1204 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



ing and rolling of leaves. Foliage leathery. Sometimes conspicuous phloem necrosis. 

 Generic name from Latin coriuvi, leather. 

 The type species is Corium solani Holmes. 



Key to the species of genus Corium. 

 I. Infecting potato. 



II. Infecting beet. 

 III. Infecting raspberry. 



1. Corium solani Holmes. (Handb. 

 Phytupath. Viruses, 1939, 120.) From 

 New Latin Solanum, generic name of 

 potato. 



Common name: Potato leaf -roll virus. 



Hosts: SOLAN AC EAESolanum tu- 

 berosum L., potato. Experimentally, 

 also other solanaceous species. Datura 

 stramonium L., Jimson weed; Lycopersi- 

 con esculentum Mill., tomato; Solanun) 

 dulcamara L., bittersweet; S. villosum. 



Insusceptible species : CHENOPODI- 

 ACEAE — Beta vulgaris L., beet. 



Geographical distribution: North 

 America, France, British Isles; probably 

 wherever potatoes are grown. 



Induced disease : In potato, leaves 

 thick, rigid, leather}^, and rolled, their 

 starch content excessive. Plants dwarfed. 

 Tubers few, small, crisp. Tubers of 

 some varieties show conspicuous phloem 

 necrosis, germinate with spindling 

 sprouts. 



Transmission: By aphid, Myzus persi- 

 cae (Sulz.) {APIilDIDAE), with incu- 

 bation period of 24 to 48 hours. Also by 

 Myzus convolvuli (Kalt.) (= M. pseudo- 

 solaniT\i(ioh.),M. circumflexus (Buckt.), 

 Macrosiphum solanifolii Ashm., and 

 Aphis abbreviata Patch (APHIDI- 

 DAE). By grafting. Not by inocula- 

 tion of expressed juice. 



Literature : Artschwager, Jour. Agr. 

 Res., 15, 1918, 559-570; 2i, 1923, 237-245; 

 Dykstra, ibid., 47, 1933, 17-32; Elze, 

 Phytopath., 21, 1931, 675-686; Folsom, 

 Maine Agr. Exp. Sta., Bull. 297, 1921, 



1. Corium solani. 



2. Corium betae. 



3. Corium rubi. 



4. Corium ruborurn. 



37-52 ; 410, 1942, 215-250 ; Murphy, Scient . 

 Proc. Roy. Dublin Soc, 17, 1923, 163- 

 184; Murphy and M'Kay, ibid., 19, 1929, 

 341-353 ; Schultz and Folsom, Jour. Agr. 

 Res., 21, 1921, 47-80; Smith, Ann. Appl. 

 Biol., 16, 1929, 209-229; /8, 1931, 141-157; 

 Stevenson et al.. Am. Potato Jour., 20, 

 1943, 1-in. 



2. Corium betae spec. nov. From Latin 

 beta, beet. 



Common names : Sugar-beet yellows 

 virus, beet-yellows virus, jaunisse virus, 

 vergelingsziekte virus. 



Hosts: CHENOPODI ACE AE— Beta 

 vulgaris L., beet; B. maritima L. ; B. 

 cicla; Atriplex hortensis L. ; A. sibirica 

 L. ; Clicnopodium album L., lamb's quar- 

 ters; Spinacia oleracea L., spinach. 

 AMARANTHACEAE —Amaranthus 

 retroflexus L. 



Insusceptible species: SOLAN A- 

 CEAE — Solanum tuberosum L., potato; 

 all other tested solanaceous species. 



Geographical distribution : Belgium, 

 Netherlands, Denmark, England; per- 

 haps Germany and the United States. 



Induced disease : In beet, young leaves 

 little affected; older leaves yellow, brit- 

 tle, short, thick, containing excessive 

 amounts of carbohydrates; necrosis in 

 secondary phloem. In spinach, yellow- 

 ing, necrosis between veins on old leaves. 



Transmission : Not by inoculation of 

 expressed juice. By aphids, Myzus per- 

 sicae (Sulz.), Aphis fabae Scop., Macro- 

 siphum solanifolii Ashm., and Ardacor- 



