HORTICULTURE.

New Zealand Journal of Agriculture, Volume XL, Issue 6, 20 June 1930, Page 426

HORTICULTURE.

Diseases and Pests of Small-fruits.

Plantations of this class are frequently found infested with diseases and pests. To control such attacks and improve the crops demands careful study now and energetic action in the very near future. Many specimens are received of raspberry-cane infected with rose-scale, wilt disease, leafspot, bud-moth, and anthracnose ; also currants, gooseberries, strawberries, and loganberries with .some of the same or similar troubles. Good crops of a fine sample may only be grown where an understanding interest is taken in these fungous and insect parasites, in addition to good cultural treatment, as was suggested in last month’s notes.

The best time to attack these troubles is in summer-time as soon as the crop is gathered. Raspberry and loganberry canes should then be cut off at the surface of the ground and carried out and burnt, thus disposing of what is generally a large mass of material that is more or less infected. To leave stubs 3 in. to 4 in. long at this pruning is a mistake, as such portions are usually in the worst condition of any part of the old canes. With the removal of these old canes and young weak canes that are unprofitable the remaining growth is exposed to the air and sun to ripen, and may be easily given at once a series of effective chemical sprays to clean them up or prevent the attack of disease. Strawberry-beds may then have the old infected foliage mown off and burnt. The new autumn growth may afterwards be sprayed to destroy the spores of leaf-spot and brownrot. The performance of summer pruning of currants and gooseberries provides similar opportunities for effective autumn spraying.

Where this treatment has been given in a thorough manner and the bushes have been properly winter-pruned and well manured, the prospects of a good crop should be very bright. However, as the .bushes and plants commence to make new growth in the spring they should be given suitable spray treatment and carefully examined occasionally and any new developments noted. Where the summer treatment has been omitted the spray treatment now and on until fruiting-time will be the more urgent. Most of the fungus diseases may be controlled by applying bordeaux 4-4-40 as soon as growth commences, and repeating it, as may be necessary, at intervals of about two to three weeks. For the control of bud-moth of raspberries and loganberries arsenate-of-lead powder, 1 oz. to 4 gallons (f- lb. to 50 gallons), should be added, first working it up with a little water into a cream before adding it to the bulk of the spray. This little caterpillar spends the summer feeding on the receptacle of the fruit, where he does little damage, but after hibernating in the ground he emerges in spring to climb the canes and burrow into the buds. The damage thus caused is sometimes extensive, and may be avoided by a timely application of arsenate. The very common borer of black currants and gooseberries is ■at this season hibernating, and does not emerge until midsummer, when it does so in the form of a moth. Arsenate sprays would then be beneficial, but for .the present the only check available is to cut out the old wood and burn it with the larvae it contains.

The rose-scale, so common on raspberry-canes, is most effectively controlled by cutting low and burning the old wood in summer, thus reducing the autumn brood. In spring-time as soon as the young insects appear they may be readily destroyed by spraying with a good contact insecticide such as Black Leaf 40, using 1 part to 1,200 parts of water (1 pint to 150 gallons). It is very important to first dissolve 3 lb. to 4 lb. of good soap to the 100 gallons of water before adding the nicotine.

The Indoor Tomato Crop.

Tomato-plants now being raised for glasshouse planting should be well aired at all suitable opportunities. To rush them up big and soft gives a false appearance of vigour, and when planted out they are an easy prey to a cold snap. This plant demands a dry buoyant atmosphere, ■ and this should be given whenever possible without chilling them. The plants are then perhaps ' not quite so big,. but well rooted and hardy a condition most favourable for resisting unavoidable, low temperatures or any other troubles they may have to meet.

The soil under glass is sometimes allowed to become “ bone dry ” during the winter,' and plants are sometimes planted out with the soil in such a state or nearly so. This is a serious mistake. In such a —in fact, generallythe land should be thoroughly irrigated some time before planting takes place, so that all stickiness may disappear before that operation. If the plants are then firmly set in open furrows they may easily be given the little further watering required before the weather warms. When planting this or any other crop carefully scrutinize every plant and reject every one that is weak, diseased, or abnormal in any respect. It is only in this way that a strong even crop may be grown.

The Market-garden.

