122 MISSOURI BOTANICAL GARDEN 



Humphrey* reports it growing on purple topped white 

 turnips together with Cystopus candidus (Pers.) Lev. 



t 



tive 



P 



Albugo Candida (Pers.) O. Kze. ( 



(opus candidus, Pers., Lev.) whieh are generally found 

 together. " This disease attacks turnips, mustard, kale, 

 collards, and various weeds belonging to the collard tribe, 



especially shepherd's purse or pepper grass." 



The only case which appears to have been reported of the 

 occurrence of this fungus on cauliflower, in a destructive 

 manner, is cited by Marchal,J who states that Peronospora 

 caused much loss in France to market gardeners, erowino- 

 cauliflower that winter. 



In the case of the plants of the Missouri Botanical Garden, 

 the fungus made its appearance on the under side of the 

 younger leaves (plate 23), distributed in irregular patches 

 over the entire surface of the leaves. The areas inimedi- 

 ately affected by the fungus turned white, giving the cauli- 

 flower a speckled appearance, as shown in plate 22. 



The fungus grew rapidly through the tissues and after 

 several days the entire leaf was usually affected. In the 

 later stages the leaves dried considerably and became much 

 torn and shriveled, as shown on plate 24. 



Combative measures against this fungus have usually 

 been attended with considerable success. McCarthy (loc. 

 cit.) recommended removing all Cruciferae, as far as pos- 

 sible, from the fields, and treating the compost and stumps 

 with lime. The plants themselves, he advises treating in 



o 



the seed bed with iron sulphate, potassium sulphide, or 



* Humphrey, J. E., 7th Report, State Agr. Exp. Sta., Amherst, Mass., 

 page 222. 



f McCarthy, Gerald, Bull. N. C. Exper. Station, No. 84, pg. 15.(1892). 



I Marchal, E., Report on fungus diseases studied at the Agricultural 

 Inst, of Gembloux during 1900. (Bull. Agronomique. Brussels. 

 17: 4-18. 1901.) 



L 



