DODDER SEED
Dodder seeds are somewhat smaller than alfalfa seeds ([pp. 45] and [47]), but are not separated from them except by careful recleaning; consequently, they are often sown along with the alfalfa seed, especially in that which has been imported. If a field is badly infested, it should be plowed up and devoted to some other crop for a few years. Prof. F. H. Hillman of Nevada (Bul. No. 47) says there are several kinds that infest alfalfa, but two kinds are especially common and destructive in this country. Cuscuta epithymum is the commoner. “The seeds of this ([p. 47]) are very small, and are almost sure to escape detection on casual examination of the samples; yet, once recognized under the lens, their presence may be easily discovered. They are so much smaller than alfalfa seeds that the use of a sieve of twenty meshes per inch separates them from the latter when only free dodder seeds are present. Not only are various other small weed seeds disposed of in the process, but little if any alfalfa seed worth buying is lost. The few ripened flowers of dodder retaining matured seeds, which sometimes pass the thresher uninjured, may be removed by proper fanning. It is safe to say that no purchaser of alfalfa seed can afford to neglect sifting his seed carefully with a twenty-mesh sieve, which is the mesh the writer recommends for the separation of this kind of dodder from alfalfa seed.
“Cuscuta arvensis is another dodder as destructive when once established. Its seeds ([p. 47]) seem to be less common, however. They are larger than the preceding, many of them being practically the same size as the smaller, more rounded alfalfa seeds, which they often strikingly resemble. Thus they are hard to detect, and cannot be removed without the loss of much small alfalfa seed. This should be the more dreaded of the two dodders, because alfalfa seed infested with seeds of Cuscuta epithymum can be made practically free from them with comparatively little loss and expense. Not so, however, with seed containing Cuscuta arvensis, which should not be purchased at any price. Dodder seeds can scarcely be regarded as an adulterant, yet as an impurity they are very common and most objectionable.” (See illustrations opp. [pp. 45], [46] and [47].)