PAPERS ON BIOLOGY AND AGRICULTURE 251 



state. It is estimated to have caused damage to trees 

 equivalent to a crop loss of 1 per cent. 



Blotch (Phyllosticta solitaria E. & E.) appears com- 

 monly as far north as Champaign county. Year by year 

 it is migrating northward. A crop reduction of at least 

 5 per cent is attributed to it. 



Brown rot (Sclerotinia cinerea (Bon.) Schroet.) was 

 found July 13, near Francis, in Saline county, and was 

 found later in Jackson, Monroe and Randolph counties. 

 It occurred only sparingly, and caused little if any re- 

 duction of the crop. 



Rust (Gymnosporangium juniperi-virginianae Schw.) 

 was less abundant than usual, and appeared chiefly on the 

 leaves. It occurred throughout the southern half of the 

 state. It was reported to be severe on the Mississippi 

 bluffs in TThiteside county, and near Martinsville in 

 Clark county. The crop reduction is estimated as 1.5 per 

 cent. There appears to be a general correlation between 

 the range of cedar infection in the state and the range 

 of the rust on the apple. 



Crown gall (Pseudomonas tumefaciens E. F. S.) was 

 reported from "Williamson county. 



Fire blight (Bacillus ainylovorus (Burr.) Trev.) oc- 

 curred in every county in the state. It was more abund- 

 ant than last season, but occurred chiefly as leaf and twig 

 blight. The crop reduction is estimated to have been not 

 more than 1 per cent. 



Fly speck (Leptothyrium pomi (Mont. & Fr.) Sacc.) 

 was generally distributed. A few instances of severe in- 

 fection with consequent serious defacement of the fruit 

 appeared in the extreme south. 



Leaf spot (Septoria pyricola Desm.) was found in 

 Jackson, Saline, Union and Pulaski counties. Two re- 

 ports show 100 per cent and 40 per cent respectively of 

 infected leaves on the trees. So far as we can determine, 

 this appears to be the first report of the occurrence of 

 this disease in Illinois. 



Powdery mildew (Podosphaera leucotricha (E. & E.) 

 Salm.) was not abundant and caused very little damage. 



Scab (Venturis inaequalis (Cke.) Wint.) was severe 

 locally and was present in its usual abundance through- 



