. A text-book of mycology and plant pathology . Plant diseases; Fungi in agriculture; Plant diseases; Fungi. 548 SPECIAL PLANT PATHOLOGY killed presents a dark-brownish appearance. If the causative organ- ism, which is a small rod-shaped bacillus, is sprayed upon the sweet pea plant, the disease makes its ap- pearance from seven to ten days after artificial infection and the symptoms are similar to those pro- duced in nature. The bacillus is rarely found in chains and seldom united in twos or fours. Its flagella are not easily demonstrated, as they are shed so readily that not more than two to
. A text-book of mycology and plant pathology . Plant diseases; Fungi in agriculture; Plant diseases; Fungi. 548 SPECIAL PLANT PATHOLOGY killed presents a dark-brownish appearance. If the causative organ- ism, which is a small rod-shaped bacillus, is sprayed upon the sweet pea plant, the disease makes its ap- pearance from seven to ten days after artificial infection and the symptoms are similar to those pro- duced in nature. The bacillus is rarely found in chains and seldom united in twos or fours. Its flagella are not easily demonstrated, as they are shed so readily that not more than two to five may be stained and these are generally quite short. If properly fixed and stained, very long delicate flagella may be dem- onstrated, 8 to 12 in number, and peritrichous. Sweet Potato (Ipomcea batatas), Poir) Black-rot (Spheeronema fimbriata (Ell. & Hals.), Sacc).—We owe our past knowledge of this disease to Halsted, who in 1890 described this, as well, as other diseases of the sweet potato. It is a seed-bed disease, a field disease and a storage trouble. It is characterized by irregular hard, dark areas, or circular spots, varying in size from that of a dime to that of a silver dollar appearing on the skin of sweet potatoes (Fig. 195). If the root is injured, the fungus follows the line of injury. The sprouts are dwarfed and the foliage turns yel- low. The end of the hank is black- ened and charred and this is asso-. FiG. 195.—Sweet-potato black rot produced by a fungus, Sphar- onema fimbriatum. (After Harler, L. V. S. Farmers' Bull. 714. March 11, 1916.) ciated with a withering of the leaves which become black and Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harshberger, John W. (John William), 1869-1929. Philadelphia : P. Blakiston's Son & Co
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1917
