“Where a newly seeded alfalfa field shows evidence of quite general dodder infection, it is useless to attempt to eradicate it, and the field should be plowed up and planted with some hoed crop for a period of years. Old fields that have been thoroughly infested will probably be more economically treated in this manner than in any other. In newly sown fields, one of the most effective methods is probably hoeing over the spots where the dodder appears, going over them once in two weeks and allowing nothing to grow on them until the dodder seed is germinated. A modification of this method has been used successfully by spading in fields where the colonies of dodder were seen, raking out all the tops, roots and branches, adding a little straw or hay and burning the mass, and then keeping the spot thoroughly hoed for a season. For fields where the colonies are small and scattered, this method of hoeing and shallow cultivation is probably the most practicable, as it helps to secure the early germination of any seeds that were left in the ground, and also kills them as soon as they are germinated. If the seed has developed, one must be careful not to spade it in too deep, as it may retain its vitality for some years if left covered in the moist soil.
“Burning has been recommended by some, raking the dodder vines and what is left of the alfalfa to the center of the colonies, putting brush or straw with it, together with some fine, light wood or chips and sprinkling with kerosene, so that the alfalfa plants will be burned close to the ground. This is necessary from the fact that the little coils of dodder close to the crown of the plants will retain their vitality and grow after a very severe burning, providing the alfalfa which is above the ground is not killed also. The most difficult problem to be confronted in killing out dodder where it has become established, arises from the fact that if these little coils which wind themselves closely around the plant are not killed or removed, the dodder will spread from these and make a new growth. Many experiments have been made with chemicals, but none of them have proved wholly successful, from the fact that these little rings were not destroyed. All the rest of the plant was killed and the production of flowers and seed prevented; but as these little rings were not killed, the dodder began growing again and continued to grow throughout the season.”
LEAF SPOT
Leaf spot is a very peculiar disease and, fortunately, not common in this country. It has been known in France since 1832. In 1891 it was destructive in Iowa alfalfa, the loss in the neighborhood of the experiment station being estimated at 50 per cent. In reference to this infliction the Iowa station, among other information, printed the following:
“Any time after the plant has attained a growth of four to six inches from the seed, but most commonly after the first year’s growth, there appears upon the upper side of the leaves small, irregular brownish spots, which enlarge to about one-sixteenth of an inch in diameter and extend through the leaf to the under side, turning all parts brown. When many spots occur on the same leaf the whole leaf soon turns yellow and falls off. This falling of the leaves and the natural loss in vigor, due to the diseased condition before the falling, constitute its great damage. Frequent cutting of the crop materially prevents the disease.”
In eastern states farmers report that there are frequent patches in their fields where the leaves turn red and the plant dies. The probable explanation of this trouble is “wet feet,” which alfalfa will not abide. Don’t expect to get a crop of alfalfa from a field in which water is near the surface. Drain it or use another field.
ROOT ROT
A disease peculiar to portions of the southern states is called “root rot,” and similar to the root rot found in cotton fields. The alfalfa dies in spots, these spots widening in circular form. This is a fungus that spreads only in summer. The only means of eradicating so far (reported by the Texas station) is the application of common salt and kerosene. It has not proven a serious annoyance.
GOPHERS AND PRAIRIE DOGS
Gophers and prairie dogs are great pests in some parts of the Middle West, and about the only successful means of combating them is poison. The state of Kansas has, probably more than any other, made a systematic effort to destroy its gophers and prairie dogs, by liberal appropriations and a field agent to supervise the work to be carried out under provisions of law by local officials.