PURDUE UNIVERSITY
Agricultural Experiment Station
Circular No. 70 LaFayette, Ind., September, 1917
APPLE DISEASES IN INDIANA
WITH SPRAY SCHEDULE
H. S. Jackson
Every grower of apples realizes the importance of keeping the orchard in a healthy condition, not only with reference to the general vigor of the trees but also with respect to the control of diseases and insect pests. A number of very important diseases are known to occur which cause more or less damage to apple trees or fruit in Indiana. It is the purpose of this circular to furnish in condensed form, information regarding the character, cause and control of the more common and important fungous diseases of the apple, and general spraying directions for the guidance of Indiana orchardists. Several minor diseases of the foliage and fruit are known to occur in Indiana in addition to those included, but it has seemed best to omit them from this circular. Fire blight is discussed in another publication which will be sent free on request.1
Further information regarding the diseases covered in this circular, or of others not mentioned, concerning which growers may desire information, will be gladly furnished at any time. Address the Department of Botany, Purdue University Agricultural Experiment Station, LaFayette, Ind. It is always best when making inquiries concerning plant diseases, to send specimens. These should be ample, and so wrapped as not to dry out during transit.
APPLE SCAB 2
This disease is perhaps the most important of those which affect the apple in Indiana, as is the case in most of the apple growing districts of the United States. It is relatively more important in the northern districts than in the southern, where blotch and bitter rot
1	Durham, C. B. “Fire blight of apples and pears.” Purdue University Extension Leaflet No. 63, 1913. See also, Jackson, H. S., “Fire blight control.” Proceedings Indiana Horticultural Society, 1915. pp. 275-280, 1916
2	Acknowledgment. In preparing the account of the diseases of apples which follow, the writer has drawn freely on all available sources of information, acknowledgment for the use of which is gratefully made. The writer is especially indebted to the Department of Plant Pathology, Cornell University, for the loan of prints from which Figs. 2, 6, 7, 9, 10, 13 and 14 were reproduced, and similarly to the Department of Horticulture, Purdue University for Figs. 3 and 8, as well as for helpful suggestions regarding control measures