Part 3

For northern climates, greenhouses are practically required. Canneries or other large growers, have wide houses similar to those used for winter maturing crops. A market gardener may have a little house of 10´ × 20´ to 20´ × 60´ or larger as needed. If one does not object to some inconvenience and discomfort, a hotbed may be used--heated with hot water or electricity, or as in years past, with fermenting manure. Cold frames may be covered with glass sash as in the case of hotbeds, or cloth may be used. There are also materials consisting of wire cloth filled with cellulose film. Special mats of straw or of quilted burlap may be used for extra cover and large growers often employ coarse manure, straw or marsh hay.

Many a tomato gets its start in life in a small flat in a kitchen window--perhaps, in a cigar box. Such seedlings may then be carried forward in hot bed or cold frame.

Beds, Flats and Pots

Growing plants directly in ground beds in the greenhouse and directly in the soil in the hotbeds or cold frames, is rather common. However, the use of flats or plant boxes in plant growing offers a number of advantages as compared with planting in the bed. Transplanting can be done at benches under conditions of comfort and convenience which make for efficiency. Moisture can be more precisely controlled and flats can be shifted if some plants grow faster than others. Plants can be moved with more dirt on the roots, and this is a great advantage when plants are sold and hauled some distance, though, of course, pulled plants are handled more cheaply. On the other hand, the first cost, and the maintenance and storage of the flats must be considered. Flats may be set on the ground in the greenhouse without use of benches.

Flats are of many dimensions, ordinarily six to ten per sash or about 18 × 22 inches or 13 × 18 inches outside measure. They may be made of lumber from used boxes, but they ought to be uniform in size and made to fit beds without loss of space. The more durable kinds of wood, cypress or chestnut are preferred. Some growers make the bottoms of the flats of square-mesh galvanized screen (hardware cloth), about five or six meshes to the inch. This allows roots to penetrate the soil of the beds, permits root pruning by shifting, and there is no wooden bottom to rot.

Some growers use clay pots for plants which are receiving special care. Their cost is an obstacle though they are used repeatedly. Such pots also hold less soil for the area occupied than flats or square dirt bands.

Paper pots are used to some extent. Organisms decomposing the paper may use and so render unavailable some of the nitrogen of the soil thus hindering the growth of the plants. This may be corrected by seeing that abundant nitrogen is present in the soil either when made up or by later application of nitrate sowed upon the soil while plants are dry or applied in solution in watering.

Dirt bands of veneer are used and are very satisfactory. Blocking as practiced by many growers is a cheap and effective way of attaining much the same results.

The Blocking System

When the cold frame is prepared for the last transplanting, two inches of fairly well-rotted manure is laid down and two or three inches of prepared soil is placed on top. Plants are set about four inches apart each way. About a week before field setting, a butcher knife, or a hoe which has been straightened and sharpened, is run between rows both ways. This cuts the roots whereupon the plant at once begins to form new feeders within the block thus reducing, to some extent at least, the damage which might be caused by transplanting. The method is also used with flats.

Soil

Soil for plant growing should be free of disease and nematodes, friable, not readily forming a crust, receiving and retaining moisture well, but drying off quickly on the surface after watering and well supplied with nutrients. A sandy loam base with good humus content is desirable. It may be prepared, beginning a year or two ahead by growing and plowing under well fertilized green manure crops. Or a compost heap may be prepared with successive layers of soil and manure or other humus making material. In either case, it is usually mixed a time or two by shoveling over or by passing through a shredding machine or a coarse screen.

If trouble is likely to be experienced from damping-off fungi, the soil may be heated to 200° F. and held there for an hour, using oven or electric or steam sterilizer. Seed may also be treated with red copper oxid or semesan.

Seed and Seed Sowing

Tomato seed runs about 125,000 to 150,000 per pound. An ounce of seed is usually depended upon for plants for an acre. For growing seedlings, seed may be sowed up to 100 or more per foot of row. For a maximum number of strong seedlings from a small amount of seed, thinner sowing is desirable. Rows are usually about two inches apart, and a quarter of an inch is sufficient cover. The seedlings break ground in a week or ten days.

Uniformity of depth of rows and of covering is important. Otherwise, seedlings will come up unevenly and there will be considerable waste.

Care of Seedlings

Water and heat should be provided to permit a steady and moderate rate of growth in plants. Over-watering and high temperature yield soft and spindling plants and also plants that are overgrown and that are liable to severe checking before field setting. Under-watering and low temperature give stunted plants. The thermometer at the earlier stages of growth may well stand around 70 to 75 degrees by day and 10 degrees lower at night. A reasonable range of temperature and moisture gives opportunity for the skillful grower to forward or retard his plants as seems best. Great care should be exercised to water evenly. It is necessary to watch the plants constantly to detect the slightest variations in growth. The watering may then be modified and even progress insured.

