Indiana Plant Diseases, 1921 165 



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mildews, corn ear rots, tomato fruit rots following growth cracks, and 

 a local outbreak of buckeye rot of tomato. However, such weather was 

 also particularly favorable to the luxuriant growth of late truck crops 

 and extraordinary yields were obtained this season. The first general 

 killing frost occurred October 13. The long growing season and late 

 fall prolonged the activity and increased the severity of tomato leaf- 

 spot, apple scab, apple frogeye leaf-spot, and the corn ear rots. The 

 corn ear rots were also aggravated by the heavy rains and floods in 

 November. 



Diseases Arranged by Hosts. 



Alfalfa^ — Leaf-spot caused by Pseudopeziza medicaginis was found 

 severe in a field in Marion county and was noted on specimens from 

 Greene county. This disease is co-existent with its host. Gregory noted 

 the leaf-spot caused by Pyrenopeziza medicagmis in Warren county. 

 Mains noted the rust (Uromyces medicaginis) at Lafayette. 



Apple — Since the frost ruined the apple crop in the blotch region 

 (southern Indiana) the blotch sprays were generally omitted and as 

 a consequence of this fact as well as the favorable weather, apple blotch 

 (caused by Phyllosticta solitaria) was especially prevalent on the foliage 

 and on what little fruit remained in the case of the susceptible varieties. 

 Gregory noted fruit infection in Floyd County as early as June 4, and 

 Baker found fruit infection on Northwestern at Knightstown on June 

 10. In an experimental orchard at Laurel, Cullinan noted some blotch 

 infection on Grimes fruit and incriminated a badly cankered North- 

 western tree near by as the source of infection. Cullinan also found 

 a few fruit lesions on Stayman in a young orchard near Lafayette on 

 Sept. 28, and the source of infection here was not located. In an orchard 

 near Mooresville there was spread of infection from q row of badly cank- 

 ered Northwestern to the fruit of the varieties Ben Davis, Stark, York, 

 Grimes, and Jonathan. It was rather severe on the York. A few fruit 

 lesions on Ben Davis were noted at Peru, and a few cankers were noted 

 on Oldenburg and Stark trees in Miami County. In an orchard of 

 young Oldenburg trees at Vincennes, the occurrence of old blotch can- 

 kers scattered here and there was indicative of blotch introduction 

 with nursery stock. 



In an orchard of mixed varieties near Mitchell, a row of Oldenburg 

 trees was very heavily infected. Observations on the adjacent trees of 

 other varieties revealed a few blotch cankers on the varieties Akin, Ben 

 Davis, Champion, Gideon, Summer Rambo, and Salome. In each case 

 these cankers were on the side of the tree next to the Oldenburg trees. 

 Blotch seemed, however, to be enphytotic in one isolated Summer Rambo 

 tree. Single trees of the varieties Winesap, Delicious, Wealthy and 

 Celestia, as well as two Salome trees similarly exposed to the Olden- 

 burg row, showed no cankers. 



The Bordeaux blotch sprays (2, 4, and 6 weeks after petal fall) 

 again gave good control of fruit infection on Northwestern at Knights- 

 town, and practically perfect control of leaf infection in this orchard 

 as well a::, on the same variety at Mooresville, on Oldenburg at Mitchell, 

 and on Ben Davis at Solon. In all cases, leaf petiole infection on un- 



