threads must reach the growing tip of the host and develop with it; thus giving no sign of their presence until the plant is well grown and the heads are formed. But the growing point can only be reached when the very young seedling is attacked; therefore all attacks at a late period in the life of the host are soon overcome and outgrown. Now the tuft of hairs or "beard" and the "hulls" of the grain afford very convenient lodging places for smut spores, which are thus sown with the seed, germinate with it, and are ready to attack the young seedling at just the time when their attack is most effectual. Besides, these spores germinate most freely in fresh manure, and produce multitudes of germs which can attack the host plant under favorable circumstances. As it is probable that the spores can pass through the animal body unharmed, the manure from animals which have eaten smutted grain must be a very important source of infection. But it has been shown that the reproductive power of these germs becomes exhausted in the course of a year in manure; therefore old and well rotted manure, while otherwise better for the crop, is also harmless as a carrier of disease.

Professor Kellerman, formerly of the Kansas Agricultural College, has estimated that in Kansas the average annual loss of oats from this disease is equal to six or seven per cent. of the crop, and there is no reason to suppose that this estimate is too high for our own State. On the basis of the statistics of the United States Department of Agriculture this would give an annual loss in Massachusetts of $20,000 from this single smut. Nearly the whole of this amount might very easily be saved, if our farmers would apply the very simple treatment which will certainly limit the disease to an occasional stalk. This consists in soaking the seed for fifteen minutes in hot water, kept at a temperature of 1320 F., or for twenty-four hours in a solution of one pound of potassium sulphide (liver of sulphur) in twenty-four gallons of water. Neither of these treatments injures the seed, but, on the contrary, distinctly increases the crop.

Of the barley smuts (Fig. 2) one seems to yield readily to the same treatment, while the other seems not to be prevented by it; but, as both forms commonly occur on the

same field, at least a considerable decrease in the loss from smut may be expected to follow the treatment of barley with hot water before planting.

Wheat is not a crop of sufficient importance in Massachusetts to make any extended mention necessary here. It is subject not only to the loose smut mentioned above (Fig. 3), but also to the so-called hard or stinking smut or "Bunt" (Tilletia sp., Fig. 6). The latter of these is completely controlled by the hot-water treatment, but the former seems not to be affected by it.

A few practical directions for applying the hot-water treatment may be useful here. The seed should first be thoroughly wetted in cold water, and all imperfect seeds and other bodies which float on the top skimmed off. Two kettles of water should be provided, that in one at a temperature of 110° to 120°, and that in the other at the temperature required for the treatment, 132°. The latter should be kept as nearly as possible at the same temperature throughout the treatment, by the addition of hot or cold water whenever the thermometer shows it to be necessary. The seed is taken in lots of perhaps half a bushel at a time in a basket of wire gauze or a bag of very loosely woven material, and plunged first into the cooler water, lifted out and plunged again until it is thoroughly wetted and warmed. This is important, that the seed may not cool the hotter water too much. Now the basket or bag is transferred to the latter and allowed to remain fifteen minutes, during which it is occasionably lifted and lowered and turned about, to ensure the complete wetting of every grain. When the seed is removed it is quickly cooled with cold water and spread out until it is dry enough to be sown.

In the case of the corn smut it is not merely the young grains which are attacked, but the pustules may be found upon any part of the plant; and an infection of any part sufficiently young to be penetrated by the fungus gives rise in a few weeks to smut pustules. Thus the plant is not beyond liability to infection until all its tissues are hardened; that is, until the "tassel" appears.

The only treatment for this trouble which can be confidently recommended is the prompt removal and destruction

of all smutted parts as soon as they appear. It should hardly be necessary to call attention to the fact that to throw them into the compost heap is not to destroy them, but is often the surest means of perpetuating and disseminating the disease.

Fig. 5 shows a portion of a "tassel" of corn attacked by smut.

The leaf-smut of rye (Fig. 4) forms its black masses on the leaves and stems of rye, which are often considerably distorted by it. It does not, therefore, cause a direct loss of grain, but indirectly reduces the crop by weakening the plants which are attacked.

The same is true of the onion smut, which forms its pustules on both leaves and bulbs, and commonly kills its host. If the attack is not too severe, however, the plant may recover, though greatly weakened and never producing a strong bulb. It appears that only the young seedlings are susceptible to attack. This smut is propagated by means of the soil, and its spores may retain their vitality in the earth for several years. Treatment must consist in sowing with the onion seed some fungicidal substance which shall prevent the development of the smut spores in its vicinity, and the consequent infection of the seeding onions. The substance which gives most promise in this line at present is flowers of sulphur, although its protective effect is not all that can be desired. When a field becomes badly infected it should be used for some other crop, and the onion crop transferred to fresh ground for several years, at least.

For the assistance of any who may not feel certain as to the identify of the diseases here discussed, a plate is appended showing the characteristic appearance of the various smuts here mentioned, except that of onions. This plate was made from a photograph taken directly from specimens of diseased plants, and shows the effects of the various fungi on their respective host plants very clearly. With its help one should be able to identify the diseases represented without doubt.

EXPLANATION OF PLATE I.

Appearance of Some Smut Diseases.

(All figures of natural size.)

Fig. 1. Loose Smut of Oats, Ustilago Avena (Pers.) Jens.

Loose Smut of Barley, naked form, U. nuda (Jens.) Kell. & Sw.
Loose Smut of Wheat, U. Tritici (Pers.) Jens.

Fig. 2.

Fig. 3.

Fig. 4.

Leaf Smut of Rye, Urocystis occulta (Wallr.) Rabh.

Fig. 5.

Smut of Corn in the staminate flowers or "tassel," Ustilago maydis (DC.) Cda.

Fig. 6. Stinking Smut or "Bunt" of Wheat, Tilletia fœtens (B. & C.)

Trel.

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