Mar. 4. 1918 Wilt Diseases of Okra 543 



test where but i and 6 per cent of wilt was secured. Verticillium albo- 

 airum stram 3156 inoculated through wounds of the hypocotyl gave 80 

 per cent of wilt in 14 days. 



The Verticillium- wilt of cotton, as observed in these tests can not be 

 distinguished from the very destructive Fusarium-wilt of this crop imless 

 a critical examination be made. It is possible that this wilt is present 

 in the cotton fields of the South and has been overlooked, owing to the 

 similarity of the two diseases. 



INOCULATION OF EGGPLANT 



Eggplant was found to be susceptable to the strains of V. alho-atrum 

 isolated from okra, eggplant (PI. 20), and snapdragon. Strain 171 7 

 from okra gave 85 per cent of wilt in 15 days; strain 1685 froni eggplant 

 gave 100 per cent in the same time, and strain 2985 from snapdragon 

 80 per cent correspondingly. The inoculations were made through 

 wounds of the hypocotyl on 45-day-old plants. 



INOCULATION OF BRABHAM COWPEAS 



Twenty-four-day-old seedlings of Brabham cowpeas were inoculated 

 through the hypocotyl with F. vasinjectum strain 3203 from okra. 

 Although held under observation for 60 days, no cases of wilt were 

 detected. 



CONCLUSIONS 



There are two similar wilt diseases of okra, caused, respectively, by 

 Fusarium vasinfectum and Verticillium alho-atrum. These diseases 

 can be differentiated only by isolating the causal fungi. The Fusarium- 

 wilt in general is more serious in the southern range of okra growing, 

 while the Verticillium-wilt is more serious in the northern range of this 

 crop. However, the former has been reported in Connecticut, and the 

 latter occurs in South Carolina and Alabama. 



The wilt diseases of the Irish potato offer a parallel case of two organ- 

 isms producing the same disease symptoms. Here, the Fusarium-wilt 

 is induced by F. oxysporum and the Verticillium-wilt by V. alho-atrum, 

 as in okra. Similarly, it is demonstrated in this paper for the first time 

 that cotton may have both wilt diseases. No doubt there are several 

 other economic plants, which act as host to vascular parasites of the 

 genera Fusarium and Verticillium — for example, China aster, ginseng, 

 eggplant, brambles. 



V. alho-atrum was isolated from the discolored vascular system of 

 wilting plants of okra, eggplant, potato, and species of Abutilon and 

 Xanthium, and was demonstrated in these studies to be the cause of a 

 wilt disease at least of okra, eggplant, and cotton. It was identified 

 from a wilt disease of snapdragon after its causal relation to this disease 

 had been established by Miss Nellie A. Brown, of the Bureau of Plant 



