249 



Downy Mildew 

 Caused by Pseudoperonospora cubcnsis (B. & C.) Rostow 



The downy mildew disease appears as a leaf spot, which may be very 

 destructive under favoring conditions. It was rejiorted by Burrill to 

 have occurred in Union and Effingham counties in 1911, and this is our 

 only report of its presence in the state. 



Angular Leaf-spot 

 Caused by Psendomonas lachrymans E. F. S. and Bryan 



The angular leaf-spot of cucumber, caused by a bacterium, is not 

 known to have occurred in Illinois previous to 1923. During that sea- 

 son, it was seen occasionally in Union county and once in Pulaski county. 

 In a 5-acre field in Alexander county [jraclically all the plants were dis- 

 eased, but the infection was light and little damage resulted. 



Asparagus 



The land devoted to asparagus-growing in Illinois averages annually 

 nearly 2000 acres for commercial production, and the annual yields per 

 acre is above 9.j crates. The annual yield of the state for commercial 

 purposes is about 332 cars of 000 crates each. Illinois ranks either 

 second or third in conmiercial production, and California is the only 

 state which greatly exceeds it. 



Asparagus is subject to two diseases in Illinois, both important, not 

 only to the commercial grower, but to the many gardeners who cater to 

 local markets, and in the home garden. 



Rust 

 Caused by Puccinia asparagi DC. 



Asparagus rust is widely distributed and often serious in its effects. 

 It has the ai)i)carance of the rust described on other ])lanls. 



It is not known how long this disease has been iircscnt in Illinois, but 

 it was probably first recorded here in I,s99. Since tliat time it has been 

 frequently seen and reported. 



It is now known in 30 counties, distributed over the state as shown 

 on Map 109. It appears prevalent in two sections of the state — one in 

 southern and one in northern Illinois, and its presence in Champaign, 

 Edgar, and Coles counties probably indicates a wider distribution. 



Its control lies in the use of varieties not susceptible to rust. Among 

 these are the Palmetto varieties and resistant strains of Washington 

 asparagus. .Additional control may be gained by dusting with sulfur or 

 spraying with sulfur-soda-soap. 



