FUNGOID DISEASES OF CRUCIFERS 99 



3. Do not grow seedlings on infected soil, but 

 regulate the moisture in the soil and air so as to 

 have an optimum for plant growth without an excess 

 which favours fungoid growth. 



4. On first appearance remove diseased patch 

 and a coronet of the surrounding healthy plants, and 

 burn. 



5. Deep cultivation has been recommended, as 

 it is said to bury the oospores. 



6. Steeping the seed in various solutions has 

 been suggested, but seeing that the fungus is 

 capable of living as a saprophyte in the soil it is 

 difficult to see how this can be of any use. 



7. Spraying the surface of the soil with Bor- 

 deaux Mixture will sometimes prevent the spread 

 of the disease in the seed bed. 



III. Mildews.— 



(a) True Mildew [Ii7'ysip/ie Martii). Class : 

 AscoMVCETE.E ; Order : Perisporiales. 



(K) False Mildew i^Peronospora parasitica). 

 Class : Phycomvcete.e ; Order : Peronos mor- 

 ales. 



{a) True Mildew. — A species of Erysiphc identi- 

 cal with E. Martii is found on the surface of cruci- 

 ferous plants— for description see under clover 

 mildew, page 63. 



(b) Praise Mildew [Perotiospora parasitica). — • 

 Various cruciferous plants are susceptible, but prob- 

 ably swedes suffer most, especially in dry seasons, 



