Dec. io, 1913 
Foot-Rot of the Sweet Potato 
265 
40 days.—Medium studded with pycnidia. Exudate abundant. Pycnospores not 
typical, being immature in appearance and irregular in shape. 
67 days.—Hyphae hyaline. Many chlamydosporelike bodies. Long cylindrical 
bodies present. (PI. XXV, G .) 
Irish-Potato Cylinders (1036) 
4 days.—Dense, felty white growth covering all of potato cylinder. Medium slightly 
darkened. 
7 days.—Scattered dark (not black) pycnidia forming. 
9 days.—Pycnidia abundant, irregularly scattered; black, rather large. 
11 days.—Pycnidia black and conspicuous; uniformly scattered over the medium. 
14 days.—A slight exudate of spores from pycnidia. 
17 days.—Pycnidia crowded together. Slight discharge of spores. 
21 to 25 days.—Pycnidia numerous. No discharge of spores from the pycnidia. 
40 days.—Potato cylinder studded with pycnidia. No discharge of spores. Pycno¬ 
spores abnormal, being apparently immature and irregular in shape. 
67 days.—Hyphae hyaline. A few chlamydosporelike bodies. Long cylindrical 
bodies present. (PI. XXV, G.) 
Sweet-Potato Cylinders (1064) 
4 days.—White procumbent growth of fairly dense hyphae covering one-half of potato 
cylinder. Medium changed to a light chocolate-brown color. 
7 days.—Feltlike growth covering all of medium. Potato cylinders changed to a 
chocolate-brown color. Pycnidia forming; surface of medium grayish. 
9 days.—Pycnidia crowded together, forming a felty grayish surface on the medium. 
11 days.—Pycnidia formed in a dense grayish mass over surface of medium. Spores 
exuding from the pycnidia. 
14 to 25 days.—Slight discharge of spores. 
40 days.—Medium covered with pycnidia. Spores exuding abundantly from one 
tube, a little from another, and none from the remaining tubes. 
67 days.—Many long cylindrical bodies. Hyphae hyaline. 
Sweet-Potato Stems (1049) 
4 days.—A sparse spreading growth of white hyphae covering one-fourth of stem. 
7 days.—Sparse, grayish, somewhat irregular, cottony growth of erect hyphae. 
Pycnidia black, larger than on com meal, and resembling those on the vines 
under natural conditions. 
9 days.—Pycnidia black, uniformly distributed over medium. Spores exuding from 
the pycnidia. 
11 days.—Pycnidia numerous; pycnospores exuding from pycnidia in brownish 
globules. 
14 to 17 days.—Increase in the discharge of spores from the pycnidia. 
21 to 25 days.—Exudates from the pycnidia uniting. 
40 days.—Stems studded with pycnidia with long beaks. Discharge of spores from 
the pycnidia less than on com meal. 
67 days.—Hyphae somewhat brown. A few long cylindrical bodies 
Rice (967) 
4 days.—No visible growth. 
7 days.—Very slight mycelial growth. Many black, somewhat large pycnidia. 
9 days.—Mycelial growth sparse. Spores just beginning to ooze from the pycnidia. 
11 days.—Surface of medium studded with black pycnidia. Spores discharged from 
the pycnidia in small globules. 
