164 



BACTERIA IN RELATION TO PLANT DISEASES. 



Judging from our experiments and from the way it has behaved in Michigan this new 

 disease bids fair to be a very serious one. Its geographical distribution is not known. In 

 191 2 it appeared on tomatoes in a hot-house at Arkport, in western New York.* The writer 

 is also inclined to believe it is identical with the potato disease described by Spieckermann 

 (see p. 1 66) as widely prevalent in his part of Germany (Westphalia), although the few 

 experiments I have thus far made upon potatoes have been negative. 



RESUME OF SALIENT CHARACTERS. 

 POSITIVE. 



A short, yellow, rod-shaped schizomycete, parasitic on solanaceous plants, especially 

 tomato (and potato ?), causing a slow, destructive disease of the whole plant. Isolated in 

 the United States by the writer from tomato stems (Michigan, 1909; New York, 1912). 

 Grows very slowly on +15 nutrient agar and +10 gelatin and also slowly in +15 

 nutrient bouillon. Liquefies gelatin slowly. Coagulates milk slowly, forming in test-tubes a 

 pellicle and a wide yellow bacterial rim. In tubes of litmus milk, inoculated copiously from 

 solid cultures (potato), no change in appearance until after the fourth day. On the ninth 

 day (temperature 26) there was a wide 

 yellow rim, a yellow pellicle, and the litmus 

 had changed to a gray blue. After 24 days 

 the litmus was wholly reduced, i. e., there 

 was not a trace of the 

 blue. The milk was thick, 

 yellowish, and opaque, 

 without much separation 

 of the whey from the 

 curd. There was a char- 

 acteristic wide yellow 

 bacterial rim, and in two 

 of the four tubes the milk 

 was distinctly stringy. 



On potato 27 days 

 old (temperature 26 C.) 

 there was a moderate 

 amount of yellow slime 

 both on the surface and 

 at the bottom of the Fig. 74. t Fig. 754 



water, but the fluid was 



not solid. Rather more growth than in case of Bad. stewarti, but not in quantity like Bad. 

 campestre. Potato moderately grayed. On slant agar 27 days old (temperature 26 C.) 

 beyond the streak were many scattered (discrete) small round colonies, pale yellow to deep 

 yellow. Blue peptone dextrose litmus agar is reddened and remains red after boiling. 



In fermentation tubes containing dextrose or levulose the originally alkaline fluids 

 were slightly acid after a month. Sensitive to sodium chloride. Quite sensitive to acids, 

 malic acid, citric acid, oxalic acid. Finally clouded +15 bouillons. It tolerates consider- 

 able alkali, i. e., it grows in 25 and 30 peptone bouillon. 



The organism was plated out and tested on tomatoes, and culturally in the Laboratory of Plant Pathology. 



fFlG. 74. Longitudinal section through a cavity in the inner phloem (o or b of fig. 72), showing bacteria wedging 

 apart the sieve-tubes and companion cells. Drawn free hand, and slightly diagrammatic, e. g., unchanged nuclei and 

 many of the pits in the sieve-plates omitted. No bacteria observed inside the sieve-tubes. Slide 539 F 7, middle 

 row, right section. Grand Rapids tomato disease. 



tPic. 75. Cross-section of inoculated tomato stem (first hot-house inoculations) showing the bacteria destroying 

 the undifferentiated cells in a nascent root. Grand Rapids tomato disease. Drawn with Zeiss 4 mm. obj. No. 2 eye- 

 piece. Slide No. 539 A 7 (or i), top row, section i from right. Stained with carbol-fuchsin. 



