BUREAU OF PLANT INDUSTRY. 139 



eradication of citrus canker emphasis has been placed upon the 

 magnitude of the undertaking because of the extreme infectiousness 

 of the disease and the wide area throughout which it has been dis- 

 seminated. As has been pointed out in earlier discussions of this 

 work, no final statement regarding the complete eradication of the 

 disease can be expected within a period of at least two years. It 

 appears, however, that the campaign is progressing very satisfac- 

 torily in the commercially important orange and grapefruit regions 

 of Florida. Supplemental protective measures, such as formalin 

 treatments of infected soil and the protective spraying of groves ex- 

 posed to infection, are materially hastening the work of eradication 

 through the destruction of diseased trees and decreasing the number 

 of secondary outbreaks. Even in the few places where citrus canker 

 outbreaks have occurred in commercial districts and in old trees, it 

 appears possible to eradicate the disease promptly and effectively. 

 Although thorough inspection of citrus plantings will be necessary 

 throughout at least the coming fiscal year, it is believed that Florida 

 is now practically free from the disease. In Texas, Louisiana, Ala- 

 bama, and Mississippi the work has been somewhat more difficult 

 from the beginning, because of the more scattered character of the 

 plantings and the smaller interest in the matter due to the com- 

 paratively low commercial value of the citrus plantings as com- 

 pared with other agricultural developments of those States. Fur- 

 thermore, in all of these States the unusually severe tropical storms of 

 the present year have caused an unexpectedly wide distribution of 

 citrus canker in some areas, practically entire counties having been 

 infected. Even in these States, however, the progress of the work 

 appears to be encouraging, and if no further unusual drawbacks are 

 encountered the disease will be effectively checked. South Carolina, 

 Georgia, Alabama, and Mississippi should have but a very small 

 percentage of infected trees at the close of the present fiscal year. 

 The eradication of the disease from Louisiana and Texas will ap- 

 parently be more difficult and will almost certainly require a greater 

 length of time. Material reduction in the quantity of infection has 

 been effected in Louisiana, but in some areas the disease has been 

 so widespread that it is as yet problematical whether its occurrence 

 in adjacent territory can be prevented. In Texas the ornamental 

 plantings of citrus, especially in hedges, extend over such a wide 

 area that the difficulties both of inspection and of effective eradica- 

 tion are extreme. 



Potato diseases. — Experiments leading to a determination of the 

 factors necessary for the production of disease-free potatoes in west- 

 ern irrigated sections have shown that organisms capable of causing 

 diseases of potatoes are probably present in all desert lands, but that 

 land previously in cultivation with grains and alfalfa may, when 

 disease-free seed is planted, produce a crop comparatively free from 

 disease. In southern Idaho the experiments on the control of pow- 

 dery dry-rot in storage have been completed and show that the losses 

 can be prevented by careful harvesting to avoid mechanical injuries 

 and by keeping the storage cellar at a temperature between 35° and 

 40° F., with proper ventilation. When it is necessary to store 

 in poorly ventilated or improperly cooled houses, the disease may 

 be effectively checked by disinfection with corrosive sublimate or 



72412°--agr 1916 10 



