In the Orchard and Vineyard

New Zealand Journal of Agriculture, Volume 66, Issue 4, 15 April 1943, Page 234

In the Orchard and Vineyard

Orchard Notes

Current Work in the Orchard

WITH the bulk of the harvesting completed growers will now be concentrating on the late varieties. As large quantities will be required for cool storage, harvesting of each variety should be speeded up as soon as its correct stage of maturity has been reached. Delay in harvesting Sturmer apples may. lead to the incidence of “ripe spot.” This disease, which develops and spreads rapidly, has in past seasons caused considerable loss in this variety. Fruit affected with “ripe spot” should not be held in either orchard storage or cool storage as infection is likely to increase, To. avoid the multiplicity of 'minor bruises and grader markings so often found when cases of Sturmers are opened, for inspection, careful handling of the fruit is essential. Sufficient toughening of the skin of the fruit to prevent much minor marking may. be induced by holding Sturmers two to lour . days after picking, and before passing them over the grading machine. ... Periodical inspections should .be made of all orchard stored fruit which should be packed and forwarded to the assembly depot before maturity becomes too advanced for marketing.

Autumn Ploughing

Deep ploughing of the orchard in the autumn is recommended for all but very wet soils, or soils which are likely to scour badly during the winter rains. It is advisable to plough up to the trees, leaving the open furrow in the centre of the rows to facilitate drainage. For very wet soils, or those likely to erode readily, the land should be in green crop all . winter. The .green Crop will act as. a de-water-ing agent and the soil will therefore be in a better physical condition in the spring; erosion will also be prevented.

Manuring

Of the plant nutrients only nitrogen, phosphorus, potassium, and calcium are in general short supply in New Zealand soils. Replenishment of these elements must be made annually if soil fertility is to be maintained at a profitable level. ' Replenishment is usually made in the form of manures. Manures are classified as nitrogenous, phosphatic, potassic, or

General Maintenance

combination . manures, according to ■their constituents. Nitrogenous manures include .nitrate of soda, sulphate of ammonia, and dried blood.. Phosphatic manures . include . superphosphate, basic slag, rock phosphates, and bonedust. Potassic manures include sulphate of potash, muriate of potash, and potash salts.. Combination manures are those which contain more than one of the foregoing elements and include ammoniated superphosphate, blood, and bone, meat meal, and fish manure. Manures are at times classified as artificial manures and organic manures. Artificial manures include nitrate of soda, sulphate of ammonia, superphosphate, rock phosphates, basic slag, sulphate of potash, muriate of potash, and potash salts. Organic manures include dried blood, meat meal, fish meal, guanos,- blood and bone, bonedust, . wood ashes, animal manure, and plant refuse. . • • . The artificial group are quicker-act-ing and may be applied where a quick response is required. Organic manures are somewhat slower in action but are generally available over a longer period. The majority of the manures we have been accustomed to use are now in • short supply ' and ' are rationed. The quantities which are available are insufficient to meet the needs of growers, and steps should be taken to supplement the manure supply by the growing and turning under of cover crops. Plant refuse provides a complete manure, containing . nitrogen, phosphorus, and potassium, and this method of enriching the soil should not be overlooked, particularly at the present time. ' With the application’of manures, the slower acting phosphates and potash should be spread and ploughed under in the autumn. Nitrogenous manures, especially such soluble ones as nitrate of soda and sulphate of ammonia, should not be applied until the spring.

As the harvesting season draws to a close there is usually a partially slack time prior to the commencement of pruning .operations. Advantage should be taken of this to. carry out the necessary work of clearing drains, trimming

hedges and shelter belts, and collecting up the orchard cases, repairing damaged ones, and stacking away, for the next season’s use. Waterlogged soils during the winter are cold soils in the spring, and cold wet soils may seriously retard spring growth and root development, and upset the normal functions of the trees at fruit setting time, resulting in loss of crop. Drains should be cleaned before the heavy winter rains;make this work difficult, and where it is found that insufficient drainage has been provided, new drains should be made. When the packing operations are concluded, thoroughly clean,the grading table and all parts which have come in contact with the fruit. Accumulations of grit and dirt are far easier removed immediately ' after operations have finished than if left to become hard and dry. Clean up the shed thoroughly, and remove and destroy all reject fruit. Hammer, nails, case liners, and wrapping paper should be gathered up and stored away for the next season. Preparations should be made for the wet-days job during the winter months of overhauling and cleaning the spray outfit, attending to minor repairs, and cleaning of . the farm: motor truck, cleaning and greasing of : farm implements. Many growers take the opportunity during wet days in the winter to give their implements a coat of . paint in order to preserve them, and lengthen their working lifeall growers would be well advised to follow this sound practice where possible. i —R. G. I. HAMILTON, District Supervisor, Horticulture Division, Auckland. ... >

