“The rapidity with which the pest spreads makes it a serious menace to the alfalfa grower. Comparatively little work has been done by scientific men in studying the dodders and methods of eradication, and the fact that the little rootlets or suckers (haustoria) become so firmly affixed to the host plant that it must be destroyed together with the parasite, has made the work hard and the results obtained unsatisfactory. There are a number of methods by which dodder may be spread through a field. As soon as it becomes thoroughly established on a host plant, the many little branches, waving about like the shoot produced from the seed, attach themselves to other plants, and thus the colony is increased in size. In legumes, the host plant first attacked soon dies, but before this occurs, the parasite has become firmly established on adjoining plants and is reaching out and completing the colony. As soon as a host dies, the dodder also perishes, but before this happens it is very likely to have blossomed and seeded. “In the operations of mowing, tedding, raking and drawing the alfalfa hay, these little colonies are spread about the fields by the machines and the workmen, and on the horses’ feet. The sale of infested hay is a prolific means of dissemination. Hunters and pleasure seekers, walking through the fields, notice the peculiar corn-silk-like growths and often, by picking up particles of it which are soon cast away, establish new colonies. The flower is very peculiar and attracts the attention of people passing, who are apt to pick them together with some of the maturing seed, and scatter these over the fields. In a pastured field, the animals spread the seed to some extent while moving from place to place in feeding. The most serious menace, however, is from the purchase of impure seed; farmers should always be absolutely certain that the alfalfa seed which they are buying is thoroughly recleaned and that no small weed seed is to be found in it. One should never sow clover or alfalfa from a field or even from a locality in which dodder is known to exist. It is probable that the seeds thoroughly ripened will retain their germinating powers for some years. The purchase of hay from dodder infested fields, or the purchase of manure from barns where infested hay has been fed, are sure sources of contamination.