Minnesota Plant Diseases. 



;i9 



cutting and burning, injures the asparagus. Ordinary bor- 

 deaux mixtures have been tried but with Httle success. Resin 

 bordeaux is recommended by the New York Agricultural Ex- 

 periment Station where the rust has been successfully treated 

 with this mixture. The application with ordinary barrel pumps 

 is too laborious and slow, so that it was found necessary to de- 

 vise a special sprayer, the plans and description of which are 

 published in the bulletins of that station. (See N. Y. Ex. Sta. 

 Bull. No. 1 88.) Sulphur has very recently been shown to be 

 quite successful in keeping down the disease in California. 



Bean rust [Uromyces appendiculatus (P.) Link.]. This is not 

 usually one of the most serious of bean diseases, but may in 



some localities become a dan- 

 gerous pest. It attacks chief- 

 ly the common garden bean, 

 but has also been reported on 

 other beans. All three spore 

 forms occur on the same host 

 plant. The cluster-cups are 

 yellowish and appear in the 

 late spring. The summer and 

 winter spores appear later in 

 small pustules, about the size 

 of a pinhead. These pustules 

 are light- to dark-red-brown 

 and appear chiefly on the leaf- 

 blades but can also be found 

 on the petioles, stems and 

 even on the pods. The pus- 

 tules are circular in outline 

 and the spore masses of summer and winter spores are powdery. 

 The winter-spore pustules are dark-brown and may finally be- 

 come blackish in color. The winter spores are single-celled 

 and germinate in the usual method for rust winter spores. 



Certain varieties of bean resist the rust and such should be 

 planted. Infected plants should be destroyed by burning. 

 Bordeaux mixture has also been suggested as a means of hold- 

 ing the disease in check, but is not in general use. 



Fio. 162.— Rust of bean. Winter spore clus- 

 ters on the lower surface of a bean leaf. 

 After Clinton. 



