HORTICULTURE.

New Zealand Journal of Agriculture, Volume 43, Issue 4, 20 October 1931, Page 300

HORTICULTURE.

Curing Organic Manures.

It is at this time that the materials for these valuable manures should be accumulated and properly cured, so that they may be ready for topdressing berry crops in the autumn and turning under in the winter when land is being prepared for vegetable crops. Animal and vegetable refuse are intended by nature to nourish plant growth, and the neglect to gather and properly store them is very bad management. Chemical inorganic manures are useful as supplementary plant-foods, but they can never take the place of the organic manures which are the source of fertility in soils. As it is rarely convenient to dig them in in a raw state, they should be stacked and fermented in much the same way as ensilage is made. Those who live by the seashore should also remember that seaweed comes under this heading. For further information on this subject see page 362 of the Journal for May last. Small-fruit Culture. For two or three months, commencing at the present time when the last of the stored apples are being marketed, and terminating in January when the stone-fruit harvest commences in earnest, is a period when the small berry fruits of summer-time are looked for. First come the gooseberries and strawberries, followed by the raspberries and currants in December. The gooseberries are harvested green and firm in a suitable form for culinary use. When of a comparatively even size they look well and are packed to best advantage. All mature berries in the strawberry beds should be gathered every two or three days. If any are overlooked they are either wasted, or, what is worse, gathered when overripe and spoil the pack. Mixed maturity is one of the worst defects in packed fruit. The fruit should be gathered when the surface is dry, and always kept in a cool shaded place while awaiting shipment. Weak and surplus canes should be removed when hoeing weeds in the crops of raspberries and loganberries. Cape gooseberries should now be planted out; 3 ft. apart and 6 ft. between the rows is suitable spacing on land that is rather rich. Plants of the >edible passion-fruit may also be planted, if this is not already done ; 8 ft. to 10 ft. between the plants and 10 ft. or 12 ft. between the rows are the usual distances. This distance between the rows appears excessive, and it is possible that 8 ft. or 9 ft. would be sufficient and more profitable. Cultivation to keep down weeds and carefully training the plants on the trellis provided are the main operations at this season. The Tomato Crops. Tomato plants in unheated glasshouses will now commence to ripen the lower bunches of fruit. This fact, together with the higher temperatures usually experienced, make it desirable to apply a mulch of strawy stable

manure, which will feed the loaded plants and conserve moisture in . the ground. This will save labour and maintain better conditions for the crop. If this is done and a close atmosphere with a high temperature is carefully avoided, there should be no difficulty in ripening the crop satisfactorily.

If the white-fly (Trialeuwdes vapor ar iorum) makes an appearance the house should be fumigated overnight with calcium cyanide, a material that slowly gives off a gas .which destroys all insect life. Hydrocyanic - acid gas has been used for this purpose for many years. It was done by tipping sodium cyanide into a solution of sulphuric acid. This resulted in a sudden rush of gas which was all released in a few moments, thus making it quite dangerous for the operator if, by carelessness or accident, he should be delayed in the work. The grade of calcium cyanide suitable for this work is known as “G ” fumigant. The particles are'about the size of sea-sand. The necessary amount can be weighed out, placed in a canister with a perforated lid, and evenly scattered down the paths through the glasshouse by shaking the cannister. This method is cheap, effective, and practically fool-proof. It' is safe because the gas is evolved slowly, so that there need be no anxiety on the part of the operator if the work is carried out methodically, and, although only a small amount of the material is required, it is effective because the gas is liberated over a comparatively longer period. The average dose is J oz. to 1,000 cub. ft. of space in the house ; but if there is much leakage and this dose has not the desired effect the treatment should be repeated after an interval of one week, increasing the dose to | oz. for every 1,000 ft. It is sufficiently accurate to regard a level tablespoonful of this material as equal to -J oz. The cubic feet of space may be ascertained by multiplying the average height by the length and breadth. For instance, in the case of an even-span house add the height to the ridge, say, 10 ft., to the height at the eaves, say, 5 ft., and divide the sum, 15 ft., by two, thus obtaining the average height of 7 J ft. Multiply the average height by the width of the house, say, 25 ft., and the area of the end is obtained, 187 J sq. ft. Multiply the area of the end by the length of the house, say, 100 ft., to obtain the capacity of the house, 18, cub. ft. As J oz. of calcium cyanide is needed for each 1,000 cub. ft., the house specified would require eighteen and a fraction quarter ouncessay, nineteen, as few glasshouses are very airtight. This equals qf oz. of calcium cyanide “ G ” fumigant which would be required for one treatment.

There are a few other conditions which should be observed. The treatment is best given shortly after sundown on a still evening, so that the leakage of gas will be at a minimum. Spread the cyanide evenly down the centre walk, leave the house at once, and lock the door. If the doorstep is worn, place a wet sack in position to prevent leakage beneath the door.