Ventilation finds its chief significance as a means of controlling temperature and humidity, though actual change of air may be a factor.

High soil moisture, high humidity, high temperature, and faulty ventilation, all favor the ravages of the various damping-off fungi mentioned above which cause little plants to rot off near the ground.

Transplanting

The main advantage of transplanting plants before they are set in the field is to give them increased space, or, in other words, to conserve space in greenhouses and frames. Other advantages have been claimed, but in many instances the gains have resulted from more space rather than from the actual shift. Transplanting checks growth through breakage and disturbance of the root system. Loomis[14] finds that "the immediate effect of transplanting is a reduction in the water supply, and the immediate and long-time results are dependent upon the severity and duration of such reduction." Transplanting has little effect upon very young plants and a shift at the age of six or eight weeks checks the plant about as much as two earlier transplantings. The tomato falls in the group of plants that stand transplanting well, roots being rapidly replaced. Transplanting breaks roots and so results in the growth of branches which are shorter than the members of the old system. The new system is accordingly less severely damaged in later transplantings.

To insure efficiency, the work of transplanting merits careful attention. Carelessness as to details means loss through unevenness of plants. For example, if soil is not carefully packed at the edges and corners of the flats, irregular water supply and irregular growth result. If much transplanting is to be done, it pays to divide up the work, as is done in a factory. Have a good place for doing the work--a warm, light, and comfortable room. Tired workers are not efficient. Spotting boards are of service if properly made and correctly used. Soil should always contain just the right degree of moisture to allow holes to stand open. Care must be taken that the workers in setting plants do not double the roots or close the holes at the top leaving the roots dangling in an open space below.

It is said that a good worker will prick out 10,000 plants per day, though everything must be convenient to accomplish this and many growers regard 6,000 plants as a good day's work.

Pruning Young Plants

Pruning of tops injures rather than helps the plant, for it destroys leaves which are the machines that make carbohydrates, the principal material for growth. Pruning to cure legginess is bad. Proper management of time, temperature and water will provide adequate control and if plants should become leggy, it is better to plant them by laying them down in a trench with a few inches of top above ground than it is to prune them.

Nipping out the growing point with the first cluster of flower buds is sometimes practiced to encourage branching and a heavier yield of early fruit. If this is done, ample space and nutrients must accompany careful management. Otherwise, the plant finds itself with inadequate resources to do a big job.

Hardening

Tomato plants cannot be made frost proof, but low temperature, reduced moisture supply, partial starvation, and crowding all tend to make plants more resistant to cold, to drying winds, to heat, to mechanical injury such as breakage of leaves and stems, and even to cut-worm attacks. Plants can be hardened appreciably in a short time--say a week. It is now generally accepted that moisture control is more useful than reduced temperature as a means of hardening. Starving and crowding are not desirable methods. Plants can be kept on the dry side if glass or other water-shedding cover is available.

Great care must be exercised to avoid over-hardening of tomato plants, for in this way a check in growth is incurred from which they recover slowly, and perhaps never fully.

Much study has been given to the changes in plants which underlie the hardening process, and papers by Harvey, Rosa, Loomis, and others should be consulted in this connection.

Watts[15] has shown that adverse conditions, especially low temperature and water deficiency prevailing at the time when fruit clusters are barely beginning to form, commonly occasion the development of misshapen fruits.

Faithful spraying or dusting with Bordeaux in the plant bed has proved a useful means of forestalling destructive leaf blights which often devastate whole fields.

V

GOOD CULTURE FAVORS GOOD RETURNS

The tomato is not especially exacting as to care after it has been set out-of-doors. It will do business if given half a chance. At the same time, much can be done to favor earliness, good yield and high quality.

Time of Planting

In general, tomatoes are set in field or garden as soon as danger of frost is reasonably past. Suppose May 1st is average date of last killing frost. Growers would make general plantings from May 18th to 25th though, in rare instances, frost might occur as late as May 28th or 30th. The last week of May is planting time over a vast area of the North. Venturesome souls will set home garden plants as early as May 10th, standing ready to replant if necessary. There is little gain in rushing the season too much, however, for the tomato is not only sensitive to frost but it does not thrive under what people call "raw, mean, chilly weather." Such conditions may also be responsible for misshapen fruits. A grower for local market not infrequently risks a share of his plants before safe setting time in the hope that warm weather may give the crop a good start toward early ripe fruit to sell at high prices.

