534 Journal of Agricultural Research vol. xx, No. 7 



(2) A species of Fusarium can be readily isolated from the discolored 

 area, and infection of seedlings can be produced by inoculating the soil 

 with this fungus. The causal organism is shown by stained paraffin 

 sections to exist throughout the fibro-vascular system of infected parts. 



(3) The Fusarium concerned seems to be closely related to Fusarium 

 oxysporum (Schlecht.) Wr. but differs somewhat from this species in 

 morphology, physiology, and pathogenicity. 



(4) Infection has been secured with two strains of Fusarium oxysporum 

 from potato on tobacco but has not been secured with the tobacco strain 

 on potato. 



(5) The trinomial Fusarium oxysporum (Schlecht.) Wr. var. nicotianae, 

 n. var., is proposed for the tobacco-wilt organism. 



(6) The conditions favoring infection with the tobacco-wilt organism 

 are heavy soil infestation, wounded host tissue, a relatively high soil 

 temperature (28 to 31 ° C), and a susceptible variety. 



(7) It has been found that varieties of tobacco differ markedly in their 

 resistance to Fusarium-wilt. The White Burley variety is most sus- 

 ceptible, and the Havana Seed and Cuban varieties are among the most 

 resistant. 



(8) Where the disease threatens to become serious, growers are advised 

 not to grow tobacco on the infested soils and to avoid the danger of 

 infested seed beds. The most hopeful means of control appears to lie in 

 the development of strains resistant to the disease within the various 

 susceptible varieties. 



LITERATURE CITED 



(1) Bisby, G. R. 



1919. STUDIES ON PUSARIUM DISEASES OF POTATOES AND TRUCK CROPS IN 



Minnesota. Minn. Agr. Exp. Sta. Bui. 181, 58 p., illus. Bibliography, 

 p. 40-44- 



(2) Delacroix, Georges. 



1906. RECHERCHES SUR QUELQUES MALADIES DU TABAC EN FRANCE. In Ann. 



Inst. Nat. Agron., s. 2, t. 5, p. 141-232. Bibliographic, p. 203-205. 



(3) Johnson, James. 



1916. resistance in tobacco to the root-rot disease. In Phytopathology, 

 v. 6, no. 2, p. 167-181, 6 fig. 

 (4) 



1918. wilt disease of tobacco attributed to fusarium. (Abstract.) In 



Phytopathology, v. 8, no. 2, p. 76-77. 1918. 



(5) and Hartman, R. E. 



1919. the influence of soil environment on the rootrot of tobacco. In 



Jour. Agr. Research, v. 17, no. 2, p. 41-86, 8 pi. 



(6) Lounsbury, C. P. 



1906. tobacco wilt in kat river valley . . . In Agr. Jour. Cape of Good 

 Hope, v. 28, no. 6, p. 784-803, illus. 



(7) McKenney, R. E. B. 



1905. THE WILT DISEASE OF TOBACCO AND ITS CONTROL. In U. S. Dept. Agr. 



Bur. Plant Indus. Bui. 51, p. 5-8, illus. 



