Indiana Plant Diseases, 1921 163 



INDIANA PLANT DISEASES, 1921.^ 



Max W. Gardner', Purdue University. 



This is the third of a series of annual reports (16, 17 )^ the object 

 of which has been to summarize the plant disease situation in Indiana. 

 This report is based upon our records and observations during the sea- 

 son of 1921 and the plan outlined in the 1919 report (16) has been fol- 

 lowed. As in these previous reports, no claim for completeness is made. 

 Of necessity, our attention has been confined largely to agricultural crops 

 and the diseases of economic importance. The diseases are arranged 

 alphabetically by hosts except that under the headings, "Forest and 

 Shade Trees" and "Ornamentals", near the end of this report are 

 grouped such fragmentary records as we have relative to the diseases 

 of such plants. For further information relative to parasitic fungi in 

 Indiana the papers by Jackson (27, 28), Anderson (1), and Van Hook 

 (41), should be consulted. Many of the diseases are well illustrated in 

 the annual reports of the State Entomologist of Indiana, 1907 to 1916.' 

 The geographic distribution and economic importance of the various 

 Indiana crops have been reported by Bryant (6). 



Weather Conditions. 



The season of 1921 in Indiana was characterized by most peculiar 

 weather conditions. The winter of 1920-21 was exceptionally mild and 

 open. The graphs in figure 1 illustrate the departures from normal 

 temperature and rainfall during the growing season based upon the 

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

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



These figures show that March and April were exceptionally warm 

 and wet, while during late May, June and July, the weather was espe- 

 cialy hot and dry, culminating in a destructive drouth in July. The 

 marked feature of the summer, however, was the very high rainfall dur- 

 ing August and September with a very high temperature for the latter 

 month. This resulted in truly tropical conditions which, of course, 

 exerted a marked influence on the plant disease situation in Indiana. 



The mild, open winter probably favored the severe attack of rye 

 anthracnose in northern Indiana, the fungous foot-rot of rye and wheat, 

 and the wheat leaf rust epiphytotic in southern Indiana. The unusually 

 warm, early, and wet spring probably increased the severity of rye 

 anthracnose, raspberry anthracnose, strawberry leaf-spot, early infec- 

 tion of apple scab, apple blotch, peach bacterial spot, and black-leg on 

 cabbage seedlings. The late frosts of March 29, April 10-11, and April 

 18 completely ruined tree fruits in central and southern Indiana. Not 

 so much damage was done in the northern part of the state. 



^ Contribution from the Botanical Department, Purdue University Agricultural Ex- 

 periment Station, Lafayette, Indiana. Presented at the 1922 meetins'. 



- The writer wishes to acknowledge the assistance and co-operation of H. S. Jackson, 

 E. B. Mains, J. B. Kendrick, G. N. Hoffer, C. T. Gregory and R. J. Hosmer, C. L. 

 Burkholder, F. P. Cullinan, F. C. Gaylord, H. D. Brown, I. C. Hoffman and C. E. Baker. 



^ Numbers in parenthesis refer to "literature cited". 



"Proc. Ind. Acad. Sci., vol. 33, 1923 (1924)." 