Two Common Pests

Two of the most common pests of cabbages, rape, turnips,, chou moellier, etc., are the white butterfly and the diamond-backed moth. No doubt a good deal of confusion exists among the farming, community in regard to the damage caused by the white butterfly and the diamond-backed moth, and injury caused by the latter insect is all too commonly . blamed on the white butterfly. The fact that butterflies are seen over a crop is not sufficient evidence for. attributing any injury to their presence, and the only way to determine the cause of the injury is to examine the crop. The differences between the two insects and the type of injury they cause are described in a special bulletin issued free by the Department of Agriculture.

Citrus Notes

Citrus Pests

IN this month’s notes it is proposed to discuss citrus scale insects recorded in New Zealand, their recognition and control. Before doing so, a brief outline of their place in the classification of insects will be given. Insects are characterised by the following points: — 1. Small size— more than 3 inches across. 2. Body divided into three segments—head, thorax and abdomen. 3. Body covered by an external nonliving cuticle or shell. 4. Three pairs of legs, jointed and attached to the thorax. 5. Wings, if present, also attached to : the thorax. The insect pests . recorded in New Zealand can be subdivided into: — - 1. Chewing insects. ' " 2. Piercing and sucking insects. 3. Rasping and sucking insects. 1. Chewing Insects, by moving their mandibles from side to side actually •chew the plant tissues. Citrus chewing insects are Dicky-rice-weevil, Maleuterpes spinipes, Leaf-rbller-caterpillar, Tortricid moth spp., and Citrus-borer, Aemona hirta. 2. Piercing and Sucking Insects have the mandibles and ' maxillae joined to form a proboscis which the insect inserts into the plant tissues and through 1 which it absorbs the sap of the tree. Citrus piercing and sucking insects are: Black aphis (.Aphis citricidus); Mealy bug (long-tailed) (Pseudococcus adonidum); Mealy bug (short-tailed) (Pseudococcus maritimus); Circular-black-scale (Chrysomphalus rossi); Hemispherical scale (Saissetia coffeae) ; Olive-scale (Saissetia oleae) ; Red-scale (Aonidiella aurantii) ; Hard-wax scale (Ceroplastes sinensis'); Soft-wax scale (Ceroplastes destructor) ; Cottony cushion scale . (Icerya purchasi) . 3. Rasping and Sucking Insects have three sharp horny needle-like. organs which rasp the plant tissues and then suck the sap from the wounds. In this category are Thrips, Heliothrips haemorrhoidalis and the Red-mite (a spider) Paratetranychus citri. Scale insects are characterised by the fact that the adults have a sedentary habit and either' live beneath a scale or have the upper surface thickened with a homy or waxy material. Male scale insects have 1 pair of wings or are wingless; the females are always wingless. Most scale insects lay eggs but the Red-scale, Aonidiella aurantii, is viviparous. Scale insects are spread from tree to tree at the “crawler”

stage by wind, birds, or by men through transporting infested fruits, prunings, young trees or implements. Rain also washes larvae from the higher to. the lower parts of a tree. Of all the scale insects, the two most serious in their effects on citrus trees are the Hard-wax-scale and the Redscale. The Hard-wax-scale, Ceroplastes sinensis, is becoming very common and is a serious menace not only to citrus trees,, but also to ornamental and native trees and shrubs. The wax-scale is readily visible and 4 is characterised by: ‘ ...' , ' .. '' 'i 1. Its waxy appearance. 2. The thick red blood-like juice it exudes when squeezed. ■ 3. Honey dew being copiously secreted and on this the sooty-mould

