298 BACTERIA IN RELATION TO PLANT DISEASES. 



In 1904 Paddock of Colorado, reported as follows : " The Hubbard squash is much sub- 

 ject to a bacterial blight, probably the same one studied by Dr. E. P. Smith. The growing 

 of this crop is always precarious on this account. The disease was more or less abundant 

 this season." 



In 1905, Dr. B. M. Duggar informed me that the cucumber wilt disease, due to B. 

 tracheiphilus, was extremely bad at Monroe City, Mo., and Palmyra, Mo., two nearby 

 places, in 1903 and in 1904. He saw the disease there himself in 1904. 



According to Kern (Indiana Plant Diseases, 1905, 1906) bacterial melon wilt prevails 

 chiefly in the Central and Southern Counties of Indiana, often causing a total loss. 



According to C. G. Woodbury, Associate Horticulturist, Purdue University Experiment 

 Station (letter to the writer under date of November 16, 1909): "The bacterial wilt (B. 

 tracheiphilus) causes an immense amount of damage every year to the cucumber and melon 

 crop of this State." 



In recent years many complaints have been received from Michigan, Illinois, Indiana, 

 New York, Connecticut, etc. Probably it would be entirely safe to estimate the loss from 

 this disease in the United States (where cantaloupes, cucumbers, pumpkins, and squashes 

 are often cultivated on a very large scale) at not less than $500,000 annually. At least one 

 pickle-factory in the West was abandoned on account of its prevalence. The writer has 

 not heard complaints from watermelon growers. The common wilt disease of that crop is 

 due to a soil-fungus (see Bull. 17, Div. Veg. Phys. and Path., U. S. Dept. of Agric., 1899). 



HISTORY. 



So far as known there is nothing definite in scientific or horticultural literature respect- 

 ing the occurrence of this disease prior to the beginning of the writer's experiments on it 

 in 1893 and since that date it has received, so far as known to the writer, no serious attention 

 from any other plant pathologist. 



In 1908, Troop and Woodbury endeavored to get some further light on the transmission 

 of this disease by soil or insects, but owing to defective screening (which permitted the 

 entrance of Diabrotica vittata) the experiment miscarried, but is not wholly devoid of 

 interest. Melon vines to the number of eighty were planted, two in a pot, in soil from a field 

 where all of the plants had died of the bacterial wilt in 1907. The pots were set together in 

 a field which had never borne plants subject to this disease. Half of them were screened, 

 half exposed freely. The soil in half of the pots of each lot was steamed previous to planting 

 (which would destroy any of the bacillus present in it). The wilt disease prevailed exten- 

 sively in each one of the four groups of plants most in the uncovered plants, and in those 

 on the steamed soil. In each case the ratio was about 2:1. Altogether, including the 

 replants attacked, there were 60 cases. 



So far as any conclusion can be drawn from these experiments it is confirmatory of the 

 writer's view first advanced in 1895 that this disease is distributed by Diabrotica vittata. 