Delayed planting and use of plants that do not start quickly into vigorous growth is the cause of heavy losses in the north, especially among cannery growers. Better quality and heavier yields are attained if the bulk of the crop matures before cool weather in the fall. In the south, it is necessary to get good plant development and a full set of fruit before hot weather which often destroys the blossoms.

Plant Protectors

Many forms of plant protectors are on the market--of paper and of other materials. These act as little greenhouses for the individual plant, protecting against frost and promoting growth. Plants may be set out-of-doors a couple of weeks earlier by their use. The most common forms are of translucent paper reinforced by pasted strips of paper or by wire. The trick is to devise one that is cheap, that will admit maximum light and that will withstand the weather. For tomatoes, they need to be tall, which makes the problem of wind resistance more serious.

For emergencies, opaque cover, baskets upside down or even newspaper may be used. Many a field has been saved by burying the plants when frost threatened, carefully uncovering when danger is past.

Spacing

Untrained tomatoes are set at distances from 3-1/2 feet each way to 7 × 7 feet or even more. The extreme width is found on rich irrigated lands in California where plants make tremendous growth. The closer spacings are found on lighter soils where humus, plant food, and moisture are not too abundant. The variety should also be considered. Sixteen square feet per plant is about average.

Check row planting is common, though it is not feasible where transplanters are used. Wider spacing between the rows than between plants is desirable as it permits later cultivation one way and leaves a better passage for pickers with less damage to plants and fruits. Thus, 3-1/2 × 4-1/2 feet might be preferred to 4 × 4 feet.

Rows for single stem, staked and pruned plants may be as close as three feet and plants may be as close as eighteen or even twelve inches, though some growers contend that two feet is close enough.

Methods of Planting

The essential point in field setting is to pack the soil firmly about the roots, thus establishing maximum contact for moisture absorption. Whatever the method of planting, the aim should be to get the plants from the old home to the new with as little delay and check in growth as possible. For the first-early crop, they should be moved so that "they never know it." With bands, pots or blocking in flats or beds, it is feasible to avoid practically all disturbance of roots.

The tomato will, under ordinary favorable conditions, take hold and grow even if shaken quite free of earth. Plants, however, should be dug loose rather than pulled, to prevent undue breakage of roots.

Plants ought to be watered well some hours before transplanting. Transplanting machines and hand planters of the Masters type give a little shot of water at the root, thus helping to establish contact with the soil. Starter solutions are discussed on page 35. These machines are commonly used for cannery setting and, to some extent, for market tomatoes. Blocked plants can be set pretty fast by hand with much less disturbance of roots. Some manage to set potted or blocked plants by machine, keeping a ball of earth about the roots.

The rows are usually marked out fairly deeply, plants are dropped in fours between rows and it is a very short job to pack soil about the clod of earth in which the plant is growing. Another method is for one worker to make an opening with a spade. A second places the plant in the wedge-like opening and the first steps on the soil to firm it solidly about the roots.

Plants are generally set a little deeper than in the plant bed.

Cultivation

The old idea about cultivation was "the more, the better." More recent experiments notably those by Thompson have shown that little need be done beyond controlling weeds. He found that stirring the soil gave no significant increase in yield over mere scraping sufficient to destroy weeds. It is pretty hard to convince many old time gardeners of this. The value of dust mulch for conservation of moisture has been pretty well discredited by experimental comparisons.

Irrigation

Irrigation is not essential for tomato production in humid climates and is seldom provided except under market garden conditions. Water is occasionally an asset in a dry season and, of course, the grower who waters at such times reaps a harvest in higher prices as well as in increased yield. The advantage of irrigation is especially marked if dry weather retards plant growth and delays maturity of the first of the crop, for the high prices of the early market are involved. Judicious irrigation will sometimes continue production for late fall market. Yet gardeners seldom plan permanent overhead equipment for tomatoes. The movable lines that are now used to a considerable extent serve well for the tomato crop.

The furrow method of irrigating tomatoes is the most common in the West. This plan allows the water to make its way down the rows, slowly soaking in all along the line. The tomato stands drouth better than many of our crops, especially if the soil holds moisture fairly well, either naturally or through a liberal humus content. Excessive moisture is doubtless a factor in causing the plants to run to vine and drop their blossoms. Hence, in western sections, it is customary to water thoroughly just before or just after setting the plants and then to avoid applications until the setting of fruit is well advanced.

Thorough soaking is better than frequent light waterings, as it encourages a better development of root system. An Idaho bulletin suggests three irrigations. Late irrigations tend to delay ripening of fruit, but this object is sought in the late fall shipping districts of California which find their best markets after eastern crops have been nipped by frost.

