26o 
Journal of Agricultural Research 
Vol. XXI, No. 4 
The Ricinus organism was also inoculated successfully into the common 
nasturtium ( Tropaeolum majus T.)> another plant subject to Bacterium 
solanacearum. 1 
Subsequently it occurred to the senior writer to try out the organism 
on cotton, vanilla, and sunflower—three plants hitherto untried. 
Cotton plants when of any size proved resistant, but the young seed¬ 
lings are subject to the disease. Thus, if inoculations are made by 
needle pricks into the hypocotyl soon after the plants appear above 
ground they are first profoundly dwarfed (PI. 63) and then wilted and 
shriveled (PI. 64). Bacteria were then found in enormous numbers, at 
least in the parts above ground, the needle pricks being made near the 
cotyledons. These results were obtained in 1918, and the same results 
were obtained again in 1920, using Bacterium solanacearum plated from 
wilting .North Carolina tobacco (the Granville tobacco wilt). 
The common vanilla ( Vanilla planijolia Andrews) also contracted the 
disease. Under our hothouse conditions it was possible to produce wilt 
and brownrot only of the softer growing tips of the shoots (PI. 65), but 
the bacteria were traced a considerable distance farther in the vascular 
system, and it seems likely that under tropical conditions whole plants 
might be subject to the disease. A few plants only having been inocu¬ 
lated in 1918 (always by delicate needle pricks), the inoculations were 
repeated in 1920 with the same results, using Bacterium solanacearum 
obtained from North Carolina tobacco. These results were wilting and 
rot of the terminal shoots in about a week or 10 days’ time, brown to 
black stain in the tissues, with multiplication of the bacteria in the ves¬ 
sels (and in the parenchyma of the softer parts); and from the interior 
of one of these stems a pure culture of the right organism was reisolated. 
Sunflowers ( Helianthus annuus L.) inoculated in the soft stems when 
about one-fourth grown proved very susceptible. The culture used for 
this purpose was a subculture from a poured-plate colony isolated from 
diseased vanilla which was infected from a poured-plate single colony 
subculture from a diseased tomato which had been inoculated in the 
same way from a diseased Ricinus. The plants wilted in a week or two 
with the usual brown staining of the vascular system, and enormous 
numbers of the bacteria developed in the vascular system to long dis¬ 
tances from the point of inoculation, which was near the top of the 
plant, so that when cross sections of such stems were made the bacteria 
oozed out copiously (PI. 59, B), as a gray white slime even down to the 
surface of the ground. Here also there was a profound dwarfing. The 
Ricinus organism was reisolated from an inoculated diseased sunflower 
on Petri dish agar poured plates, and with a subculture from one of the 
colonies tomatoes were again successfully inoculated (PI. 66). 
1 Bryan, Mary K. a nasturtium wn/r caused by bacterium souan ace arum. In Jour. Agr 
Research, v. 4, no. 5, p. 451. 1915. 
