BUREAU OF PLANT INDUSTRY. 145 



Farmers' Bulletins was 28. Twenty-seven papers were contributed 

 to the Journal of Agricultural Research and were afterwards re- 

 printed in separate form. Two papers were contributed to the 

 Yearbook of the Department of Agriculture and these also were re- 

 printed in separate form for special distribution. The publications 

 of the bureau (not including Farmers' Bulletins) reprinted during 

 the year total 23. 



No attempt is made in this brief report to outline the full work 

 of the bureau. Certain of tlie more striking results of the investiga- 

 tional work, however, that have become evident during the year are 

 here summarized. 



PLANT PATHOLOGICAL INVESTIGATIONS. 



Citrus canker. — During the summer of 1914 a new disease of 

 citrus trees, called citrus canker, was reported to Washington, The 

 information secured on hasty trips through various infected regions 

 convinced this department that the citrus industry was facing an 

 emergency of unusual gravity, yet there were no funds under either 

 State or Federal control adequate to make any effective attempt to 

 check the spread of the citrus-canker disease. Considerable sums 

 were contributed by the growers themselves, and organizations were 

 effected for accomplishing the actual burning of all diseased trees, 

 which appeared to be the only metliod of disease control promising 

 any success. An appropriation of $35,000 carried in the general de- 

 ficiency bill became available January 25, 1915, and immediately co- 

 operative arrangements were entered into with Florida and soon 

 after with the remaining Gulf States on an approximately half- 

 and-half basis, the department carrying the salaries and expenses of 

 pathological inspectors, the expenses of men engaged in actual de- 

 struction of trees being borne by the respective States. The work 

 of inspection and eradication has progressed very satisfactorily, 

 although the seriousness of the disease and tlie number of localities 

 infested are much gi-eater than Avas at first supposed. Because of 

 the extreme ease of transmitting infection from tree to tree by con- 

 tact with animals or by insects, the disease has not yet been eradi- 

 cated. In Texas, Mississippi, and Alabama it appears that the 

 greater portion of the diseased areas have been determined and the 

 diseased trees destroyed. If it is possible for these States to main- 

 tain a thorough inspection during the coming year there is reason to 

 hope for the complete eradication of citrus canker from these 

 regions. 



In Florida the infected areas and the areas which are under sus- 

 picion appear to be safeguarded by the present system of inspection, 

 although the complete elimination of the disease from this State will 

 probably require expenditures of considerable magnitude for at least 

 two years more. 



Up to the present time it is estimated that the Gulf States have 

 expended approximately $50,000 in eradication work. The depart- 

 ment has spent approximately $33,000 for this purpose. 



The bureau has determined the cause of the citrus canker disease 

 to be a new species of bacteria, to which the name Pseudomonas citri 

 Hasse has been given. In the hope of developing new methods of 

 disease control, experimental work is being conducted by this bureau 



22814°— AGE 1915 10 



