118 ''Sleepy Disease'' of the Tomato 



Reinke and Berthold(i7) have figured and described the fungus 

 V. albo-atrum as it occurs on the potato, and Carpenter (4) and Pethy- 

 bridge(U)) have more recently added certain details. The dominant spore 

 form is unicelhilar but a considerable number of monoseptate spores 

 are produced, especially in very old cultures, where indeed they may be 

 the dominant form ; and on certain media di- and tri-septate spores have 

 been found. 



The genus Diplocladium is distinguished from Verticillium only by 

 having monoseptate spores, but in spite of the fact that monoseptate 

 spores are produced in the present fungus, it is considered, that the many 

 points of similarity to V. albo-atrum, in particular the fact that Reinke 

 and Berthold originally described and figured monoseptate spores in 

 their work, and secondly, the inoculation results obtained, entitle the 

 Verticillium causing Sleepy Disease to be regarded as V. albo-atrum. 

 Upon certain agar media, chiefly those to which asparagin has been 

 added, slimy salmon-pink spore masses averaging 2 mm. by 1 mm. are 

 produced resembhng the pseudopionnotes of Fusarium cultures. The 

 septate mycelium is hyahne at first but in most strains becomes brownish 

 with age and varies from 2 /a to 4 /x in diameter. The mycehal cells, which 

 give rise to microsclerotia, become swollen and by a process akin to 

 budding a bead-like aggregate is formed, the cells of which thicken and 

 turn brown. Radiating from the microsclerotial masses are strands of 

 hyphae, unswollen, but thick-walled and brown. Strains which do not 

 produce microsclerotia usually give rise to a small amount of this brown 

 carbonised hyphae. 



2. Inoculation Experiments. 



Verticillium albo-atrum was isolated from wilted tomato plants in 

 1919 and tested for pathogenicity. Tomato plants, six weeks old, of the 

 "Comet" variety were inoculated in various ways with a pure culture 

 of the fungus. Six plants were used in each type of inoculation and six 

 were left as controls. The stem was first washed with water, then mercuric 

 chloride, alcohol and finally with sterile water. Small pieces of mycelium 

 from a pure culture were pricked in and the wound covered with tinfoil. 

 After inoculation all plants were placed in the tomato house. The controls 

 to all experiments described in this paper were treated in precisely the 

 same way as the inoculated plants except that no fungus was introduced. 



1. Stem Inoculations. 



(a) Hypocotyl. 27. iv. 19. Plants inoculated. 10. v. 19. Yollow blotches on leaf 

 immediately above point of inoculation. 14. v. 19. First leaf wilted; second leaf 



