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INDIANA PLANT DISEASES, 1920." 
Max W. GARDNER.’ 
INTRODUCTION. 
In accordance with the plan outlined in last vear’s report,’ the plant dis- 
ease situation in Indiana for the season of 1920 is summarized herein as 
completely as our reports and observations permit. As in the previous 
report, the economic point of view is maintained. 
WEATHER CONDITIONS. 
The important relation of the weather to crop diseases warrants a brief 
report based upon the monthly summaries of Mr. J. H. Armington of the 
federal weather bureau at Indianapolis. 
The extremely cold, wet weather of April delayed farm operations and 
retarded crops several weeks. The first half of May was aiso very cold, 
culminating in frosts the 14th and 15th which caused considerable injury 
to fruit. In some localities seed potatoes rotted in the ground because of 
the cold wet weather. 
The latter part of May and all of June and July were in general favorable 
to crops. June and July were exceptionally cool and rainfall was fairly 
abundant. Severe hail injury occurred at Vincennes, June 1, at Madison, 
June 14, and at Kokomo, Berne and Decker the 23rd. At Decker the in- 
jury to corn, wheat, oats, tomatoes, melons, peaches and apples caused a 
loss estimated at 150,000 dollars. 
August was also fairly cool and the whole summer up to the end of 
August was characterized by the absence of any period of heat and 
drouth. This type of weather greatly lessened the destructiveness of the 
Fusarium soil diseases such as cabbage yellows and favored the preva- 
lence of such diseases as Septoria leaf-spot of tomato. 
September was very hot especially during the latter half with less rain- 
fall than in previous years in central and northern Indiana and dry 
warm weather continued well into October. This type of weather favored 
the ripening of fall crops and at the same time was not especially conducive 
to plant diseases. Light frosts occurred October 20 and heavy frosts the 
end of the month. 
In general the 1920 season was distinctly different from its prede- 
cessor and the difference in weather is rather strikingly reflected in the 
plant disease conditions. 
Contribution from the Botanical Department, Purdue Agricultural Experiment 
Station, Lafayette, Indiana. 
2The writer wishes to acknowledge the assistance of Prof. H. S. Jackson, Mr. F. 
J. Pipal, Mr. G. N. Hoffer, Mr. J. B. Kendrick, Dr. C. T. Gregory and Dr. E. B. 
Mains of the Botanical Department and Messrs. C. L. Burkholder, F. P. Cullinan, 
F. C. Gaylord and H. D. Brown of the Horticultural Department of Purdue Agricul- 
tural Experiment Station. Most of the illustrations are taken from photographs 
made by Mr. Kendrick. ‘ 
_ *@Gardner, Mar W. Indiana plant diseases, 1919. Proc. Ind. Acad. Sei. 1919, 
in press. 
