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.