UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1482 
Washington, D. C. 
April, 1927 
EXPERIMENTS ON THE CONTROL OF THE PLUM CURCULIO, BROWN ROT, 
AND SCAB, ATTACKING THE PEACH IN GEORGIA 
By Oliver I. Snapp, Associate Entomologist, and C. H. Alden, Assistant Ento- 
mologist, Fruit Insect Investigations, Bureau of Entomology; John W. Roberts, 
Pathologist, and John C. Dunegan, Assistant Pathologist, Fruit Disease Inves- 
tigations, Bureau of Plant Industry; and J. H. Pressley, Field Agent, Georgia 
State Board of Entomology x 
CONTENTS 
Page 
Introduction 1 
The Georgia peach belt 2 
Relative abundance of the curculio in Geor- 
gia from 1920 to 1924 2 
Climatic conditions and curculio behavior... 4 
Experiments on spraying and dusting in the 
Georgia peach belt 8 
Experiments in 1921 9 
Experiments in 1922 10 
Page 
Experiments on spraying, etc.— Continued 
Experiments in 1923 14 
Experiments in 1924 22 
Conclusions 29 
Recommendations for spraying and dusting. 31 
Spraying schedule 31 
Dusting schedule 32 
Literature cited _. 32 
INTRODUCTION 
Perhaps the most severe infestation on record of the plum curculio 
(Conotrachelus nenuphar Hbst.) on the peach was experienced in 
Georgia in the season of 1920. Owing to the abundance and destruc- 
tiveness of the insect that year, only a small proportion of the Georgia 
Belle and Elberta peaches could be marketed, the larvse having 
rendered the greater part of them unmerchantable. Much of the 
fruit that was shipped in 1920 arrived at its destination greatly 
damaged by curculio larvse, as in many cases wormy peaches were 
packed because the presence of the tiny larvae just hatched could not 
be detected. It has been conservatively estimated that the curculio 
alone damaged the Georgia peach crop of 1920 to the extent of 
$2,000,000. The very heavy infestation of that year also provided 
innumerable punctures in the skins of the fruit, through which the 
brown-rot fungus, Sclerotinia fructicola (Wint.) Rehm, 2 gained easy 
access and frequently finished the work of destruction begun by 
the curculio. Since the peach crop of 1919 had also been a partial 
» The authors are indebted for assistance to John B. Gill (1921) and W. D. Whitcomb (1921), of the 
Bureau of Entomology; Lee M. Hutchins (1921), of the Bureau of Plant Industry; and William F. Turner 
(1921-22) and Luther Brown (1923), of the Georgia State Board of Entomology, who have respectively 
helped to conduct the work during the seasons indicated. 
2 Other names which have been applied to this fungus are Sclerotinia fructigena, S. cinerea, S. cinerea 
forma americana, and S. americana. 
29519°— 27 1 
