2IO 



BACTERIA IN RELATION TO PLANT DISEASES. 



Nothing is known to the writer concerning its occurrence in the far East or in the south- 

 temperate zone except a statement to him in 1910 by I. B. Pole Evans that it occurs on 

 pumpkins in the Transvaal. 



Contrary to certain statements the disease occurs in hothouses as well as in the fields, 

 but it is more generally prevalent in open-air culture than under glass. It occurred naturally, 

 however, two different years in a hothouse near Washington and in 1899 the writer iden- 

 tified it from a hothouse at Morrison, Illinois, where it did considerable injury. The 

 organism was cultivated out of plants from both houses and the disease was reproduced by 

 inoculations from these cultures. 



It is perhaps worth while to discuss the occurrence of this disease in the United States 

 at greater length. This disease was first observed by the writer (in 1893) near Washington, 

 D. C. (plate 13), and has been observed in fields and gardens around Washington every 

 year since 1893 (fig. 50). 



Fig. 50.* 



I saw it at Chuckatuck in Nansemond Co., Virginia, in 1898. This is the farthest 

 south I have seen it. 



It was cultivated pure from the interior of cucumber-stems received from Bristow, 

 Prince William Co., Virginia, July 19, 1897. 



Nothing is known of its occurrence south of Virginia. It might be looked for farther 

 south in the mountains, but hardly on the flat lands of the far South owing to its low thermal 

 death point. It is northern rather than southern in its distribution. 



It occurs in Pennsylvania and throughout New Jersey and Delaware, at least in places. 

 In September 1901, I saw the disease in cucumbers at Woods Hole, Mass., and in October 

 1903, in muskmelons farther north on Buzzard's Bay. I received it from Connecticut 

 in 1905 (melons), and from Rhode Island in 191 1 (cucumbers). It probably occurs all 

 over New England. 



I saw it in a field of cucumbers on the western end of Long Island in July, 1902, at 

 least one-third of the vines being affected. Gnawings due to the striped beetle (Diabrotica) 

 were numerous and many of the wilted spots originated from the bitten places (see Etiology) . 



*FlG. 50. — Patch of diseased Hubbard squashes on place of David Fairchild, at Chevy Chase, Md. 

 by Bacillus lrachrif>!iiliis. Summer of 1907, Pliotographcd by Mr. Fairchild. 



Plants wilted 



