1220 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



the end of the season, showing puckering 

 and downward curling of leaves at the top 

 of the plant, reduction in size of new 

 leaves, and shortened internodes, or they 

 may gradually become chlorotic and die. 



Transmission : By leafhopper, Eutettix 

 tenellus (Baker) (CICADELLIDAE) 

 with 4 to 12 hour preinfective period. 

 Through dodder, Cuscuta carnpestris 

 Yuncker (CONVOLVULACEAE). Not, 

 with any regularity at least, by mechani- 

 cal inoculation of expressed juice. Not 

 through seeds of diseased plants to seed- 

 lings germinating from them. The leaf- 

 hopper, Agalliana ensigera Oman {CI- 

 CADELLIDAE), is said to transmit a 

 South American strain of sugar-beet 

 curly-top virus, but evidence for identity 

 of the virus has not yet been reported in 

 detail. 



Thermal inactivation : At 75° to 80° C 

 in 10 minutes. 



Filterability : Passes Berkefeld V, N, 

 and W, Mandler medium and fine, and 

 Chamberland Li, Lg, Lo, Ly, L9, Ln and 

 Li3 filters. 



Other properties : Withstands alcohol 

 and acetone treatments. A pH of 2.9 

 or lower inactivates, but an alkaline reac- 

 tion as high as pH 9.1 does not inactivate, 

 in 2 hours. Virus active after at least 8 

 years in tissues of thoroughly dried young 



sugar-beet plants, 6 months in dried leaf- 

 hoppers, and 10 months in dried phloem 

 exudate. 



Strains : In general it has proved possi- 

 ble to modify strains by host passage, 

 some hosts like Chenopodium murale 

 L. appearing to select less virulent 

 strains, others like Stellaria media (L.) 

 Cyr. reversing this selection and restor- 

 ing virulence. 



Literature : Bennett, Jour. Agr. Res., 

 48, 1934, 665-701; 50, 1935, 211-241; 56, 

 1938, 31-52; Phytopath., 32, 1942, 826- 

 827; Carsner, Phytopath., 15, 1925,745- 

 757; U. S. Dept. Agr., Tech. Bull. 360, 

 1933; Jour. Agr. Res., 33, 1926, 345-348; 

 Dana, Phytopath., 28, 1938, 649-656; 

 Fawcett, Re vista Industrial y Agricola 

 de Tucumdn, 16, 1925, 39-46; Fife, Phyto- 

 path., 30, 1940, 433-437; Giddings, Phy- 

 topath., 27, 1937, 773-779 ; Jour. Agr. Res., 

 56, 1938, 883-894; Lackey, Jour. Agr. 

 Res., 55, 1937, 453-460; Lesley and 

 Wallace, Phytopath., 28, 1938, 548-553; 

 Murphy, ibid., 30, 1940, 779-784; Severin, 

 Hilgardia, 3, 1929, 595-636; Severin and 

 Freitag, ibid., 8, 1933, 1-48; Severin and 

 Henderson, Hilgardia, 3, 1928, 339-393; 

 Severin and Swezy, Phytopath., 18, 1928, 

 681-690; Shaw, U. S. Dept. Agr., Bull. 

 181, 1910. 



