70 Journal of Agricultural Research voi. vi. No. a 



including mandarins, tangerines, and Satsumas, have also been found to 



be diseased. The disease has been observed, too, on several varieties 



of lemons {Citrus medico) and limes {Citrus limetia). Thus far Citrus 



canker in Alabama has not been found to attack kuraquats, the four 



species of which Swingle (17) ^ regards as belonging to the genus Fortu- 



nella. It has been observed, however, on the leaves and twigs of the 



kumquat in Louisiana. Swingle (18) reports its occurrence on this host 



in Japan. 



HISTORY OF THE DISEASE 



Citrus canker is not of American origin, but beyond doubt was intro- 

 duced into the Gulf States from Japan. This statement is supported by 

 the fact that it is known to occur in Japan and the Philippine Islands (18), 

 and, so far as can be learned, it appeared in the United States several 

 years ago simultaneously with the importation of Satsuma and trifoliate 

 stock into Texas in order to supply the large demand for trees for Citrus 

 plantings. Whether it is indigenous to Japan is not known, but it is 

 probably native of parts of eastern Asia. Since its introduction into 

 Texas it has been disseminated by the shipment of diseased trees to other 

 States and has further been introduced by shipments to these States 

 direct from the Orient, so that it now occurs in parts of Florida, Alabama, 

 Mississippi, Louisiana, and Texas. 



Citrus canker had probably been present in the United States for 

 five or six years before it was recognized as a new Citrus disease. Speci- 

 mens were first collected in September, 1912, but it was not until July of 

 the following year (i) that the Office of Nursery Inspection of Florida 

 realized that these specimens did not represent an unusual manifestation 

 of scab caused by Cladosporium citri. This mistake in diagnosis had 

 also been made by inspectors in other Gulf States and by officers of State 

 Experiment Stations and of the Federal Department of Agriculture, 

 Japanese authorities had also mistaken this disease, since specimens 

 received at the Florida Agricultural Experiment Station (2) from Japan 

 had been identified as scab. The disease was brought to the writer's 

 attention in February, 1914, and has been interruptedly studied by him 

 since that time.^ 



A number of publications upon Citrus canker, all preliminary in nature, 

 have appeared. These papers call attention to the presence of the 

 disease in the several States, briefly describe its appearance, and recom- 

 mend concerted cooperation in its eradication. The disease was first 

 regarded as of fungoid origin, and the first claim that bacteria are the 

 primary cause of the disease was made by Hasse (6). The present publi- 



1 Reference is made by ntunber to " Literature dted," pp. 98-99. 



2 The writer severed his connection with the Alabama Agricultural Experiment Station on January i, 

 1916. This study therefore is incomplete, time not having been afforded for verification of all portions of 

 the study, and certain probleras which have appeared in connection with the work have not been inves- 

 tigated. However, it was deemed advisable to record the results of the studies thus far conducted. 



