THE FUNGI WHICH CAUSE PLANT DISEASE 627 



apically variable in form, ovate to elongate, curved, 1 to 5-septate, 

 subhyaline, 15-90 x 4-6 n. 



In America this potato parasite was noted in Vermont in 1905 

 and study of herbarium material revealed two earlier collections. 

 In Germany it was known in 1854 and it has been seen in many 

 parts of Europe since, sometimes in epidemic form.'*^ 



Conidia are abundant on the spots on stalks emergmg from 

 the stomata. The superior and inferior hyphse differ considerably 

 in length and branching. Brown bead-Uke chlamydospores form 

 within the leaf. The mycelium is strictly intercellular. The fungus 



FiQ. 424. — C. nicoti- Fio. 425. — C. niootianse, spores germinating and 



anffi. After Jones. entering stomata. After Jones. 



was studied in artificial culture by Jones & Pomeroy^'* and inocu- 

 lations were made, diseased spots appearing about three weeks 

 after inoculation by spraying with suspensions of spores. 



C. oicotianse E. & E. 



Spots amphigenous, pale, becoming white, with a narrow and in- 

 conspicuous reddish border, 2-5 mm. in diameter, conidiophores 

 amphigenous, tufted, brown, septate, 2 or 3-times geniculate above, 

 simple or sparingly branched, septate, 75-100 x 4-5 jit; conidia 

 slender, slightly curved, multiseptate, 40-75 x 3-3.5 /t, hya- 

 line. 



On tobacco it causes leaf spots.^'* The sporiferous hyphas are 

 abundant near the center of the disease spots. 



C. raciborskii S. & Sy. on tobacco in Java and Australia,^^' is a 

 near relative of C. nicotianae. 