Other conditions necessary are a moist atmosphere of 55 to 80 per cent, humidity, and dry plants’ This would be about the average humidity in a crop of tomatoes under glass during summer, and the plants will remain dry if the temperature of 55 0 to 75 0 F. is evenly maintained, since falling temperatures produce moisture. The reason for this is that the calcium cyanide is acted on by the atmospheric moisture, and the gas is thus slowly evolved, but if the plants are wet the water would absorb the gas and the plants would be liable to injury. The explanation may make the operation sound elaborate, but the requisite conditions are easily obtained if no water is given the crop for a day or two before the treatment. The following morning, before the sunlight-strikes the plants, the house should be ventilated in the usual way, as very little gas will remain in the average house after overnight fumigation.

A disease known as “ stripe ” disease is sometimes found in tomato crops under glass.- The popular name describes the general outward appearance

of the effects of damage by Bacillus Lathy to the main stem of the plant. The perpendicular stripes are usually thin, black, and sunken. Infected fruit has a pitted appearance, or the leaves have small patches of a dark colour between the veins.. Infection should be avoided by sanitary methods, but it is also important to avoid an abnormal state which predisposes the crop to this disease, which is chiefly brought about by an oversupply of nitrogenous food in the early stages of growth. The best treatment for an affected crop is to correct this condition by administering potash. One or two ounces of sulphate of potash per square yard should be given, and repeated' if necessary after an interval of three or four weeks.

The outside tomato crop will require light cultivation occasionally to destroy weeds, the removal of laterals from the axils of the leaves before they much exceed i in. in length, and tying to their support of wires or sticks every foot or so. In some of the districts where this crop is grown extensively, growers will have very unpleasant recollections of serious loss last season due to a borer destroying the main stem of the plants z just above the surface of the ground. Many noticed it first when fine plants heavily loaded .with fruit suddenly collapsed. The small caterpillars which were responsible developed into small moths very much like those which attacks the potato in dry weather ; in fact, it has been identified as a species of that pest, and was named Phthorimaea melanoplintha. It has since been found that an earlier name was given to that genus which, , in accordance with the rules of nomenclature, has now been adopted. The scientific name therefore is Gnorimoschema melanoplintha. .

Where tomatoes are grown a careful watch should be kept for any sign of this attack, so that one may learn as much as possible about the habits of this new pest. It will undoubtedly be advisable to include arsenate of lead with the Bordeaux spray generally used on this crop, and, in applying it, to give special attention to covering effectively the base of the main stem, which is the chief point of attack. Two ounces of arsenate of lead paste, or i oz. of powder, should be made into a cream, diluted, and then stirred into the bordeaux, making it up to 4 gallons of spray. To 50 gallons of bordeaux i| lb. of arsenate of lead paste or % lb. of the powder form should be used. In a well-made bordeaux this spray should have good adhesion, especially on the rough surface of the plants in question. If the season is dry the protective covering should be maintained by repeating the application as may be necessary.

The Market Garden.

Of the half-hardy crops sown and plantec. now there is usually a good demand for rock and water melons ; also the area in ridge cucumber crops could also be extended with advantage where a light, moist, rich soil in a sheltered position is available. Seed of water-melons may be drilled in rows 9 ft. to 10 ft. apart, and thinned to 2 ft. or 3 ft. apart in the row. For the others mentioned 5 ft. or 6 ft. between the rows would generally be sufficient. They should be thinned to 12 in. or 24 in. apart in the rows. A heavy green cover-crop turned under in good time to decay before . planting, or a good dressing of well-rotted farm manure, and 2 cwt. or 3 cwt. of superphosphate to the acre, would usually be advisable.

Hoeing and thinning seedling crops should be attended to promptlyIn the cooler districts a sowing of Swedish turnips made in the month of November makes a useful addition to the supply of winter vegetables.

Crops of asparagus and rhubarb are sometimes harvested over a long period to the detriment of the plants. This is usually unsatisfactory, and it is best to discontinue gathering these crops when berry fruits and summer vegetables, such as peas, are on the market. From established crops sticks may be gathered for a period of about eight weeks, after which a dressing of manure should be given and the plants encouraged to make vigorous

growth that will put them in condition to produce a crop of good quality the following spring. .Bright, tender, and well-flavoured produce can only be obtained by giving the plants generous treatment.

The Homestead Garden.

New growth on flowering climbers and rambler roses should be carefully arranged, and neatly tied in, superfluous growth being checked by nipping out the growing point.

When spring-flowering bulbs begin to crowd, as they often, do after being undisturbed for four or five years, they should be lifted as soon as the foliage matures, and ripened off in a shaded, airy place ready for replanting. Now the rush of spring-time operations is easing off, and frames and boxes have been emptied to some extent, there will be room and time for sowing seeds of late annuals, also biennial and perennial herbaceous plants. ;

-W. C. Hyde,

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