Irrigation must be handled with care to avoid cracking of fruit, which occurs when soil becomes rather dry and then is heavily watered. Watering late in the season is said to make fruit watery and of poor quality.

Mulching

R. A. Emerson[16] in 1903 reported results of careful comparisons between vegetables that were cultivated and others that were mulched with straw. These results indicate that mulching gives good results with tomatoes, both as to yield and quality. However, frost injury was more severe on mulched plats, and Emerson points out that the mulch should not be applied until the plants are well established.

Mulching is recommended by a good many writers and growers and it seems to be practiced to some extent in Missouri. The advantages claimed are conservation of moisture and clean, fine quality fruit. L. W. Purdum and Sons of Virginia use 4-5 tons per acre of wheat straw, staking their plants and irrigating. They report unusually heavy returns per acre under these methods. The Missouri people apply as much as sixteen tons per acre, making the cover five or six inches thick. The practice of mulching, however, is not common, and the cost will likely prevent its general use.

VI

TO TRAIN THEM UP OR LET THEM SPREAD

Growers attending conventions will often stay up half the night to argue about training and pruning tomatoes and to debate the details of their favorite procedures.

For home garden, the method is strongly commended. Many market gardeners follow the practice and it has gained materially of recent years in New England. Some market reports quote staked tomatoes separately and at a materially higher level than fruit from unpruned plants.

Most of the southern shipping sections follow the practice and it is practically universal in greenhouses.

One way is to drive a stake by each plant tying at several points along the stem with cheap twine. The other plan, recently gaining in favor, is to set posts every 25 feet or so, string a heavy wire on top, and another a foot from the ground. Cheap jute twine is strung between wires and the tomato plants are merely twisted around the string. Tying is not required. Some omit the lower wire, tying a non-slipping bowline loop around the plant near the ground. In either case, plants are kept trimmed to a single stem though occasionally an extra branch is allowed to grow. In southern Illinois, plants are tied to a short stake without pruning.

Pro and Con

The advantages claimed for pruning and training are:

Earliness. High yield per acre. Ease of cultivating and spraying. Ease of picking. No injury from snails and wire worms. Quality of fruit:--size, color, smoothness and cleanliness. Crop finished earlier. Less sunscald.

The disadvantages claimed are:

Many plants required. Reduced yield. More blossom-end rot. Higher cost of labor. Cost and care of stakes and wire.

The validity of each of these points varies greatly with conditions; in fact, the answer to the whole question depends largely upon the location and the ideas of the grower. In trying to reach a conclusion, it is well to realize that training makes certain radical changes in the plant. It loses leaves through pruning, it is supported from the ground, and it is spaced differently. Since the leaves manufacture the basic substance for themselves, and for the rest of the plant, removal of leaves reduces the resources of the plant. H. C. Thompson[17] has found that the root system is reduced about in proportion to leaf reduction. It is fairly clear that single-stem training greatly reduces the yield per plant, and other methods result similarly in proportion to the severity of pruning. When plants are spaced closely enough together the yield may be brought up to that of areas unpruned and unstaked. Idaho experiments indicate that staking alone does not affect the total yield, but that it does favor early maturity under the different pruning systems. The disadvantages of training are largely economic. Will the marketing conditions justify the extra cost of staking and pruning?

Experiments have shown pretty clearly that sunscald, blossom-end rot and cracking are worse on trained plants. Using varieties of good foliage will help the first trouble while uniform and adequate water supply achieved by selection of suitable land, by building humus content of the soil and by irrigation will solve the latter two problems. Thompson found increased yield of early fruit. Other evidence is somewhat conflicting but, in general, it supports Thompson. It is generally agreed that pruned plants yield larger, cleaner and more perfectly formed and colored fruits. Ease of spraying or dusting and of picking is important.

For pruned plants, 3-1/2 feet between rows and 1-1/2-2 feet between plants is about right.

To train or not to train is a question that one must answer for himself as the controlling factors vary too widely--costs of stakes, wire and labor, prices of early tomatoes and possibility of cultivating a more or less fancy trade.

VII

THE ETERNAL BATTLE WITH INSECTS AND DISEASES

The tomato, in most regions, is not one of our most "pestered" crops. Although over thirty diseases of tomatoes are discussed in books and bulletins, most of them are only occasionally serious or are subject to definite control methods. Enemies are generally worse in the warmer climates.

Most home garden tomatoes and many commercial crops are grown without benefit of spray or dust. If trouble arises, county agent or college specialist can usually advise, suggesting methods suitable for local conditions.