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By 1894 it had crossed to the west side of the Missouri river, and was spreading in Minnesota, Iowa and Nebraska. In 1895 the injuries which it caused extended from Michigan to Colorado, Idaho and California, but the greatest damage resulted in the Dakotas and Nebraska.
The Russian thistle is an annual with a dense, yet light growth of circular or hemispherical form. The average plant is 2 to 3 feet in diameter, weighs 2 to 3 pounds when matured and dry, and is estimated to bear 20,000 to 30,000 seeds. Single plants have been found 6 feet in diameter, weighing about 20 pounds when thoroughly dry, and estimated to bear 200,000 seeds. It is ideally fitted to be carried by the fall winds, which easily break off or pull out its slender roots. A severe frost kills the plant at any time, but it produces seeds abundantly as far north as the Canadian boundary.
In Russia no effectual method of exterminating the weed is known. It is continually growing worse, and as a consequence the cultivation of crops has been abandoned over large areas in some of the provinces near the Caspian sea. Laws for its eradication were passed in South Dakota in 1890, in Iowa in 1893, and in Kansas, North Dakota, Minnesota and Wisconsin in 1895. In 1892 and again in 1893, the department of agriculture sent an assistant botanist to the Dakotas to work out the whole life history of the plant, and the method of dealing with it was established chiefly on the basis of the knowledge thus obtained. It is claimed that if this had been done before 1885, a saving would have been effected for the wheat growers of the northwest "sufficient to pay the cost of maintaining the whole department of agriculture for many years to come."1 Wetter seasons, more intensive farming, the building of fences, and the planting of trees reduced the Russian thistle to the ranks of comparatively unimportant weeds in the Dakotas, but in Nebraska stringent measures were necessary. Farmers cooperated in the work, and the weed was "hunted almost as strenuously as game would be," so that for some years it has not been an important factor in wheat growing in Nebraska.
Darnel (Lolium temulentum L.) has its widest distribution in Europe. It also occurs in the wheat fields of California, where 1 Yearbook U. S. Dept. Agr., 1897, pp. 95-96.
it is mistaken for chess. It is an annual grass, and can be cleaned from seed wheat by the chess method.
Cockle (Agrostemma githago L.) is a member of the pink family and a widely distributed weed of the wheat fields since ancient times. In size and weight its seeds resemble wheat grains so closely as to be removed with difficulty. They are easily seen in the grain, however, and are injurious to flour, consequently they render wheat less marketable. As cockle is usually not abundant, grows over a foot high, and is conspicuous because of its large pink blossoms, it can easily be pulled from the growing wheat. The seeds have great vitality and will germinate even if they have lain in the ground several years.
Wild Garlic (Allium vineale L.) is most troublesome to wheat in eastern United States. It grows about two feet in height. The flour is spoiled when the bulblets of the plant are ground with the wheat. These can be removed by careful screening. Badly infested land should be put into cultivated crops for a few years.
Wheat-Thief (Lithospermum arvense L.).—Other names by which wheat-thief is known are bastard alkanet, corn gromwell, redroot and pigeonweed. Its greatest damage is to meadows following wheat in rotation. Cultivated crops are the best remedy.
Wild Mustard or Charlock (Brassica sinapistrum L.) is so uniformly found in spring wheat that flouring mills make a byproduct of its seed. When not very abundant it is easily pulled in the field, for it grows nearly as high as the grain and has conspicuous yellow flowers. In small wheat fields where it is very abundant it can be killed by spraying the field with a 3 per cent solution of copper sulphate, using about 50 gallons of solution to the acre. It is claimed that the wheat is not injured.1 If wild mustard seed is covered with at least five inches of soil it will not grow, but thus buried it will' retain good germinating power for over 56 months. It comes up most abundantly through one inch of soil.
