1178 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



under identical circumstances. More 

 work is needed to show existing alliances. 

 Literature : Chamberlain, New Zealand 

 Jour. Agr., 53,1936, 321-330; New Zealand 

 Jour. Science and Technology, 21, 1939, 

 212A-223A; Clayton, Jour. Agr. Res., 40, 

 1930, 263-270; Gardner and Kendrick, 

 ibid., 22, 1921, 123-124 ; Hoggan and John- 

 son, Phytopath., 25, 1935, 640-644 ; Larson 

 and Walker, Jour. Agr. Res., 59, 1939, 

 367-392; 62, 1941, 475-491 ; Schultz, Jour. 

 Agr. Res., 22, 1921, 173-178; Smith, Ann. 

 Appl. Biol., 22, 1935, 239-242; Tompkins, 

 Jour. Agr. Res., 57, 1938, 589-602; 58, 

 1939, 63-77; Tompkins et al., ibid., 57, 

 1938, 929-943. 



15. Marmor betae H. {loc. cit., 72). 

 From Latin beta, beet. 



Common name : Sugar-beet mosaic 

 virus. 



Hosts : C HENOPODI ACE AE— Beta 

 vulgaris L., beet; Spinacia oleracea L., 

 spinach. 



Geographical distribution: France, 

 Denmark, Germany, Sweden, L^nited 

 States, England. 



Induced disease : In beet, discrete 

 yellowish secondary lesions or clearing of 

 veins on young leaves, followed by chlo- 

 rotic mottling of newly formed leaves. 

 Darkening of vascular tissue. Leaves 

 bend back near tips, which sometimes 

 die. Intracellular bodies formed. In 

 spinach, 6 to 21 days after infection, 

 chlorotic flecks on young leaves. Plant 

 stunted, outer leaves killed, dying from 

 their tips back. Center of plant survives 

 for a time, but finally dies. 



Transmission: By inoculation of ex- 

 pressed juice, in dilutions to 10~^ By 

 aphids, Myzus persicae (Sulz.), Aphis 

 rumicis Linn., and perhaps Macrosiphuni 

 solanifolii Ashm. (= M. gei Koch) 

 (APHIDIDAE). No seed transmis- 

 sion. 



Thermal inactivalion : At 55 to 60° C 

 in 10 minutes. 



Other properties : Inactivated bj^ 

 standing in expressed juice for 24 to 48 

 hours at about 70° F. 



Literature : Boning, Forsch. Geb. Pflan- 

 zenkr. u. Immun. Pflanzenreich, 3, 1927, 

 81-128; Cent. f. Bakt., II Abt., 71, 1927, 

 490-497; Gratia and Manil, Compt. rend. 

 Soc. Biol., Paris, 118, 1935, 379-381; 

 Hoggan, Phytopath., 23, 1933, 446-474; 

 Jones, Washington Agr. Exp. Sta. Bull. 

 250, 1931; Lind, Tidsskr. Planteavl, 22, 

 1915, 444-457; Robbins, Phytopath., 11, 

 1921, 349-365; Schmidt, Ber. Deutsch. 

 Bot.Ges., 45, 1927,598-601. 



16. Marmor lactucae H. {loc. cit., 84). 

 From Latin lactuca, lettuce. 



Common name : Lettuce-mosaic virus. 



Hosts: COM POS I TAE— Lactuca sa- 

 liva L., lettuce; Senecio vulgaris L., 

 groundsel. Experimentally, also COM- 

 POSITAE—Sonchus asper Hoffm., 

 prickly sow-thistle. LEGUMINOSAE 

 — Lathyrus odoratus L., sweet pea; Pisum 

 sativinn L., pea. 



Insusceptible species : COMPOSITAE 

 — Sonchus oleraceus L., S. arvensis L., 

 Taraxacum officinale Web., Carduus ar- 

 vensis Curt. CRIJCIFERAE—Bras- 

 sica oleracea L. CUCURBIT ACE AE— 

 Cucumis sativus L. SOLAN ACE AE — 

 Lycopersicon esculentum Mill., Nicotiana 

 tahacum L., N. glutinosa L., Datura 

 stramonium L. 



Geographical distribution : United 

 States, England, Germany, Bermuda. 



Induced disease: In lettuce varieties, 

 clearing of veins followed by systemic 

 chlorotic mottling, dwarfing and defective 

 hearting; sometimes by scorching of leaf 

 edges, vein necrosis or necrotic flecking 

 between veins. 



Transmission : By inoculation of ex- 

 pressed juice, in dilutions to 1:100 if 

 mixed with a little 0.5 per cent sodium 

 sulphite solution and a trace of powdered 

 carborundum. By aphids, Myzus persi- 

 cae (Sulz.) and Macrosiphum gei Koch 

 (APHIDIDAE). Through seeds from 

 diseased plants. It is believed that seed- 

 borne virus is the most important source 

 of primary inoculum in the spring. 



Thermal inactivation : At 55 to 60° C 

 in 10 minutes. 



