UNITED STATES DEPARTMENT OF AGRICULTURE 



BULLETIN No. 531 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



S\i&"&SU 



Washington, D. C. 



PROFESSIONAL PAPER 



May 28, 1917 



RHIZOPUS ROT OF STRAWBERRIES IN TRANSIT. 



By Neil E. Stevens, Pathologist, and R. B. Wilcox, Scientific Assistant, 

 Fruit-Disease Investigations. 



CONTENTS. 



Page. 



Introduction 1 



Causes of decay in transit 2 



Conditions of transportation 2 



Condition of fruit 2 



Fungi 4 



Rhizopus nigricans 4 



Physiology of Rhizopus nigricans 7 



Character of the rot produced 7 



Humidity relations 7 



Temperature relations 7 



Host relations 9 



Occurrence on other plants 9 



Present shipping practices 11 



Sources of infection by Rhizopus nigricans. . 13 



Infection in the field 13 



Unsanitary conditions usually prevailing 



in the packing house 14 



The bruising of berries in packing 14 



Direct sources of infection 15 



Washing berries 15 



Drying berries after washing 16 



Summary 19 



Literature cited 21 



INTRODUCTION. 



The increased production of strawberries in the Southern States 

 has resulted in large shipments to northern markets. These ship- 

 ments have been attended by great losses, due to the decay of the 

 fruit in transit and on the market. In the hope of obtaining infor- 

 mation which will assist in reducing this large annual loss, Dr. C. L. 

 Shear and the writers began, in 1915, a study of the organisms and 

 conditions causing decay of strawberries after picking. 



This study has included field observations in the principal straw- 

 berry-growing regions of Florida, Louisiana, North Carolina, Vir- 

 ginia, Maryland, and Delaware ; observations in the markets of Bos- 

 ton, New York, Philadelphia, and Chicago; laboratory studies of 

 the organisms causing strawberry rot; and experimental shipments 

 from points in Florida and Louisiana. 1 These shipments were 



1 Through the cooperation of Mr. George M. Darrow, of the Office of Horticultural and 

 Pomological Investigations of the Bureau of Plant Industry, the writers have received 

 strawberries from points in Alabama, Louisiana, Texas, and other States at times when 

 it was impossible for them to visit these regions. The writers are also indebted to 

 numerous fruit growers and shippers, especially in the central Florida region, for 

 assistance. 



Note.— This paper is of interest to botanists, pathologists, and strawberry growers and shippers, 

 especially in the Southern States. \ 



80315° — Bull. 531 — 17 