Thistles are of two varieties: Canada thistle (Cnicus arvensis), and common or sow thistle (C. lanceolatus). The latter is also known as spear, bur, and bull-thistle. It grows 2 to 4 feet high and has the better hold on the land where both 1 Cornell Bui. 216 (1904), p. 107.
infest the same area. The Canada thistle is a native of Europe and Asia. In Great Britain it is called corn or creeping thistle. Its growth is rather slender, and from one to two feet in height. Its deep-laid, extensively-creeping and sprouting rootstock make it one of the very worst of weeds. Both of these plants are constantly invading new territory, especially such as is continually cropped in wheat. The areas infested become useless for growing small grain. Intensive cultivation with a certain amount of hand work is the best remedy.
General Remedies.—While experiments in killing certain weeds by spraying with chemical solutions have been made, the most practical method is to prevent as far as possible the spread of their seeds. This is accomplished by sowing clean seed wheat, and by killing the weeds when they do succeed in starting. Conditions most favorable to the growth of wheat place the weeds at the greatest disadvantage. Intensive farming always finds effectual methods of dealing with them.
Losses.—The wheat growers lose millions of dollars annually on account of weeds. They are the largest factor in elevator dockage. In North Dakota1 47 samples of wheat were found to have an average real dockage of .64 pounds per bushel. This varies each year, and the average dockage for the 1906 crop of wheat was about 2 pounds in the Minneapolis market. If 500,000,000 bushels of wheat are grown in the United States annually, and the dockage averages only half of one pound per bushel, then over 4,000,000 bushels are not only waste, but they also injure the commercial value of the real wheat. Where large quantities of wheat are cleaned, the cost is about onefourth of a cent per bushel.
Birds.—In the United States 29 species and subspecies represent the family Icteridffi, a group of birds including those commonly known as bobolinks, meadowlarks, orioles, blackbirds, grackles and cowbirds. Rating the blackbirds in the order of their grain-eating propensities revealed by stomach examinations, and putting first those that eat least, the list reads: Bobolink, redwing, cowbird, rusty blackbird, yellowhead, crow blackbird, boat-tailed grackle, Brewer's blackbird and California redwing. Since the first two are the ones most complained of, the amount of grain actually eaten would not seem to be the 1 N. D. An. Report (1904), p. 45.
only factor to be considered in determining the relative harmfulness of the species. The dove, the sparrow and the crow also eat grain from the fields, as do many other species. None of these birds are, however, entirely harmful; indeed the good that many of them do by destroying injurious insects and seeds more than counterbalances the damage occasioned by the eating of grain. At least 50 different birds act as weed destroyers and help to eradicate nearly 100 species of noxious plants. The number of weed seeds eaten is enormous, one bird eating a thousand seeds of some kinds for a single breakfast. The insects eaten by these birds are also generally noxious. There is usually an equilibrium of organisms in nature, and birds become harmful only when they disturb this proper balance by increasing out of proportion to their environment.
"Yellow Berry."—This occurs in hard winter wheat. Some of the wheat berries are often lighter in color and weight than the hard red ones, and also have a lower gluten content. Overripeness and failure to stack the sheaves have been given as causes, but opinions seem to differ as to this. It is claimed that the annual loss in Nebraska is from one-half to one million dollars.1
"Glume Spot."—This fungus receives its name from the dark spots that it causes upon the glumes of wheat. It has been studied but little, and no remedy is known.
Wheat Scab (Fusarium culmorum) also attacks the glumes and causes lead-brown-colored sections in the spike, or even destroys the spike entirely. The loss is usually light, but may reach a maximum of about 15 per cent. The only remedy suggested is the burning of the stubble.
Smut.—Two kinds of smut attack wheat, stinking smut, or bunt (Tilletia tritici (Bjerk.) Wint.), and loose smut (Ustilago tritici (Pers.) Jens.). The enormous damage resulting from this disease attracted attention in ancient Greece and Rome. Hartlib called attention to the fact that smutty seed produces smutty grain, and he was perhaps first to record a remedy (1655). His three remedies for smut in wheat were liming the 1 Neb. Bui. 89 (1905), p. 50.