When the dodder is too widely distributed throughout the field to permit of this treatment, the only course is to plow the field at once, and to grow cultivated crops for two or three years. It is believed that no variety of dodder produces seed freely in the eastern states, and that the hay made from the first crop of alfalfa or red clover will not contain any seed of this pernicious plant.
The Seeding.—When alfalfa has become established on eastern farms, the difficulties in making new seedings will be smaller. The experience of growers will save from mistakes in selection of soils and preparation of the ground, and the thorough inoculation with the right bacteria that can come only with time will do much to insure success. The unwisdom of making seedings in ground filled with grass and other weed seeds will be appreciated. It is quite probable that much successful seeding will be made in wheat and oats, where the alfalfa is to stand only one or two years. These practices are not for the beginner. His land is not thoroughly supplied with bacteria, and every chance should be given the alfalfa.
If there are no annual grasses, such as appear so freely in some regions in mid-summer, spring seeding is excellent. A cover crop is then desirable, and nothing is better for this purpose than barley at the rate of 4 pecks of seed per acre. In all experimental work 25 pounds of bright, plump alfalfa seed per acre should be sown. The seeding should be made as soon as spring comes, the barley being drilled in, and the seed-spouts of the drill thrown forward so that the alfalfa will fall ahead of the hoes and be covered by them.
Seeding in August.—Much land is infested with annual grasses and other weeds, and in such case seedings should be made in August, as described in Chapter VIII.
Subsequent Treatment.—If the alfalfa plants find the bacteria at hand, they will begin to profit from them within the first month of their lives. A large percentage of the plants may fail to obtain this aid in land which has not previously grown alfalfa, and within a few months they indicate the failure by their light color, while the plants liberally supplied with nitrogen through bacteria become dark green. Where there are no bacteria, the plants turn yellow and die.
There are diseases that attack alfalfa, causing the leaves to turn yellow, and when they appear, the only known treatment of value is to clip the plants with a mower without delay. The next growth may not show any mark of the diseases.
Curing alfalfa at the Pennsylvania Experiment Station.
When alfalfa is seeded in the spring on rich land, a hay crop may be taken off the same season. If the plants do not make a strong growth, they should be clipped, and the tops should be left as a mulch. The clipping and all future harvestings are made when the stalks start buds from their sides near the ground. This ordinarily occurs about the time some flowers show, and is the warning that the old top should be cut off, no matter how small and unprofitable for harvesting it may be. The exception to this rule is found only in the fall. An August seeding may make such growth in a warm and late autumn that flowering will occur, and lateral buds start, but the growth should not be clipped unless there remains time to secure a new growth large enough to afford winter protection. This is likewise true of a late growth in an old alfalfa field.
Owners of soils that are not well adapted to the alfalfa plant will find top-dressing with manure helpful to alfalfa fields when made in the fall. The severity of winters in a moist climate is responsible for some failures. If the soil is not porous, heaving will occur. A dressing of manure, given late in the fall, and preferably during the first hard freeze, will prevent alternate thawings and freezings in some degree. The manure should have been made from feed containing no seeds of annual grasses or other weed pests.