148 ILLINOIS STATE ACADEMY OF SCIENCE 



many cases, be made because there was practically no 

 crop on tliose plants. 



DISEASES WOKTHY OF NOTE IN 1921 



It is worth while calling attention to certain diseases 

 which, during the past season, were especially destructive 

 either in state wide or in local epiphytotics. 



At Libertyville, in Lake county, red raspberry plant- 

 ings were suffering severely from an attack of physiolo- 

 gical leaf curl. This disease is known commonly among 

 growers as ''yellows" and as "Marlboro disease". 

 There is no known cause for the disease, and effective 

 treatments are unknoAvn. While this disease is not widely 

 distributed through Illinois at present, wherever it has 

 appeared it has been one of the most serious diseases of 

 the raspberry. The losses from this disease in the se- 

 verely infested raspberry plantings in Lake county has 

 been estimated to be nearly 90% of the total crop. 



Several patches of strawberries in Lake county were 

 injured to the extent of a 50% crop loss through the at- 

 tack of the strawberry leaf spot caused by Mycosphae- 

 rella fragariae. 



The Physoderma disease of corn, while prevalent 

 throughout the southern half of the state, was nowhere 

 severe with the exception of an area around Eureka in 

 Woodford county, where the disease was reported as 

 doing considerable damage. Samples received and ex- 

 amined by us were so severally diseased that we feel justi- 

 fied in estimating a loss of at least 25% in this area. This 

 is especially remarkable in view of its northness. 



In all of the cabbage growing sections of the state, the 

 disease known as cabbage yellows, caused by Fusarium 

 conglntinans , was the cause of an important reduction in 

 the yield of the cabbage crop. Damage was particularly 

 heavy in the Peoria district, and in the small gardens of 

 Champaign County. 



In Coles county, black knot of plum, caused by Plow- 

 rightia morhosa, appeared in rather more than its usual 

 destructive abundance. In the same county broom corn 

 blight, caused by Bacillus sorglii, appeared to be damag- 

 ing beyond use about 1% of the plants in the fields, but 



