Vegetables, Small Fruits, and Flowers.

New Zealand Journal of Agriculture, Volume 56, Issue 5, 20 May 1938, Page 370

Vegetables, Small Fruits, and Flowers.

Tomato Crops under Glass.

WHERE the annual tomato crop is grown each season on the same land for some years it- is not surprising that difficulties often arise. Many of them are due to cultural problems which may occur anywhere, but the more serious are due to the strong establishment of diseases and pests which find this crop a favourite host. They are dealt with economically and effectively only by maintaining a high standard of cleanliness and observing a strict method of sanitation not only inside the houses, but outside in the vicinity— the toolshed, ■ and, . in fact, . about . the whole premises. - It is only when this is done that one may expect satisfactory results from chemical remedies. No grower is successful over a long period unless he carries out. these principles rigorously. In some of the warmer districts the crop in the unheated glasshouse is planted towards the end of July, but more often planting out under such conditions is done towards the end of August, and usually that is soon enough. The cultivation of the land and the fertilizers applied are usually satisfactory, but the maintenance of a supply of humus and the application of sufficient water are very commonly neglected. The diseases in the crop resulting in the past from the excessive use of stable manure led to the present fairly common state of a shortage of humus. The soil readily becomes dry and dusty, and lacks that active bacterial action which is recognized as a characteristic of fertility. Watering Necessary. In a light soil with an open .subsoil considerable amounts of organic matter are required to maintain that condition. With a higher water-table and a heavier soil humus is consumed less rapidly. As land under glass does not receive the advantage of winter rains it is important to supply that deficiency by wetting soil and. subsoil thoroughly three or four

Contributed by the Horticultural Division.

weeks before planting takes place. More than one application may be necessary to do this properly, but it is important that it should be done and the land allowed to warm up to a temperature of about 55 degrees F. before planting is commenced. Little watering will then be required during the difficult springtime period, and steady growth is less likely to be impeded. Raising Seedling Plants. Tomato seed for planting out under glass towards the . end of August should be sown now-; another sowing for planting outside towards the end of October should be made in August. It is unsatisfactory to hold over surplus plants from the first sowing for. outside planting at the date mentioned, as the plants will be stale and stunted, and cropping retarded as a result. • The main requirements to obtain good plants are a satisfactory compost, sufficient heat, and close attention to ventilation, although

ample light should by no means be forgotten after germination has taken place. . Where the compost is sterilized, turning and mixing is usually quite well done before filling the boxes. In other cases this necessary preparation is often neglected. By turning a heap of compost as soon as seedling weeds germinate the weeds are destroyed, and successive crops of the same kind are dealt with in a similar manner. The . ingredients, too, are well mixed. Fungi and insects are also destroyed by these operations, and the chemical condition, of the compost is improved. Suitable Temperature. A suitable temperature for raising these seedlings is 60 degrees F., with a limit either way of 55 degrees and 65 degrees F. They are raised in a propagating-house heated by means of hot water or electric cable, on a hotbed of composted stable manure in a glasshouse, or, later, outside in a warm sheltered position, or the frame

in a glasshouse is heated by means of oil burners. The young plants must be watered sparingly with tepid water,' but they should never be allowed to become dry. , Ventilation should be given on all suitable occasions. This is, perhaps, the most difficult requirement to supply because of the demands on one’s time at a busy season of the year, but it, is fundamental to success and will save much work and anxiety later. Diseases indirectly caused by. overheating and chilling plants are probably the commonest source of trouble in growing this crop. Examination of Produce in Storage. Potatoes, onions, pumpkins, &c., in storage should be examined at fairly close intervals at the beginning of the storage season to see that all is well and to ■ obtain early intimation of whether deterioration is going to occur. Suitable varieties which are well cured and free from disease should not give much trouble in being stored without loss in a shed in which the temperature is fairly even and free from violent fluctuations. Produce of less reliable quality will require close supervision, but in either

case good ventilation, whenever it can be done without resulting in extreme temperatures, will lengthen ' the storage period as long as possible. This is most important during the early part of the storage period. Early Vegetable Crops. The preparation of the land for planting early, crops in July and asparagus and rhubarb, &c., during August should be continued during mild dry weather. In many districts such conditions are rare at this season, and every advantage must be taken of the periods when they do occur. Cultivating the land when it is frosted or wet is bound, to cause trouble, and in most cases it will be serious. Control of Slugs and Snails. In summer, . when growth is plentiful, the browsing of slugs and snails is not so serious as during winter and early spring, when the plants are small. ' . They may then do extensive damage in a very short time if not checked. Bluestone (copper sulphate) in any form and in the smallest quantities is intolerable to these creatures. If it is dehydrated and mixed with lime hydrate (slaked lime) at the rate of i part to io and thinly distributed

with a “ duster,” or is finely ground and mixed with kainit at the rate of i part to 20 and distributed at the rate of i oz. per square yard it is very effective. In addition, they will not touch anything which has been sprayed with Bordeaux. Alum is another effective slugicide. In solution or distributed thinly as a powder it may be used freely among growing plants without damaging them. A new and effective remedy is “ Meta.” One stick finely ground- and mixed with- a quart of bran and distributed thinly is a popular remedy ” in Europe just at present. At night in warm humid weather these creatures are most active, and treatments, generally, are best given then or during the afternoon preceding such periods. Pruning Trees and Shrubs. Pruning is done at different seasons with various objects, as, for instance, in early summer when disbudding and shortening new wood ■is done to some extent with the object of directing the growth of a plant, or in late summer when . laterals may be shortened to encourage the formation of flower-buds on trees which carry their blossoms on “spurs” on the old wood. At this

