CLl"!! HOOT OF inr< IKKRS 



98 



riiMpt.r VI 

 Diseases Caused by Species of Plasmodiophoraceae 



ALTHoriiii ALL known species of tliis family arc 

 parasitic only two members are economically ini))or- 

 tant as pathosrens of food crojis. As noted elscNvhcrc. 

 Plaxmodiophora linisxicac and Sponc/ospora siihtcr- 

 ranra cause diseases of crucifcrs and potatoes re- 

 s])ectivcly. which are eonimoidy known as eluh root 

 and powdery seal). The other species jjarasiti/.e 

 fungi, aljiae. cryijtojiams. ;ind wild or seldom culti- 

 vated higher plants. 



CLIH HOOT OF CRrCIFERS 



Club root is a destructive root disease of wild and 

 cultivated erueifers which is world-wide in distribu- 

 tion in temperate climates and known throughout the 

 world by a large number of common names. In Eng- 

 land. Scotland, and ^^'ales it is known as finger and 

 toe disease, anbury, hanbury. ambury. club root and 

 clubbing; in Russia as hernia or Kapoustnaja kila ; 

 Kro|)fkrankheit des Koliles. Kohlhernie. Klumpen- 

 fuss. Knotensucht. Fingerkrankheit. Kelch, Galle. 

 Knolle. Huas, Kuss, etc.. in Germany. Switzerland 

 and Austria ; Gros pied, maladic du Chou, and hernie 

 du Chou in France; Tubereulosi dei cavoli and Mai 

 de gozzo dei cavoli in Italy; Knoelvoet in Holland; 

 Kwab. Kwabbe. Kwabbeziekte. Knol. Knolziekte, 

 Kiinker. Knoo]). Knuist, Knobbcl and Kwabbel in 

 Belgium; Kaalbrok in Denmark: Klum))rots juka in 

 Sweden ; Dik Voet in South Africa ; club foot and 

 club root in U. S. A. ; and by various other names in 

 other countries. According to ^'anderyst ('04, p. 518) 

 the name Vingerziekte used by Woronin and numer- 

 ous subsequent writers for the disease in Belgium is 

 unknown in that country. 



From the economic standpoint club root is the most 

 important disease of cultivated erueifers. In badly 

 infested fields entire cro])s may be destroyed unless 

 stringent control measures are employed. In Ger- 

 many. England. Russia, the U. S. A., and other coun- 

 tries in Europe, Asia, and Africa .50 to 100 per cent 

 destruction of turnips, swedes, cabbages, etc., has 

 been rel)orted ( Brunchorst. '87; Rostrup, '93. '91; 

 Halsted. '93-'99; Eyeleshymer. '94; I.aubert, '0.5; 

 Reniy and Liistner. '11 ; (ieorgeson, '16; Gleisberg. 

 '20; Korff and Boning. '27. and others). \\'oronin 

 ('78) rejjorted that in 18()9 the loss in the vicinity 

 of St. Petersburg alone amounted to more than 

 $20,000,000. while Heri)ers ('25) estimated that the 

 annual loss in Ciermany runs into millions of marks. 

 In New York .State alone a loss of sever;d thousand 

 tons of cabbage were reported by Haskcl and Mar- 

 tin in 1918. Edson. Miller and Wood ("3.5, '3(>. 37) 

 have subsequently rei)orti(l losses of 5 to 100 per 

 cent in cruciferous ero])s throughout the U. S. A. 

 The most significant fact about club root is that it 

 spreads ra))idly, and once it lias become established 



in the soil, it uiakts the fields almost useless for 

 crueifer cultivation for a number of years. 



Tlie origin of club root is unknown, but its symp- 

 toms had been well described more than a century 

 before \\'oronin showed it to be due to a ))lasniodio- 

 ])lioraeeous organism. According to Biiliner ('22), 

 the disease is as ancient as its hosts. The occurrence 

 of spongy, fungus-like roots (radices fungosae) of 

 erueifers noted by Albert the (Jreat as early as tlie 

 i;ith century is supposed to relate to club root, and 

 his control practice of avoiding fresh stable manure 

 and the disposal of chaff appears to have been ac- 

 quired from the Roman Pallatius, according to 

 Bohiur. The disease was well known in Spain in the 

 l.)th century where cabbages were described as being 

 sy))hilitic (see \\'oroiiin. '78, p. .552), and the swell- 

 ings were thought to be due to the organism causing 

 syjihilis (Ruiz Diaz de Isla). The first report of its 

 occurrence in England was made by Ellis in 1736, 

 who believed the disease was contagious and due 

 probably to an excess of barnyard manure. Adam 

 discussed its wides])read occurrence in England in 

 1789. and it was subsequently reported in Scotland 

 from 1829 to 1831 by Farquharson. Abbay. and 

 Birne who thought it to be due to unsatisfactorv soil 

 conditions or unbalanced fertilizer practices. Abbay 

 saw the disease as early as 1801, and Anderson 

 stated tliat it first became troublesome in Scotland 

 about 1813. Renard rejiorted that it was first ob- 

 served on cauliflower in 1820 in France. By 1853 it 

 was fairly abundant around Hamburg. Wurzburg, 

 in the Rhine valley and other |)arts of Germany 

 (N. N. '53), and from 1855 on it appeared in vari- 

 ous parts of Norway (Jorstad, '30). Other workers, 

 including Curtis ('IS), Kiihn ('58), Henderson 

 ('67). Sorauer ('7^), Slingerhand ('94'), and others 

 (see Woronin '78, pp. 552-55 1) believed it to be 

 due wholly or in jiart to various insects and other ani- 

 mals. Buckman ('5i), however, claimed that club 

 root was due to reversion to the original wild forms. 

 By 1872 the disease had become so widespread and 

 destructive around St. Petersburg that the Royal 

 Russian Gardening Soeietv in St. Petersburg offered 

 a iirize for the solution of the cause and control of 

 hernia. \A'oronin began to study the disease inde- 

 ))endeiitly of this ofl'er in 1873. and two years later 

 he announced th;it it is caused by a |)lasniodiopIio- 

 raceous organism to which he subsequently ('78) 

 gave the name I'Jasmudiopliora Brassicae. 



Symptoms 



Club root disease is iisu.'illy characterized by 

 marked enlargement of the infected roots (PI. 2. fig. 

 1 ). and in exceptional eases tlie galls on cabbage may 

 reach the size of a man's fist and appear greasy-gray 

 and pale-yellow in color. In most cases the clubs are 



