1 66 Journal of Agricultural Research voi. xix,No.4 



COMPARISON WITH OTHER SIMILAR BACTERIAL DISEASES 



Seasons of excessive rainfall and of abnormal conditions in the oat 

 fields similar to those of 191 8 have been recorded for 1890 and 1907-8. 

 For the earlier record we are indebted to Galloway and Southworth, of 

 the United States Department of Agriculture (j), and for the later work 

 to Thomas F. Manns, of the Ohio Experiment Station (j). 



WORK OP GALLOWAY AND SOUTHWORTH 



In 1890 Galloway and Southworth (j) published a preliminary note 

 on what they termed "a new and destructive oat disease." This disease 

 appeared in May and June of that season and was so widespread and 

 severe as to threaten to destroy the entire oat crop of the eastern and 

 central States. The signs described were a browning of the tips of the 

 lower leaves, which spread until in a short time all the leaves were dead 

 and brown. Bacteria were found in these lesions. The account of the 

 disease by these authors, however, is too meager to afiford any basis for 

 judgment as to v.'hether or not it was the disease here described. 



During the seasons of 1906- 1909 blade-blight of oats was recorded again 

 over a fairly wide area, and in 1907 it was so severe in some fields as to 

 occasion a loss of from one-half to two-thirds of the crop. In 1908 the 

 blight was threatening at one time but eventually caused little loss. 

 The accounts of the disease from southern Canada and central and eastern 

 States are of the same general kind. They mention a general yellowing 

 of the lower leaves of young plants, the yellow color changing to a brown 

 or red under weather conditions unfavorable to the organism, such as a 

 sudden change from cool, cloudy weather to bright sunshine and higher 

 temperature. The fields are often described as having a rusted appear- 

 ance because of this reddening of the blades. The trouble was attributed 

 to various causes — to insects, to bacteria, to fungi, and to unfavorable 

 weather conditions. 



In 1908 Dr. Erwin F. Smith discovered this disease at Arlington Farm, 

 Va., photographed it, cut sections, and made cultures of the organ- 

 ism on various media, but did not publish upon it nor make any inocu- 

 lations, although it is quite certain from the type of the disease and the 

 nature of the cultures that he had the same organism here described. 

 This was perhaps its first isolation in pure culture. 



No other serious research work was undertaken until Thomas F. Manns 

 carried on his investigations during the seasons of 1908-9 at the Ohio 

 Experiment Station. 



WORK OF THOMAS F. MANNS, 1906-1909 



Manns (5) states that — 

 the disease manifests its presence by changes in color varying from a light yellowing, 

 which apparently checks but little the growlh of the oats, to a pronounced redden- 

 ing, which in severe cases kills the blades, leaving only the younger leaves and the 

 central axes alive. 