winter period pruning is an important operation among deciduous trees and shrubs. Evergreens of that class are generally more tender, and are usually given this attention towards the end of winter or in early spring, especially when heavy cutting back is necessary. Last month’s note closed with a description of pruning treatment suitable for most kinds of trees and shrubs when young and at the time of planting outtreatment which is of the greatest importance, as, if early training is neglected or on the wrong lines, little can be done to improve it later. Use Sharp Tools. Trees and shrubs which are established and on their way to maturity should be carefully looked over at this season, and branches which are inclined to crowd too closely or cross the centre of the tree and chafe others should be removed entirely. The grower should make the cut close up and ’ flush, using sharp tools (so that it may be. smooth), and dressing with hot tar, paint, or bitumen emulsion all wounds of any size. When this is done with care it strengthens the frame of the plant, enabling it to carry better a weight of fruit if necessary, and to withstand the force of high winds. The pruning admits to all parts sufficient light and air for the desired growth of buds and foliage. A few plants which have soft, spongy wood with large vessels, such as the grapevine, are best pruned in a way which leaves a stub extending beyond the bud from which growth ' is desired. The following year, or when the stub is dead, it should be removed flush with the living wood. This is especially important on those rare occasions when cuts are made into the old wood. Trees and . shrubs which have reached maturity and from which flowers and fruit are expected are often pruned systematically each year at this season with a view to the abundant renewal of wood of the fruiting type. This attention is usually reserved for some of the more useful hybrids. Hydrangeas and roses, which carry the bloom on new wood, have last season’s growth ' thinned drastically by the complete removal of weak and crowded wood, and the remainder is shortened back to a few buds, the last of which points in an outward direction. It is from the ensuing new growth from these buds that next season’s bloom is to be expected. Minor adjustments to this treatment will be required for certain varieties and for plants growing under certain conditions. Late Pruning. In localities where hard frosts may be expected during the springtime late

pruning is practised so that new growth is delayed to avoid injury from that cause. Hydrangeas which are in a sunny position where summer bloom will get burnt, may be pruned hard and late, so that the main flowering period will be deferred until the autumn, when the conditions are more favourable. Roses of the class known as Pernetiana, hybrids originating in the yellow Austrian brier, resent having the young wood shortened back much, and heavy thinning is practised, and only the unripened end cut from the young wood. The effect is to induce strong new growth from the base of the plant. Black-currant bushes and gooseberries flower and fruit on last season’s growth of wood if it is moderately vigorous and well ripened. When pruning plants of this class at this time, weak wood and old wood is cut down to the bud at the base, from which new growth may be expected next season which will flower and fruit the following year. Wisteria, Actinidia chinensis (Chinese gooseberry), and others which flower on spurs on . old laterals merely require the elimination of any strong growth which may upset the design to which the plant is being trained and such attention as may be required to keep the spurs in vigorous condition, as, for instance, shortening them to a moderately strong wood bud with a view to attracting growth to that section. The study and practice of pruning is one of the main factors in the successful management of very many plants. Spotted-wilt Disease of Dahlias. This trouble has been unpleasantly familiar in some tomato crops during the last decade. In one garden in the Gisborne district where . rather a large collection of dahlias is grown 75 per cent, of the plants is affected, although one previous season the percentage attacked was very small. The symptoms in this instance were more or less ‘ circular lines on the upper surface of the mature foliage, the rings being anywhere between about J in. and 1 in. in diameter. Severely infected plants showed a dozen or more rings on an individual leaf and at times associated with yellow blotches. Most plants showed signs of diminishing vigour and the blooms were of less than normal size.” . , This trouble belongs to that rather mysterious class known as virus diseases, the causal principle of which eludes observation, but whose presence is demonstrated by cross inoculations. Identification is often difficult; as the symptoms vary widely according to the kind of plant affected, its age, and the conditions under which it is growing. The disease was first observed in crops

of tomatoes growing near Melbourne in 1915-16, and has now been recorded from all of the States of Australia and over a wide area in Great Britain and California. Spread by Insects. Tests indicate that it is not seed-born, not spread by soil infection, and not so readily transmitted by inoculation as other virus diseases. The most important agent in the natural spread is by means of species of thrips insects, which must have been fed on an infected plant during the larval stage to transmit the disease. The evidence of plants recovering from the trouble is very slender. The trouble is unique, in that it has a very long list of host plants, which includes as many as fourteen different plant families in England and as many as nineteen in California. The species of Composite and Solanaceae susceptible are specially numerous. Other plants are lupin, broad bean, Iceland poppy, arum lily, nasturtium, and antirrhinum which are among those likely to carry' the trouble over from one season to the next. Good varieties of perennial plants, such as dahlias and chrysanthemums, which are propagated vegetatively, may readily become a serious loss after infection, as roots and tops must be destroyed. Infected chrysanthemums sent to Cheshunt Research Station are described as “ showing brown areas on the leaves, small lesions on the stems, and withering of the flowers.” In the circumstances, the best means of control is to keep a sharp look-out for any sign of infection and carefully to destroy infected plants as soon as they are observed, taking care to avoid carrying infection on hands or implements, &c. Insect-pest control ' must also receive attention, especially thrips, which seem to be chiefly responsible. New Gardens. Where new gardens are being made or additions and alterations to old ones are being carried out, . the preliminary work should be done as soon as possible and as weather permits, so that ample time may be afforded for cleaning and setting the land before sowing grass-seeds and setting out trees and shrubs in August and September, which is about the limit of the - “ planting season ” in most localities. Attention to drainage and repairs of paths and roadway may be given now as required; nothing about the homestead possibly contributes more to the appearance and efficient working of the place. —Wm. C. Hyde, Horticulturist, Wellington.