before the land dries out too severely. Extreme dryness causes premature defoliation and the dropping of fruit.

Currants As with most other small fruit currants must be fully ripened before harvest if the best flavour is to . be developed. Currants are frequently irregular in maturing, but modern varieties hold their fruit well and normally it is best, to delay harvesting until most or all of the fruit on a truss is ripe. Pest and Disease Control Powdery Mildew Powdery mildew, a fungous disease, can be severe on apples, particularly on the more susceptible varieties such as Jonathan, Cox’s Orange Pippin, Sturmer, and Rome Beauty. It attacks leaves, shoots, and fruits, but symptoms are most apparent on the leaves. The terminal leaves on young shoots are usually the first affected. They remain small, are more or less covered with a grey or white film of the fungus, and will probably fall early, leaving an unthrifty shoot with distorted buds. . Colloidal sulphur di oz of 40 per cent material) plus lime sulphur (4 fl. oz.) to 4 gallons of water will check the spread of this disease. These two. materials may be combined with the insecticide used for codling moth control.

Raspberry Rust Until a few years ago raspberry rust was confined to the North Island, but it now appears regularly in Marlborough and Nelson, though not severely enough to cause much damage. Spray after the berries are harvested with lime sulphur (4 fi. oz.) and colloidal sulphur (1J fl. oz.) in 4 gallons of water. ■ The infection overwinters on fallen leaves and a further spray in autumn .at leaf fall will reduce infection, further. Red Mite Red mite frequently becomes severe during summer. Apples are mainly affected,’ but other tree fruits and berry fruits may be attacked, especially in areas of low humidity. Affected leaves are lighter in colour and in severe attacks will become brown and brittle. Fruit on affected trees will remain pale and dull. The spray recommended for powdery mildew control will help to keep mites at bay on apples, for they are intolerant of lime sulphur. Otherwise two summer oil (2 fl. oz. to 1 gallon of water) sprays about ten days apart will give satisfactory control. This material should not be used within a fortnight of using lime sulphur; otherwise plant damage will occur. Thorough coverage is essential to give control of the mite.

Aphids on Currants Currants are sometimes affected by aphids. The foliage, especially near the tips of branches, curls up and if the attack persists becomes pale. Growth is checked and the following season’s crop will suffer accordingly. Summer oil (2 fl. oz.) plus nicotine sulphate (1 teaspoon) to 1 gallon of water will control the aphids. The spray will require to be repeated about ten days later. Malathion or lindane sprays would also be effective. Grass Grub * • Grass grub may be controlled by applying 1| lb of 50 per cent DDT to 1,000 sq. yd. Need for Wafer All types of fruit are sensitive to a lack of moisture, especially in the weeks preceding maturity, when the fruit is swelling rapidly, and water should always be given before the ground becomes too dry and the plants begin to wilt. If the vegetable garden needs watering, the home orchard will need it too. All photographs by Shell.

Sod Seeding Cereals into Pasture for Winter Green Feed

LAST autumn several trials were laid down in Canterbury to investigate the suitability “■ of sod-seeded cereals for providing increased winter green feed on dairy farms engaged in whole milk production. The interim results of these investigations up to the first grazing, which was carried out 10 weeks after seeding, have been sufficiently promising to justify a review of the relative merits of this new practice. .. .

ONE trial was carried out on a pasture which was dominantly ■cocksfoot but which also contained perennial ryegrass and white and. red clover. It had been severely affected by the drought. The heavy clay soil was hard . and dry. Rain soon after seeding resulted in a good strike of the cereals and a good recovery of the pasture. “* Another trial was sown in . a two-year-old clover-dominant pasture. As the result of spray irrigating the pasture before seeding the drilling in of the seed was assisted and a good strike was gained. Some varieties were -through the ground within 10 days. The cereal varieties included were C.R.D. ryecorn, Wong barley, Cape barley, Arawa wheat, Russet oats, Algerian oats, and Winter Grey oats with Italian ryegrass for comparison.

All are being studied for productiveness, recovery ability, freedom from disease, and palatability. ’ All treatments were drilled with a sod seeder, fertiliser and seed being sown together through ••• the manure run. The cereals were sown at the two rates of 2 bushels and 1 bushel per acre and the Italian ryegrass at 1 bushel and J bushel per acre. Two. rates of fertiliser were also applied. The high rate was 3 cwt per acre of an • ammonium-nitrate lime mixture and 1 cwt of superphosphate; the low rate was half of this. Further investigative work dealing especially with fertiliser usage remains to be done, but from results so far a minimum quantity of 1 cwt of each of a phosphatic and nitrogenous fertiliser per acre is required to ensure rapid establishment of the crop.

Experience with varying seeding rates suggests that a seeding of from 2-J to 3 bushels per acre will give satisfactory results. Observations indicate that high seeding rates tend to suppress the contribution, by the grasses and clovers. The suppression covers may be desirable in some instances of the cereals tested to date all except Algerian oats have thrown a good bulk of feed within 10 weeks of sowing, the erect types like Abundance, Russet, and Winter Grey oats and Arawa wheat doing particularly 2“ this respect. C.R.D. ryecorn p ?ostSe In careful grazing management The first two can be relied on to give excellent recovery growth throughout the late winter . early spring period provided grazings are carried out w hen growth approximates 4 in. in height.

—D. J. G. DAVIES,

Fields Instructor, Department of Agriculture, Christchurch