536 Journal of Agricultural Research voi. xii. no. 9 



Fusarium vasiofectum Atkinson. 



Sporodochia and perfect pionnotes present, in mass ocherous-salmon colored, the 

 conidia being of the Elegans type, 3- to 5 septate, sickle-shaped, constricted at the 

 apex and pedicillate at the base (PI. 17, L,M). Conidiophores verticillately branched. 

 Normal triseptate conidia present up to 100 per cent, 23.8 to 46.0 by 3.4 to 5.1 m- 

 Four-septate conidia up to 35 per cent, 34.0 to 44.0 by 3.4 to 5.0 m- Five-septate 

 conidia up to 5 per cent, 34.0 to 56.0 by 3.6 to 5.0 n. Microconidia may be present 

 in subnormal cultures up to 100 per cent, 4.0 to 14.0 by 2. o to 3.5 m- in size. Chlaray- 

 dospores (PI. 17, 1) ellipsoidal to round, terminal, intercalary and conidial; when 

 unicellular measvtring from 8 to 1 5 m- Blue-gray sclerotia on potato cylinders. Strong 

 lilac odor on rice and other starchy media. Vascular parasite, cause of a wilt disease 

 of Gossypium Jierbaceum, G. barbadense, and Abelmoschus esculentus. 



VERTICILLIUM ALBO-ATRUM 



Veriicillium albo-atrum Reinke and Berthold is classified by Engler 

 and Prantl in the section Eu-Verticillium of the genus Verticillium of 

 the Mucedinaceae-Hyalosporae-Verticillieae. The conidophores (PI. 17, 

 A-D) are verticillately branched, conidia which readily fall being formed 

 at the tips of all the branches. The distinction between the three sec- 

 tions of the genus — that is, Eu-Verticillium Sacc, Oncocladium Wallr., 

 and Gliocephalum Sacc. is not sharply drawn. In the latter the conidia 

 are held together by slime, while in Eu-Verticillium and Oncocladium 

 this is not the case. In the opinion of the writer, V. albo-atrum should 

 more appropriately be placed in the section Gliocephalum, for this is 

 where it naturally belongs, if its characters are determined on the sub- 

 stratum (PI. 17, B, D). If examined in water mounts, rarely more than 

 one conidium would be found on each sterigma tip (PI. 17, C), and the 

 fungus would erroneously be placed with the section Eu-Verticillium. 



DESCRIPTION OF THE FUNGUS 



The conidia are ellipsoidal (PI. 17, A), unicellular, 4.0 to ii.o by 1.7 

 to 4.2 n, abscissed singly from the tips of verticillate-branched conidio- 

 phores. They may or may not cling to the tips of the sterigma in rounded 

 masses. In the absence of sufficient moisture in the air, relatively dry, 

 rounded aggregates of spores accumulate ; but with more moisture present 

 spherical drops appear on the sterigma tips by virtue of the hygroscopic 

 slime in which the conidia are embedded (PI. 17, B). With additional 

 moisture the drops rupture, leaving one immature conidium clinging to 

 the sterigma. These masses measure from 3 /* to a size where the water 

 drop breaks. The verticillate branches of the conidiophores are i to 7 to 

 a whorl or virtel, more commonly 3 to 5, and these in turn may bear 

 secondary branches in virtels. The branches are from 13 to 38 ^ long, 

 disposed in virtels 30 to 38 fx apart along the conidiophore. Conidiophores 

 consisting of a terminal branch and two primary virtels, are about 100 

 to 120 M in length, while those bearing four primary virtels measure 250 

 to 300 fi. Conidiophores with 7 to 8 primary virtels are occasionally 



