UNITED STATES DEPARTMENT OF AGRICULTURE 



f BULLETIN No. 1116 ^M 



WASHINGTON, D. C. PROFESSIONAL PAPER November 13, 1922 



SEEDLING BLIGHT AND STACK-BURN OF RICE AND 

 THE HOT-WATER SEED TREATMENT. 



By W. H. TiSDALE, Pathologist in Charge of Smut Investigations, Office of Cereal Inves- 

 tigations, Bureau of Plant Industry. 



CONTENTS. 



Page. I Page. 



Introduction 1 [ Causes of injury 3 



Factors favoring the development of this dis- j Seed treatment 6 



ease 2 Conclusions 10 



INTRODUCTION. 



The rice crop of the southern part of the United States suffers 

 heavy annual losses due to the staining and decay of the grain in the 

 shock and in storage, both before and after milling, and to poor 

 germination of the seed when sown. The former is much more 

 important than the latter. Occasionally fields have to be reseeded, 

 and others have poor stands. The milled product, on the other hand, 

 is considered of inferior quality if only a low percentage of the grain 

 is flecked or decayed. Van der Wolk,* in discussing the trouble 

 known to the European rice trade as ''yellow grains," says that it 

 is ''one of the most fearful calamities in the trade rice of some coun- 

 tries." "Yellow grains " is similar to the stains which develop in our 

 southern rice. It is caused by a different fmigus, which accounts 

 for the difference in color. The disease appears in our American 

 rices as flecks or totally decayed grains which are yellowish brown to 

 dark brown in color. The term "stack-burn" often is applied to this 

 form of injury by rice growers and millers. "Stain" and "flecking" 

 are other terms used. 



The decay of rice seed in the soil and the staining and decay of the 

 commercial product make investigations for determining causes and 



1 Wolk, P. C. van der. Protoascus colorans, a new genus and a new species of the Protoascineae group, 

 the source of "yellow grains' in rice. In Mycol. Centralbl., v. 3, no. 4, p. 153-157, 1 col. pi. 1913. 

 3866°-22— Bull. 1116 



