Apf. 15, 1921 
Bacterial Spot of Tomato 
155 
The causal organism is a monoflagellate bacterium which is described 
herein as Bacterium exitiosum , n. sp. It grows readily on a variety of 
culture media, producing yellow, translucent colonies. It produces 110 
acid or gas with carbohydrates and is highly sensitive to sunlight and 
very resistant to desiccation. In culture it will not tolerate a higher 
true acidity than P H 5. 
Foliage infection is stomatal and is readily obtained by atomizer inocu¬ 
lation. Fruit infection occurs only through puncture wounds. The 
invasion is intercellular at first. Inoculation of mature fruit is usually 
unsuccessful and is attributed to the fact that the hydrogen-ion concen¬ 
tration in mature fruit (P H 4.6 to 4) is higher than that tolerated in 
culture. However, green fruit and foliage yield P n values within the 
range of tolerance of the organism in culture. 
The organism overwinters on the surface of tomato seed and is thus 
disseminated. Commercial seed from fields known to be diseased has 
yielded about 1 per cent of diseased seedlings. The disease is also dis¬ 
seminated with diseased transplants. 
As a control measure disinfection of tomato seed in mercuric chlorid 
1 to 3,000 for 5 minutes, followed by thorough washing, is tentatively 
recommended as safe and effective. 
LITERATURE CITED 
(1) Clark, William Mansfield, and Lubs, Herbert A. 
1917. THR COLORIMETRIC DETERMINATION OF HYDROGEN ION CONCENTRATION 
AND ITS APPLICATIONS IN BACTERIOLOGY. In Jour. Bact. V. 2, no. I, p. 
1-34; no. 2, p. 109-136; no. 3, p. 191-236, 9 fig. References, p. 233-236. 
(2) Conn, H. J., et al. 
1918-19. methods of pure culture study. 
PRELIMINARY REPORT OF THE COMMITTEE ON THE CHART FOR IDEN¬ 
TIFICATION OF BACTERIAL SPECIES. In Jour. Bact., V. 3, no. 2, p. 
115-128. References, p. 126. 
PROGRESS REPORT FOR 1918 OF THE COMMITTEE ON THE DESCRIP¬ 
TIVE CHART OF THE SOCIETY OF AMERICAN BACTERIOLOGISTS. In 
Jour. Bact., v. 4, no. 2, p. 107-132, 1 fig. References, p. 131-132. 
(3) Coons, G. H. 
1918. MICHIGAN PLANT disease survey For 1917. 20th Rpt. Mich. Acad. Sci., 
p. 425-450, pi. 41-50. Literature cited, p. 448-449. 
(4) -and Nelson, Ray. 
1918. THE PLANT DISEASES OF IMPORTANCE IN THE TRANSPORTATION OF FRUITS 
and vegetables. Amer. Railway Perishable Freight Assoc. Circ. 
473 ~ a > 59 99 %• 
(5) Earle, F. S. 
1900. tomatoes. Ala. Agr. Exp. Sta. Bui. 108, 36 p., illus. 
(6) Groenewege, J. 
1912. DE ROTTING DER TOMATEN-VRUCHTEN, VEROORZAAKT DOOR PHYTOBACTER 
LYCOPERSICUM n. sp. In Meded. Rijks Hoogere Land-, Tuin- en Bosch- 
bouwschool [Wageningenj, deel 5, afl. 5, p. 217-239, 5 pi. 
