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 FUNGOUS ENEMIES "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. Bul. 89 (1905), p. 50. field, liming the seed, and soaking the seed over night in common salt lye. Though the efficacy of the remedies was doubted, there must have been some beneficial results, for it is claimed that the seed was invariably steeped. By the middle of the nineteenth century there were many methods of steeping, liming and brining wheat to prevent smut. It was found that the use of a solution of arsenic gave a clean crop from smutty seed. Just how fully the nature of smut was understood by these early writers does not seem to be clear, but they must have had considerable knowledge of the disease in order to pursue such correct principles in endeavoring to effect a cure. The black dust frequently filling the kernels of ripening wheat consists of thousands of germs of the parasitic smut fungus. These germs, or spores, have a great capacity for spreading over the fields, but the only real danger seems to be from those spores which lodge on healthy kernels, generally in the hairy ends. Chances are slight of clean seed being infected by being sown on ground containing smut spores. Spores have the same function as seeds of higher plants, and, the infected kernels of wheat being sown, the spores germinate at the same time as the wheat. The slender filaments penetrate the tissues of the wheat plant before the first leaf is put forth. From this point its growth is within the wheat plant, both plants growing together. It seems to be still undecided how these threads proceed below the upper two joints of the mature wheat plant, whether they pass upward through the pithy region of the stalks, or whether they follow the surface tissues, but it is probable that the method of smut growth is uniform throughout the entire plant. The fungus seems to die as it passes upward, and leaves few traces of its path. In the mature wheat plant smut seems to be found only in the chlorophyl bearing parenchymatic tissues. Nearly 30 rows of breathing pores in the skin covering of the straw run lengthwise with the stalk. Under these rows of pores are layers of succulent cells which produce the food eventually used in forming the wheat grains. The smut filaments remain close to the open pores, absorbing and taking the place of this cellular structure with its chlorophyl and protoplasm. No other cellular tissues are disturbed, and until the heads develop the presence of the smut can scarcely be detected without the aid of a microscope. A mass of smut threads then absorbs all the nourishment, fills the flower or grain, and soon converts it into a mass of spores. As the parasite lives at the expense of its host, the latter is weakened and stunted in proportion to the amount of smut. This may be great enough to dwarf the plants so as to prevent the formation of heads, or even to cause the stalks to die back to the ground, or it may be so little that the heads are never reached, simply the straw being infected. Much of the straw may be thus infected, greatly reducing the yield, even though apparently uninjured heads are formed. Smut filaments have also been found in grains which had formed starch. In general, smut and wheat seem to de d a SECTIONS OF SMUTTED WHEAT STRAW At the left is a longitudinal section of a wheat straw and at the right a cross section. a, epidermal cells; b, smut filaments; c, fibrous cells; d, internal tissues. mand about the same meteorological conditions for their best growth. Smut will successfully pass the winter, even upon the open ground in North Dakota. Germs two years old have not lost their power of producing smut in a crop." Grains of wheat affected by stinking smut are slightly larger and more irregular than healthy ones. Such kernels, the socalled "smut-balls," are easily broken open, and the darkbrown powder with which they are filled has a very disagreeable and penetrating odor that pervades the whole bin of wheat, even if only a small per cent of the kernels are smutted. On this account they differ from all other grain smuts in that their presence can be easily recognized. Sometimes 1 Bolley, Proc. Tri-State Grain Growers' Ass'n., 1900. p. 86. 50 to 75 per cent of the heads in a field are smutted, and the remainder of the grain is so contaminated by the fetid spores as to be of very little value as flour and worse than useless for seed. Unchecked, these smuts increase from year to year, and they occur more or less abundantly in all wheat raising countries. Loose Smut of Wheat differs from the stinking smut in these respects: At germination its spores develop a chain of cells instead of an undivided tube; it has no fetid odor; it attacks both kernel and chaff; and it ripens when the healthy wheat is in flour. By harvest time the spores have all taken wings upon the wind, leaving a naked stalk in place of the head. It is known to occur in Europe, North America, northern Africa, central Asia and the West Indies. There are many localities in the United States where it is rare or entirely absent. A loss of 10 per cent or more of the crop is often occasioned by loose smut, and even as high as 50 per cent, but usually it is not as destructive as the stinking smuts. It seems to be more difficult to prevent, however, so that when once introduced into a field, it is more apt to STINKING SMUT remain. Remedies. Any means that destroy the vitality of the smut spores adhering to seed wheat but leave the latter unimpaired in its power of germinating are a safe preventive of smutted wheat. There are several ways of accomplishing this easily and perfectly with the stinking smut. In all treatments by immersion in solution, the seed should first be stirred in water in order to skim off the smut balls. Slaked lime will hasten drying, but is not essential. If the seed is LOOSE sown without drying, the drill must be set accordingly. SMUT |