. The first principles of agriculture [microform]. Agriculture; Agriculture. DISEASES OF CROPS. 107 ito ed but ds Ito the atmosphere, as shown in P^igure 20. The growth of these fungi in wheat, barley, etc., is so rapid and vigorous that they soon split the straw, after which the disease spreads so quickly that whole fields of grain are often destroyed in a lew days. Rain and sud- den changes of temperature, ac- companied by close, warm wea- ther, are specially favorable to the growth of rust fungi. Over-rich- ness of soil also,. Fig. 20.—Section through a pustule of rust, enlarged to 2CXD tim
. The first principles of agriculture [microform]. Agriculture; Agriculture. DISEASES OF CROPS. 107 ito ed but ds Ito the atmosphere, as shown in P^igure 20. The growth of these fungi in wheat, barley, etc., is so rapid and vigorous that they soon split the straw, after which the disease spreads so quickly that whole fields of grain are often destroyed in a lew days. Rain and sud- den changes of temperature, ac- companied by close, warm wea- ther, are specially favorable to the growth of rust fungi. Over-rich- ness of soil also,. Fig. 20.—Section through a pustule of rust, enlarged to 2CXD times its natural size, and showing the thread- like bodies and spores. caused by too liberal manuring, tends to produce in plants a soft, loose growth which exposes them to the disease; and late sown crops, especially on low-lying undrained land, are most subject to attack. 268. Remedies for Rust.—There is no remedy for rust; and when the attack is serious, the sooner the crop is cut the better. Every day it stands after a bad attack, only lessens its value. The best preventives of rust are thorough underdraining, early sowing, and the selection of seed from varieties which have proved themselves as nearly rust-proof as possible. 269. Smut.—This is another well-known disease which attacks whea^, barley, oats, and some other crops. It also is caused by parasitic fungi, the spores of which germinats, not in the atmosphere, but in the soil. There are, moreover, two varieties of this disease, commonly known as hardstnut (or bunt), and loose smut. Smut spores do not grow while they are dry, as when stored with seed wheat; but when carried with it into the damp soil, they soon germinate. In germination they send out extremely fine thread-like bodies, which penetrate the young plant in the soil. These threads grow in the plant, and with it, till they at last reach the forming seed, when they produce millions upon millions of black spores that take the place of tUe floury sub* tanc
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectagriculture, bookyear
