Family Chenopodiaceae 123 



tion will greatly help to control the rot on the ma- 

 ture roots. To prevent seedlings from damping off 

 care should be taken that no hard crust be allowed to 

 form on the soil. After a rain the soil should be 

 worked as soon as possible. 



White Rust 



Caused by Cystopus bliti (Biv.) Lev. 



This disease is of little economic importance as far 

 as the trucker is concerned. Its occurrence on beets 

 has been reported but once by Pammel. J In appear- 

 ance, infected leaves show white raised pustules or 

 sori on the under side. When the surface cover of 

 the pustules bursts open a powdery mass of snow- 

 white spores is liberated. The same disease also 

 attacks ' ' pigweeds. ' ' Clean culture is recommended. 



Downy Mildew 



Caused by Peronospora schachtii Fckl. 



This disease, like white rust, is of little economic 

 importance in the United States. The trouble, 

 however, is very prevalent in Europe. The mildew 

 attacks the young seedlings in grayish patches on 

 the under side of the foliage. On older plants the 

 mycelium of the causative fungus works down- 

 wards into the root where it is carried over winter 

 (fig. 20c- f). 



1 Pammel, L. H., Iowa Agr. Expt. Sta. Bui. 15 : 234-254, 1891. 



