HORTICULTURE.

New Zealand Journal of Agriculture, Volume 54, Issue 6, 21 June 1937, Page 378

HORTICULTURE.

Some Soil Pests.

Where humus is abundant and tender seedlings are plentiful, a hungryhost of insects will often be found feeding upon them unless steps are taken to study the creatures and check their ■ depredations , before they become excessive. In shaded . moist positions they will be chiefly slugs and snails : in warm sheltered places the . crustaceans known as slaters or wood lice are most plentiful. ■ In the more open spaces a dark stout caterpillar, commonly known as a cutworm, the larva of one of the larger heavy-flying

summer moths, lies dormant in the soil during the day, but does an enormous amount of harm at night feeding on the roots of young plants, or- even cutting them down completely just at the surface of the ground.- While small and-tender the - seedlings are easily injured, and the cause of their slow growth or total- disappearance is often unsuspected, so closely hidden are their enemies during the day. Inspection with, a torch at night reveals these usually sluggish creatures in a state of great activity, which is a contrast to their behaviour during the hours of daylight. Some protection is often required to enable the crop to grow away quickly or even prevent its total destruction. . . Bluestone in any form is most effective in destroying slugs ; 18 lb. finely ground and mixed with 3 cwt. kainit or other fertilizer per acre will afford protection. Powdered alum is also a powerful deterrent; or a solution, J lb. to' a gallon of water, may be sprayed after sundown when the pest is active. The' powdered alum mixed with twice, its weight of lime and applied at a rate of J cwt. per acre is most economical. ' .' ' For this and other pests mentioned above the most generally useful dressing is a bait composed of 1 lb. paris green and 28 lb. bran thoroughly mixed in a dry state. It is then made into a flakey mash with water and broadcasted towards evening, : when the insects become active. Arsenate of lead powder, 2 lb., may be used in the place of paris green'. This quantity is sufficient for an acre. It is best applied when the land is fallow; a few days before sowing or planting. . Good reports have been received of a new slugicide made of one pint of •bran mixed with one “ meta.” tablet finely ground. These tablets, used for heating, are composed of metaldehyde and obtainable from chemists. They are not soluble in water. The remedy is useful in home gardens where a poison bait may be objectionable. Vegetable Crops. It is usually towards the end-of the month of July before much can be done with annual vegetable crops. On sheltered light land, and elsewhere where it is warm, a commencement may be made by planting out shallots, garlic, cabbage, and cauliflower ; also sowing early peas, spinachj and salads. Of the perennial crops, rhubarb may then be planted, but asparagus is best left until the following month. .. . . Of all. the factors contributing to a good crop, the application of artificial fertilizers is one which receives considerable attention. This powerful aid to good cropping requires very nice adjustment .to obtain the best results. It . is. not merely, a question of obtaining . a chemical analysis of the soil and making good the deficiencies .by use. of chemical fertilizers ; the heavier dressings of fertilizers are often applied to the richest land. The results of high feeding may be heavy crops, exceptional quality, or serious ' loss from disease, the latter usually occurring when the application is badly- balanced as to its ingredients, the application is -badly timed, or -may be unsuited' to the soil or the crops. Extremely heavy applications of fertilizers are to some extent a gamble, and they should be made only by those .with a long experience of a locality. The result depends very largely on the weather experienced after the application is made. Under most circumstances it is best to apply a moderate dressing before sowing and planting, and side-dressings afterwards as may be required ; then if the drainage, is good ; and the lime requirement of the soil is. watched the best results from the fertilizers may be expected. . ... ...

The kind and quantity of fertilizers to be used with each crop must be carefully adjusted after considering all the circumstances. For crops of the