fungus, Capnodium citricolum grows. 4. The star-shaped appearance of the young which may be seen along the main and side veins on the upper surface of the leaves generally in May. 5. The adults being usually found aggregated on the stems. The Red-scale Aonidiella aurantii is relatively small and yellowish to red-dish-brown in colour. Unlike the Hard-wax-scale, no honey dew is secreted so the presence of Red-scale cannot be detected by any Sooty-mould. The Red-scale infests the foliage, twigs, trunk and fruits of citrus, being more prevalent on lemon fruits than on the fruits of orange and New Zealand grapefruit. Red-scale thrives on sickly trees and its early detection is very important. The main trunk of a tree may be covered ’with Red-scale , before the branches, twigs or fruits show infection. It may thus occur that an orchard which may appear to be free from Red-scale, is really severely infested and, when conditions are favour-

able for its development, chiefly in the summer months, the scale will appear with alarming suddenness. Of the remaining scales the most common is probably the Olive-scale, Saissetia oleae, which secretes honey dew like the Hard-wax-scale, and thus indicates its presence by Sooty-mould. When young the Olive-scale is brown in colour; when mature a very dark brown witih a characteristic marking like a raised “H.” Other hosts of the Olive-scale include the rose, guava, pear, palm, apple, plum, grape, wis-

teria, pepper, holly, laurel and camellia. The Hemispherical-scale Saissetia coffeae seldom is associated with Sooty-mould but is similar to the Olive-scale in that an H marking can be seen on the young. This marking, however, disappears at maturity and the adult scale is brown, smooth, shining and highly convex. Hemispheri-cal-scale usually infests young twigs of citrus and also occurs on the oleander, palm and camellia. The Circular-black-scale, Chrysomphalus rossi, is almost jet black and

flat, except for a light brownish grey “boss” in the centre. Sooty-mould is not generally associated with this scale which infests orange fruit, the upper and lower surface of other citrus leaves as well as Eleagnus, Euonymus, Eucalyptus, oleander and camellia. The hard-wax-scale, Ceroplastes sinensis, is most readily controlled in April and May by the application of a one per cent, certified summer oil. A. M. W. GREIG, Citriculturist, W ellington.

Cool Storage Notes

Care of Refrigerating Plants

WHEN the cool storage chambers are being rapidly filled with fruit during the harvesting period, many of the refrigerating plants are heavily taxed daily to cope with as much as a 35° reduction of temperature of the incoming fruit. In dealing witih this heavy duty, particularly when the dry battery system of cooling is in use, the cooling pipes become heavily coated with snow or ice which has been formed by the condensation of moisture from the storage atmosphere upon the cold surface of the ammonia piping. This frost accumulation on the pipe surfaces, if not removed by defrosting at regular intervals, has the effect of reducing by from 15% to 25% the rate of heat transfer from the circulating air to the pipe surfaces, as when the cooling pipes are coated with a ring of snow or ice the previous rapid evaporation of the refrigerant within the pipes gives place to a slow or retarded one. Regular attention to defrosting these pipes will maintain them at their full cooling efficiency, and save labour and power costs for running the refrigerating plant. Where the direct expansion ceiling system of cooling is in use, in which the cooling pipes are open spaced and distributed evenly overhead in the chambers with trays suspended from the pipes to drain away the condensed moisture from the storage atmosphere which drips from the pipe surfaces, the frost does not accumulate on the

pipes or in the drip trays unless temperatures lower than 33° F. are maintained. This is due to the position, and open-spaced formation of the cooling pipe circuits which are placed at a point near the ceiling of the chamber, where the lighter warmer layer of air is constantly coming in contact with the cooling pipe surfaces. When the refrigerating plant is not in operation each day, the frost quickly disappears from the pipes and is drained away. In maintaining lower temperatures of 29° to 32° F. for pear storage, special

defrosting connections and equipment are necessary for defrosting the pipes and drip trays at regular intervals, particularly during the harvesting period when warm fruit is being received for storage. By the use of the direct system of cooling, storage temperatures and the relative humidity of the atmosphere may be controlled with the minimum amount of fluctuation. Attention should be given to the purging of air and foreign gases from the ammonia condensor at regular intervals, and the oil separator should be constantly drained of oil and weak ammonia liquid. The refrigerating plant should be kept fully charged with ammonia.

A. A. POWELL,

L, Cool Storage

Officer, Wellington.