Indiana Plant Diseases, 1922 203 



from normal temperature and rainfall in Indiana in 1922 based upon 

 monthly averages given by J. H. Armington, of the U. S. Weather Bu- 

 reau, in the Indiana section of "Climatological Data." The season of 

 1922 was characterized by high temperatures during all the months ex- 

 cept July and by high rainfall in the spring and low rainfall during May, 

 June, August and September. 



Diseases Arranged by Hosts. 



Alfalfa. — Leaf spot, caused by Pseudopeziza medicuginis, was of 

 general occurrence. Mains reports rust (Uroniyces medicaginis) ex- 

 ceptionally abundant. 



Asparagus. — Rust (Puccinia asparagi) was worse than usual. 



Aster. — Wilt due to Fnsarium conghitinans callistephi was ex- 

 tremely severe owing to the hot dry weather. 



Apple. — Blotch, caused by Phyllosticta solitaria, was very destruc- 

 tive on the susceptible varieties because of the warm wet spring and the 

 failure of many growers to spray the year before. Infection started 

 earlier than in 1920 and 1921 and the spray two weeks after petal fall 

 was too late to pi'event serious infection (3). 



Scab, caused by Venturia inaequalis, was much worse than usual, 

 probably because of the wet spring and the failure of many growers 

 to spray in 1921. The heavy rains in April and a protracted blooming 

 period not only favored scab but also rendered it difficult to apply the 

 sprays on schedule time. Cullinan found scab severe on Grimes, a va- 

 riety usually somewhat resistant to scab, and Burkholder reports that 

 the disease caused early defoliation of an orchard of young Grimes trees. 

 Cullinan found a serious reduction in the size of Ben Davis fruit due to 

 early scab defoliation and found sulfur dust ineffective in controlling 

 scab. The disease was severe on Fameuse, Winter Banana, Ben Davis, 

 Red June, and Delicious. In an orchard of mixed varieties, Grimes, 

 York, and Transparent showed resistance to leaf infection. 



Black-rot, caused by Phi/salospora cydoniae, was widespread and 

 serious. Late summer defoliation due to the leaf lesions was especially 

 harmful and was not controlled by the sprays applied for scab and 

 blotch. In an orchard of mixed varieties, York escaped leaf infection, 

 and Grimes and Benoni showed much less leaf infection than North- 

 western, Wealthy, Chenango, Transparent, Ben Davis, and Jonathan. 

 Shallow bark infection was very conspicuous on old Ben Davis trees in 

 an orchard in Miami County. The extreme heat of early September 

 favored the fruit rot following scab, blotch, and insect injuries on early 

 varieties. 



Fire-blight, due to Bacillus amylovorus, was serious locally in Knox 

 and Franklin counties, possibly due to the warm wet April and subse- 

 quent hot weather. Twig blight was prevalent in young orchards of 

 Transparent, Oldenburg, Jonathan, and Willow. In certain cases, 

 blighted pear trees were the evident source of infection for nearby apple 

 trees. Blister canker, caused by Niimvnda.ria discreta, was favored 

 by the hot dry summer weather. Powdery mildew occurred on young 

 trees in Morgan County. 



