146 ILLINOIS STATE ACADEMY OF SCIENCE 



co-operation with Dr. H. W. Anderson are presented in 

 summary below : 



Summary of fruit, vegetable, and ornamental diseases 

 for 1921. 



FRUITS. 

 APPLE: 



Bitter rot (Glomerella cingulata) — Local damage averaging 1% in 

 orchards planted to late varieties in southern part of state. 



Black rot (Physalospora cydoniae) — Distributed throughout the 

 state. Loss approximately 2%, chiefly through rotting of wormy fruit. 



Blister canker (Nummularia discreta) — Generally distributed 

 throughout the state, but more severe in southern Ben Davis orchards. 



Blotch (Phj'llosticta solitaria) — Distribution general southward, 

 present locally northward. Reduction in yield about 5%. 



Brown rot (Sclerotinia cinerea) — Appeared generally throughout 

 the state, chiefly on wormy fruit, causing only a trace of damage. 



Blight (Bacillus amylovorus) — Attacks were chiefly local and more 

 severe northward. Damage about 1%. 



Cedar rust (Gymnosporangium juniperi-virginianae) — Present 

 chiefly south and westward. Damage only a trace, due chiefly to leaf 

 injury. Occurring especially on Benoni, York, and Wealthy. 



European canker (Nectria galligena) — Not generally distributed. 

 Only one case reported. Little if any damage. 



Fruit spot (Phoma pomi) — Present in the state but not generally 

 distributed. No damage. 



Potvdery mildeiv (Podosphaera leucotricha) — Widely distributed 

 throughout the state, but important only in nurseries. Crop damage 

 little if any. 



Bough bark (Phomopsis mali) — Probably widely distributed 

 though not commonly reported. No appreciable damage. 



Scab (Venturia inaequalis) — The most important apple disease. 

 Distribution general, with 95% of the orchards of the state infected. 

 An estimated reduction in yield of from 10 to 15%. 



Root rot (Xylaria sp.) — Present locally in extreme south, not an 

 important disease. 



• Root rot (Armillaria mellea) — Rare in Illinois. No appreciable 

 damage. 



Jonathan spot — A very important disease on Jonathan apples. 

 Distribution general. 



Measles — First reported last season. Not now important. 



Cracking (due to weather conditions) — Serious locally on Stay- 

 man's winesap. 



PEAR: 



Blight (Bacillus amylovorus) — Loss very slight. Present mostly 

 as twig blight which was checked by hot weather of June and July. 



Leaf spot (Fabraea maculata) — Very important disease. Present 

 in epiphytotic form in Marion and Union counties. Especially severe 

 on French seedling stock in nurseries. 



Leaf spot (Mycosphaerella sentina) — No loss. Appeared late in 

 the season. 



PEACH: 



Bacterial leaf spot (Bacterium pruni) — Distribution general. 

 Some losses locally resulting from defoliation. 