The cost of manures and the scarcity of those of an organic nature demand careful consideration if they are to be used with economy and best effect. It is not uncommon to find them used to excess ; heavy green crops or dressings of stable manure are turned in annually, and the soil becomes overcharged with humus and nitrogenous matter. If the land is heavy and not very well drained, the position may then become serious. A heavy attack of collembola mites and millepedes feeding on the roots are the least of the troubles which threaten the crop. Unless the land is very light or .deficient in humus a heavy dressing of organic manures once in tirj'ee years should be sufficient. This should be supplemented by phosphates, and artificial fertilizers used during the intervening period. Immediately after the heavy dressing cabbage, cauliflower, leeks, and green crops generally may be grown, followed later by deep-rooting crops such as carrots and parsnips, and these again by shallow-rooted crops such as potatoes, onions; tomatoes, and salads. By observing some such rotation the resources of the land are exploited most economically, and disease starved out by the crops which follow being generally resistant to the troubles which affected those which preceded them.

Tn the middle and northern districts of the Dominion hardy vegetation will commence to make new growth during the coming month, and on land that is well drained a start may be made with the new season’s planting operations. Plants of lettuce, onions, cabbage, and cauliflower held in winter beds may be set out, and pickling shallots, garlic, rhubarb, asparagus, and early potatoes planted. Sowings may be made of asparagus for planting out next spring (to be started early, so that good big plants may be obtained), early peas, broad beans, early turnips, cabbage, cauliflower, spinach, and salads ; also onions in the drier districts where spring sowing is practised. • • ' '

Mushroom-culture.

Numbers of inquiries are being received regarding the cultivation of mushrooms, and they are evidently becoming a popular vegetable. Those who purpose to grow the plant should remember it is a saprophytic fungus requiring humid conditions in a temperature of 50° to 65° F. Under natural conditions these exist during the autumn months, and an old pasture completes the necessary requirements. . Such a pasture may be planted with small pieces of the plant—known as mushroom spawn—and a crop may be gathered without much trouble. In that case the method would be to remove a piece of turf about 1 ft. square, also 4 in. to 5 in. of soil from below it. In the hole place a quantity of moist fermenting stable manure that has been specially prepared, and in the centre of this a piece of spawn about the size of a small hen-egg. Firm it well with the foot and replace the turf, beating it down as firm as possible. This may be done any time during the summer, but the material should not be allowed to dry out.

Under artificial conditions the fungus may be grown at any season of the year where the necessary conditions are provided. Sheds and old mines are often mentioned in literature on this subject, as it is under such conditions that the necessary temperature and humidity may easily be obtained at all times, and the absence of light is no detriment to this plant, which obtains its nourishment from decaying vegetation. In the open, low temperatures have to be avoided, and under glass high ones would be just as detrimental ; but where ample ventilation is provided cucumber - houses could be used for the purpose, and in some cases a crop might be grown on the ground beneath the plant-stage of a glasshouse.

Experiments have been carried out with other materials, but so far nothing has been found equal to strawy stable manure as a medium for growing this crop. The material must be brought to a state that is moist and evenly fermenting throughout, as in the making of a hotbed. It may then be made up into beds of a convenient width and any length, and packed firmly to a depth of about 12 in. When the heat has subsided to a temperature of 70° F. the material should be spawnedthat is, planted. When the plants have commenced to run and a mould-like growth has developed (about seven to fourteen days after planting) the bed should be covered with an inch or two of fine light soil that has been passed through a sieve, and made firm with the back of a spade. This soil should be kept moist by watering from a can with a fine rose. In six weeks the beds should commence to crop, and may be expected to continue to be profitable for three to four months. The material should then be removed, and it is most valuable as a manure for the garden or compost heap. Where sheds are used the beds are sometimes made on boarded tiers about 3 ft. one above the other.

The greatest cleanliness is necessary for growing the crop successfully, as this parasitic plant may easily become a victim of other parasites and great loss be incurred through disease. Adequate ventilation is also necessary, and it must be carefully regulated to avoid temperatures that are either too low or hiuh. T .. ' ...

W.C. Hyde,

Horticulturist, Wellington.

Importation of Fertilizers in 1929-30 : Correction.- With reference to the statistics published in last month's Journal, the Customs Department advises that owing to an error in description in the import entry an amount of 700 tons of Egyptian phosphate, valued at £2,391, imported at Invercargill, was stated as phosphate not otherwise specified,” from the United Kingdom. The relevant figures in Tables 1,2, and 3 on pages 339-40 of the Journal should be amended accordingly, the total importation of Egyptian phosphate becoming 1,000 tons, value £3,415.