« I.III HOOT OK < Hl'( IFEHS 



99 



root to W loss sovt-rc on niarsli .-iiul Iicatli soils. Soils 

 poor in liiiu- jifiit-rally favor dtvi-lopniciit of the dis- 

 ease, accordin'T to Kv(Ksli\ nu'r ('91). Masscc ("5I(>). 

 Laubcrt ('35a) Hiirkhardt ("15). Tricschniann 

 ("17). Hos ('18). Hronu-r ('23-28) Kindshoven 

 (•2n. Hall (10). and .\tkins ('22). Nauniov ('27) 

 found that soils with a lime (in terms of oxide) con- 

 tent of 0. 1 per eent or more are sienerally free of the 

 disease. Init Honig ('31 ) reported tiiat in the vicinity 

 of Munich soils with a 58 per eent linu- content were 

 heavily infested with clul) root. Herjiers ('2!») and 

 Honiir ohstrved tli.it the di.sease is very aliundant in 

 soils which heat up readily. 



The jihysical character of the soil also influences 

 the infective ability of the fungus spores according 

 to Fedotova ("28). In ordinary grey garden soil with 

 40.000 s|)ores |>er ec. of soil. 66 l)er cent of the ])lants 

 became infected, wliile in lilack. greenhouse dirt witli 

 100.000.000 s])ores per ce. only 12.5 per cent of the 

 plants were clubbed. N.uimov ('28) also found that 

 in clayey soils 20.000.000 spores per ce. of soil were 

 necessary for optimum infection, while in humus-rich 

 soils 100.000.000 were essential. He. furthermore, 

 reported that in the vicinity of Leningrad the spores 

 do not remain viable in the soil in the absence of hosts 

 for more than three years unless fairly high tempera- 

 tures and humidity are maintained. 



The observations of most of the workers men- 

 tioned above were not correlated with exact data on 

 the water-holding capacity and acidity of the respec- 

 tive tvpes of soil, and it is quite probable tliat the in- 

 creased infection and severity of club root reported 

 on clayey, heavy soils and those rich in humus are 

 due not so much to the pliysical nature of the soils 

 as to their high acidity and water-holding capacitv-. 



Hosts and Dcfjrcc of Infection 



Club root was first observed on cultivated cru- 

 cifers. but later it became evident that wild species 

 of the mustard family also are susceptible to this dis- 

 ease. Woronin reported hyi)ertrophied roots of 

 Ibi'ri.s- in 1878. and some years later Magmis ('93) 

 and Henning ('96) found other genera and species 

 attacked by /'. Brass'icao. Halsted ('92-'99) ap]jears 

 to be the first to have undertaken a more extensive 

 study of the host range, and since that time this 

 phase of the disease has been intensively investigated 

 in various ])arts of the world. Club root is confined to 

 species of the mustard family, and although reports 

 of its occurrence on plants outside of this family are 

 to be found in the literature, they have subsequently 

 been proven false. The number of hosts is large, and 

 in the following table are listed the cruciferous spe- 

 cies which have been examined for the presence of 

 club root. Included also is the degree of infection 

 found bv investigators who have studied the host 

 range of /'. liraxsictie. Previous authors have usu- 

 ally arranged the genera and species according to 

 sub-families, but for the sake of convenience they are 

 listed in alphabetical order below. 



Index to .\i-thohs Citko .vxd Deouee of 

 IxKEiTio.v or Hosts 



.\pi)cl = A)i|><-I iiiul Werth ('1(1) 



fun. = C'uniiiii;;li!ini {'II) 



Clint. = Clinton ClUi) 



Da. = Davis {'-■'>) 



Erick. = Erirksson ('9(i. ",'()) 



Gi. = Giblis (•;}-') 



Gl. = GleisluTf; (V3) 



F. S.= F. .S. (•-'()) 



Hal. = Halsted (•<).' 'OO) 



Ham. = Haininarlund ("l.")) 



Henn. ^ llinninp ('9()) 



Hon.= H()nif:C3I) 



Host. = Hiisterniann ('-1) 



,Tam. = Jamalainen {"Mi) 



Katt. = Katterfeld ('23) 



Mag. =: .Mapiuis ("93) 



Mass. ^Massee ("96) 



Mil. =^ Miiller-Tliurgau and (Jsterwalder ('23) 



N. N.^ Anonymous ('53) 



Naum. ^ Naumann ("13) 



N. = N'aumov (■14-' -'8) 



Rain.^ Rainio ("303) 



Ravn. = Ravn ('08) 



Roc. = Roclilin ('33) 



Ros.= Rostnip ("93) 



Schl. = Schleycr ("07) 



Sit. = Sitensky ("98) 



Ssach. = SsaciiarofF ('16) 



Svec. = Svec. ('-'3) 



Weiss. = Weiss ('18) 



Wor. ^Woronin ('78) 



= no infection 

 -f = weak infection 

 -|--|- = medium infection 

 -|--|--|- = severe infection 



Aethionema arahicum 

 A. hujcbaum'ii 

 A. cappad'icum 

 A. rotuudifolitim 

 AUiaria nffic'inaVis 

 Al i/xsinii al pest re var. 



odor at u m 

 .1. alpestre 

 A . ahjusoides 



A. argenteum 



A. hornmiilleri 



A. beiithami compactum 



A. eali/chium 



A. cam pest re 

 A. condensatum 

 ./. corymbosum 

 A. desertorum 

 A. edeiif Ilium 

 .1. lischerianiim 

 A. r/emonense 

 A. idaeinn 



A. marilimum := Lobii- 

 laria maritime 



X. ('21) 

 Katt. 



N. ('25) 



N. ('15) 15% 



Mil. 0; Ravn; Jam. 



N. ('13) 107f ; Roc. 17% 



Hal.; Ravn. 



Gl. 20%;N. ('12)+;N. 



('13)4-. Cun. 51.1%; 

 Jam. 

 GI. 0; Jam. 

 Jam. 10.5%-11.6% 

 GI. 71.13% ;N. ('12)+; 



N. (-13) + 

 Jam. 3.8% 

 Cun. 33.1% 

 Jam. 3l7ri 



N. ('25)0; Roe. 57% 

 N. ('15) 507o 

 Jam. 

 N. ('15) 5% 

 .lam. 1 l-.5% 



HaI.4-;Ravn. Cun. 11.2- 

 50%;X. ('15) 5%; 

 Jam. 



