Manuring.—It is desirable to keep plants of the tomato which are designed for forcing growing at a moderately rapid rate throughout the whole forcing period. Growth should be strong and robust at all times, yet slow enough to produce close-jointed plants which bear their fruit clusters at near intervals. There is considerable difference in varieties of tomatoes in this respect, and those which naturally bear their fruit clusters close together should be selected for forcing purposes. The manuring of the plants should, therefore, take a form which will be conducive to this strong, vigorous growth, yet not sufficiently heavy to produce plants which run to wood at the expense of fruit bearing.
Ventilating and Watering.—If careful attention is given to keeping the plants in a healthy condition by never allowing them to suffer from overwatering or from becoming too dry, and if sufficient ventilation is given without allowing draughts of cold air upon the plants, much can be done to prevent the development of mildew. If the plants are to be sprayed it should be done once a week or once in ten days, and then only in the mornings of bright days. Ordinarily, however, the atmosphere of the house should be kept dry rather than moist, as a very moist atmosphere is liable to produce a soft, succulent growth, which brings on a disease known to gardeners as œdema. This, however, can be prevented by care in keeping the house rather dry. The temperature of the house, too, should not be allowed to fluctuate through too wide a range. The night temperature for tomatoes should range between 65° and 68° F., while the day temperature should run from 70° to 80° F.
Varieties for Forcing.—The comparatively limited use of tomatoes for forcing purposes in this country has not resulted in the development of many sorts especially suited for this purpose. The Lorillard is the one American sort which is now almost exclusively confined to this use, and it is perhaps more generally cultivated in forcing houses than any other single variety.
The Tomato as a Field Crop for Canneries.—Owing to the fact that in canned tomatoes it is difficult for the average consumer to note any deficiencies in the appearance of the original fruit, many labor under the delusion that any variety will answer for this purpose. This is a mistaken idea, as quality in canned goods is now an important factor, and it is quite as necessary that a good quality of product should be used for canning as for growing for the early or general market, although from the field side it is natural that tonnage should be a primary consideration.
In the matter of varieties, as in the case of early tomatoes, too much dependence should not be placed upon the name or upon the fact that a neighboring farmer secures good results from a given variety. There are so many variations in the character of soils, even in the same locality, which exert an influence upon the size and quality of crop that the best variety is usually one that is, in part at least, developed by the individual grower. The main point is to select varieties that produce large, smooth, solid fruits, which do not remain green or crack on the shaded side near the stem. Those which possess size as their chief characteristic are frequently of poor quality, as they are likely to possess large seed cavities and to ripen unevenly.
The conditions in some sections are such as to prevent the canners from making as much distinction between good and poor varieties as they would like. Canneries are in a measure obliged to receive all that come, unless they can control absolutely the land upon which the crop is grown. The variation in the quality of the crops of different farmers will make a difference of from 25 to 40 cans on a ton of fruit, or from 6 to 10 per cent—a very considerable item. In good seasons and with good fruit 400 cans may be regarded as the maximum number to be derived from a ton, though late in the season, and with poor varieties, as already stated, the pack from a ton is very much less. The interests of the grower and the canner are really identical in this regard. An improvement in the quality of the fruit will result in an improvement of the canned product and a consequent increase in the price of both the raw and manufactured products. Less expense is involved in growing suitable plants for cannery purposes than for other crops. This is due to the fact that earliness is not so important a factor as it is in the market garden crop.
Fertilizing and Cultivating the Soil.—In manuring and fertilizing, the character of the crop and the season of its growth should be remembered. Hence, recommendations that were made for an early crop do not apply in all cases except perhaps on the poorer classes of soils. In the first place, the plants are not put in the soil until summer, when the conditions are most favorable for the rapid change of organic forms of nitrogen into nitrates, and thus, if the soil has been manured or is naturally rich in vegetable matter, the additional application of nitrogen in immediately available forms is not so important. In the second place, the object of the growth is not early maturity, but the largest yield of mature fruit.
Setting and Cultivating the Plants.—The plants should be set from 4 to 4½ feet apart each way and cultivation should begin immediately. The first cultivation should be deep, in order to conserve the moisture, and each subsequent cultivation shallower, in order not to destroy the roots, which will fill the soil as soon as the plants reach maturity. The crop in good seasons should begin to ripen in August, and picking will continue from that time until the last of September.
Cost, Yield, and Value of Crop.—The cost of production per acre is much less for fruit for canning than in the case of early tomatoes, the chief difference being in the production of the plants. The several items may be classified as follows:
Cost of growing an acre of tomatoes for canning: