304 BACTERIAL DISEASES OF PLANTS 



Little is known regarding the geographical distribution of 

 this disease. It was first received at the Laboratory of Plant 

 Pathology in Washington on cauliflower leaves from Southeast- 

 ern Virginia in April and May, 1909. Subsequently (1912) 

 something on cauliflower resembling it was received from Pal- 

 metto, Florida, and Miss McCulloch succeeded in isolating an 

 organism that culturally seemed right but no inoculations were 

 made. Later (1916) from cauliflower heads grown at Sanford, 

 Florida (Fig. 232), the organism was plated out (Fig. 233) and with 

 it pure culture inoculations were obtained (Fig. 234). In 1918 it 

 was received from Prof. H. H. Whetzel on cauliflower leaves 

 collected in Ithaca, New York (Fig. 235) . At first Prof. Whetzel 

 thought that the disease was only a peculiar form of the black 

 rot (see No. II) but since the leaves were without marginal 

 infection and the petioles were not diseased, and the spots did not 

 yield any yellow organism, he sent the leaves on to me to know 

 what it was. Aliss McCulloch obtained from it her Bacterium 

 maculicolum, with pure cultures of which she secured typical 

 infections on cauliflower in one of our houses, and from such 

 infections again obtained in pure culture typical colonies of the 

 organism (Fig. 236). In April, 1919 we received it from the New 

 Orleans market (courtesy of Lex R. Hessler) on cauliflowers said 

 to have been grown in California. 



This disease probably occurs also in Australia, that is, in 

 1900 I received specimens of cauliflower leaves and cabbage 

 leaves from Prof. D. McAlpine in Melbourne, bacterially spotted 

 with what I now believe to be this disease. His letter states 

 that it is the cause of serious damage. 



The conclusion respecting occurrence of the disease in cab- 

 bages depends upon artificial inoculations made in Washington 

 in 1909 and 1910. 



We owe our knowledge of this disease to the researches of 

 Lucia McCulloch, carried on in my laboratory during the years 

 1909, 1910, 1911 and later. No one else appears to have written 

 upon it. 



Cause. — The cauliflower leaf-spot is due to Bacterium maculi- 

 colum AlcCuUoch. This is a moderately growing, white, motile 

 (even after 4 months in beef bouillon at 0.5°C. to 1.5°C.), 1-5 



