iLlll HOOT OF (Hit IFKIIS 



115 



tioii. it is sjiid to lead to a more richly liraiu-lu'd and 

 (ilaiiuntous root systciii on tin- host (Apptl and 

 Si-lilunilicrgcr, '13. ' 1 I- : MiilK-r and Osfirwaldcr, 

 '■_';!). It is jifiicrally applii-d 10 cms. deep on infested 

 soil (Nauniann. '13 ; ."^chllnnl>erger. 1 I- ; 1 liltner .ind 

 KortV. 'Ki: l'oj)p. '1!»; and Hosterni.-nin and Noak. 

 '23). or at the rate of 1.000 cu. in. per hectare. Nau- 

 mann (12. '13), Schlumbcrger (1 0- Hiltner and 

 Kortf ('16), Ncger ('17), Popp, Schmid ('19), 

 .^eliatfnit .-md I.ustner ('20). Hiisterniann and Xoak 

 ^'23). and others have rel)ortid iuiieficial ert'eets 

 from the use of this prej)ar;ition. .\))l)el and .Schlum- 

 bcrger ('13. '\i). however, found it to he unsatisfac- 

 tory, and claimed that its ett'ectivcness is dependent 

 to a large degree on the weatlier. While .Steiner's 

 remedy has proven to be fairly cflfective in control- 

 ling club root, the detailed and bothersome method of 

 preparing and ai)])lying it as well as the high cost of 

 materials and transportation have not made it po))u- 

 lar and connncreially profit.-ible. 



.\s to the most suitable time and method of ap])ly- 

 ing lime for club root control various i)ractiees and 

 recommendations are to be found in the literature. 

 Eydeshymer ('91), Halsted ('96. '97), Laubert 

 ('0.5). Schlumberger ('!!■), Chupp ('25) and Ko- 

 blischek ('29) advocated application 3 to 6 months 

 before planting, wliile Erickson ('26) recommended 

 6 to IS months. Ciibbs ('32) found that if ])lanting 

 took ])lace too soon (less than 3 months) after lim- 

 ing, club root occurred 2^ .j-i inches below tlie sur- 

 face, while in fields planted 12 months after liming 

 infections were present only at 9—1 1 Yo inches. Gibbs 

 accordingly advised at least 3 and up to 12 months 

 between ])lanting and liming. As to the method of 

 application. .Sommerville ('94). Seltens])erger ('96), 

 Roger ('12). Koblischek ('29), and others recom- 

 mended drilling lime in with the seed or apjilying it 

 directly to the plant holes at the time of trans])lant- 

 ing. According to Ravn ('12, '13) it is immaterial 

 whether the lime is hoed in or plowed under. Since 

 infection appeared to be [jrevented to the depth to 

 which lime penetrates. Cunningham (1 l) advocated 

 mixing the lime down to 6 to 9 inches in the soil. 

 Miiller and Osterwalder ('23) also advised a thor- 

 ougli mixing of lime and soil. 



The manner in which lime o])erates against club 

 root is not very well understood. .Most workers have 

 believed that it prevents spore germination by rais- 

 ing the H-ion concentration of the soil, since the 

 spores germinate more readily in acid media, accord- 

 ing to inimerous investigators. Likewise, it has been 

 reported that infection rarely occurs above pH 7.2 to 

 7.1- ( Chup|). '28). That an increase in ))H is not the 

 sole determinating factor is indicated by the re])ort 

 of Honig ('31) that spores will germinate equally 

 well in alkaline media, and by the fact that club root 

 may occur in a high ))H environment. Whether or not 

 lime has a direct toxic and lethal effect on the resting 

 spores is uncertain. Bremer ('2:}) refuted this idea, 

 but later Whitehead ('36) claimed that lime is toxic. 

 Naumov ('27) found that calcium hydrate has no im- 

 munizing effect on cabbage, and concluded that its 



ecuitroUing efieet is due to direct .action on the ])ara- 

 site itself. .Seedlings which had been grown for two 

 months in sterile soil with ;i very higli lime content 

 were as susceptible .as the controls when tr.insferred 

 to infested soil. Naumov .also found tli.-it s.ilts of 

 other metals, p.articularly b.irium and magnesium, 

 have a controlling etVcct. and from these exi)eriments 

 he concluded that the deciding factor in the inhibi- 

 tory action of the salts on the parasite is not so much 

 on the nature of the metallic ion as the presence of 

 free hvdroxyl ions in the soil. In the case of calcium 

 cvan.'imide. Walker and I.arsen ('St) stated th.it its 

 toxicity is not due only to the basic substances 

 formed from it but also to the CHo anions in the soil 

 before hydrolysis is comi)letc. 



Basic Fertilizers 



While the nature of the inhibitory effect of lime is 

 not clearly known, it is nonetheless obvious from 

 experimental work that lime makes the soil environ- 

 ment unfavorable for club root infection and develop- 

 ment. Any fertilizer, therefore, which neutralizes 

 this effect is to be avoided. The selection of a fertil- 

 izer to be added to the soil previously or sown with 

 the seed determines to a great extent whether or not 

 liming will be effective. Acid fertilizers in general 

 and J)articularly superphosphates, basic su])erphos- 

 jjhates. superphosphates and carbonate of lime, 

 turnip manures, etc.. have been found to nullify the 

 effects of lime and stimulate club root. The substitu- 

 tion of basic fertilizers and their use with lime is ac- 

 cordingly essential and has been widely advocated 

 and l)racticed. A review of the literature shows, how- 

 ever, that the results have not always been strikingly 

 beneficial or commercially satisfactory. In t.ible i 

 are listed the most commonly used of these fertilizers 

 and their effect on club root. 



In addition to the fertilizers listed in table 1 oth- 

 ers have been used with varying success. Calcimn and 

 potassium nitrate give favorable results, according 

 to Brezhnev ('31'). Kindshoven ('21', '28) likewise 

 secured good results from calcium nitrate when used 

 at the rate of 50 gms. per sq. m. of soil. Sodium ni- 

 trate is effective when used in combination with lime, 

 according to Murphy ('27). 



Animnnium sulfate is ineffective as a fertilizer in 

 combating club root, according to \\'hitchead ('25) 

 and Osterwalder ('29). 



Mar/nesium carbonate reduces infection in well- 

 w.itered soil when used in sufficient amounts to raise 

 the ])H to 7.0 and usually inhibits the disease at pH 

 7.2 or above ( Larsen and Walker. '31). 



(ii/psum stimulates the development of club root, 

 according to I.indfors ('2 J), and in the o|)inion of 

 \\'ellman ('30) is comi)letcly ineffective as a control. 



"Schlick" or ore slime is a good fertilizer to be 

 used against the disease, according to Hayung.a ( '12, 

 'I.')). .\i)|)el and Schlumberger (13), and Schaffnit 

 and I.ustner ('20). 