cabbage family 3 cwt. to 6 cwt. of superphosphate and i| cwt. to 3 cwt. of sulphate of potash worked into the land before planting will often be satisfactory where a good dressing of farm manure has been turned under in the preliminary preparation. Where farm or stable manure has not been used, half a ton or so of blood and bone or fish manure should be incorporated during the preparation of the land. If 1 cwt. or 2 cwt. of nitrate of soda are applied as a side dressing when the plants are established and this is repeated when they commence to heart up it will often be found satisfactory. Somewhat similar treatment is suitable for salad crops. Where the land is heavy 1 cwt. or 2 cwt. of sulphate of ammonia may be included in the dressing before planting and the first dressing of nitrate of soda omitted. Culinary peas, like most other crops which are required to flower and seed, do not require so much nitrogen as the preceding. Where the land is in good heart from previous dressings the superphosphate and potash quantities mentioned above will probably meet their requirements. In preparing land for rhubarb a heavy dressing of farm manure is turned under and 3 cwt. to 6 cwt. superphosphate per acre is worked in before, planting. Small and Sundry Fruits. In the warmer districts the tomato crop under glass is planted out towards the end of Julyin middle districts about the end of August. During recent years it, has been necessary to stress the damage caused by the excessive use of stable manure before planting out this , crop. The danger is greatest where the water-table in the subsoil is comparatively high, or where the land is heavy . and drainage is inclined to be defective. It is, however, necessary, to maintain fertility, to keep up a supply of humus in" the soil by means of stable manure or cover-crops. The need will specially require to be watched where the subsoil is open and where steam sterilization of the soil is practised. In preparation for planting a dressing of artificial fertilizers should be worked in two or three weeks previously. In the absence of local data the following moderate dressing may be used to the square yard : J lb. bonedust, 2 oz. superphosphate, and 2 oz. sulphate of potash. In preparing the tomato-plants for setting out it will generally be advisable to fumigate them with nicotine to destroy aphides. Insect infestation is generally the main cause of virus disease in this crop under glass, and treatment is more easily given before than after planting out. Planting-distances are important; they should be widest in warm humid localities especially where ventilating facilities are limited, as is so often the case. Under such circumstances 12 in. between plants and 30 in. between rows will not be excessive, but in any case the rows should not be closer than 24 in. to obtain the best results. About the month of July, as autumn-planted strawberries commence to make growth, a small dressing of blood and bone manure worked into the ground between the rows will usually be beneficial ; a little superphosphate may be included if desirable ; established beds may be given a' similar dressing. Two or three such dressings at intervals will build up the plants for heavy cropping. In at least one dressing 1 cwt. per acre of sulphate of potash should- be included in the mixture. The quality and demand for persimmons, Cape gooseberries, and tree tomatoes on the market at the present time suggest that more attention might be given to the production of these and other kinds of fruit that are not usually grown. It is evident we have not fully realized the possibilities of the resources we have in the land and climate of New Zealand, especially in the warmer sheltered localities. Avocados, feijoa, and figs are also produced in excellent varieties and quality,. and planting might well be

extended where they are doing well. Up to the present avocados have borne fair crops in the Gisborne district only, and some pioneer work still remains to be done, more particularly in the matter of variety trials. It is a very wholesome fruit and when the public have acquired the taste it should be in good demand. This is the planting-season, and consideration might be given a practical turn by making arrangements for planting during the months of August and September, if only a few trees, of this class as an experiment. The Homestead Garden. Where new gardens are being made the formation should be pushed ahead as weather permits, so that it may have time to consolidate before sowing down the lawns during the months of August and September. It is important that the surface should be at the right height, that it should be smooth, that the grade should fall away from the dwelling, and all surface water properly accommodated. These points should be verified positively before sowing the seed. . Ah alternative method is to make new lawns by laying turfs. For small gardens where the area of the lawn is limited this method is very suitable ; also in making minor alterations in an established garden, as when turfing-down old borders or making new beds. Worn patches in a lawn, about the centre or verge, are best repaired by turfing — in mild weather when the land is sufficiently dry. Consideration should now be given to the pruning requirements of plantations, shrubberies, and climbing plants. In many parts of the country trees mutilated by careless pruning are an unpleasant spectacle, and their value as timber or for shelter purposes is seriously discounted. ’ With systematic attention there should rarely be a necessity to remove large limbs : where it does occur the cut should be clean and flush with the trunk, or just beyond a good lateral growth. To do this a sharp saw is required and an under-cut should be made first, so that when the limb is severed from above it will fall without ripping the bark. If Stockholm tar or a thick paint is then applied to keep out moisture and decay, the tree will be preserved, and also its appearance and usefulness so far as possible. The necessity of such major operations arises through encroachment or congestion, and when examining trees and shrubs now such developments should be prevented by the timely removal of the branches causing it while they are comparatively small. Congestion or crowding of the branches, especially about the centre or the base of hardwood plants, is unsatisfactory and should be given attention from the commencement when the plants are first set out. Where, in addition to this, pruning is done to encourage the production of flowers, and possibly fruit, the habit of the plant must be more closely studied to ascertain, for instance, whether the flowers are produced on new wood, as in the case of roses, bougainvillea, and so many others ; or on young wood that is of last season’s growth, as in peach and weigela ; or on spurs on the old wood, as in apple and wistaria. The shrubs and climhdis grown for blossom should be closely studied from this point of view while at the same time realizing that such subjects usually require rather generous feeding to enable them to maintain the display. In most plantations and shrubberies the annual mulching of leaves which fall from the trees in autumn or spring is sufficient to feed the roots, but in the case of the more ornamental sections, where much blossom is expected, a dressing of bonemeal and well - decayed farm manure will be of great assistance. This should be worked in by means of shallow cultivation, as any serious disturbance of the roots is injurious. ?

—W. C. Hyde,

Horticulturist, Wellington.