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| UNITED STATES 
DEPARTMENT or AGRICULTURE 
DEPARTMENT CIRCULAR 376 
Washington, D. C. January, 1 926 
A METHOD FOR THE CONTROL OF CROWN 
GALL IN THE APPLE NURSERY 
M. B. WAITE 
Senior Pathologist in Charge; and 
E. A. SIEGLER 
Assistant Pathologist, Office of Fruit-Disease Investigations, Bureau of Plant Industry 
CONTENTS 
Page Page 
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Experiments and results__________-- 2 | Recommendations for control________ 6 
INTRODUCTION 
The problem of crown gall in the root-grafted apple nursery is a 
very serious one. The nurseryman who has to discard only 5 to 10 per 
cent of his trees on careful inspection at digging time is usually 
considered fortunate. Losses of 25 to 50 per cent are not uncommon, 
and certain lots of trees in extreme cases have even shown a loss 
of 95 per cent. ‘These serious losses to nurserymen and also the 
general interest of orchardists in obtaining disease-free stock for 
ylanting have made the writers feel the importance of this phase 
of the crown-gall problem. Present-day nursery stock, especially 
when grown by the root-grafting method, appears to contain a 
higher percentage of infection than formerly, and there also appears 
to be more trouble in recently planted apple orchards than in those 
planted a generation ago. Whether this supposition is true or not 
may be open to question. It may be that nursery and orchard trees 
are examined more critically as increased attention is given to 
orchard diseases. 
Before the bacterial cause of this disease was known George G. 
Hedgcock, in his extensive studies of crown gall, tried many experi- 
ments in the propagation of root-grafted apple trees and made many 
observations which resulted in progress toward the control of this 
disease. The discovery of the bacterial nature of this previously 
7TH646—26 
