SEEDLIXG BLIGHT AXD STACK-BUEN OF EICE. 



CAUSES OF INJURY. 



The seed-injury phase and symptoms of the trouble were touched 

 upon previously by Godfrey,^ who reported the occurrence of a leaf- 

 spot on rice in Louisiana in 1916. He said the disease looked very 

 much like the black rust of cereals. Again in 1920, after the writer's 

 investigations were begun, Godfrey^ reported the occurrence of a 



seedling disease of rice and 

 states that the cause was 

 found by Dr. H. B. Hum- 

 phi'ey to be due to an or- 

 ganism belonging to the 

 Mycelia sterilia group of 

 fungi. The fungus was 

 characterized by very small 

 black sclerotia and a white 

 sterile m^ycelium. He fur- 

 ther states that the fungus 

 closely resembles the Sclero- 

 tium found associated with 

 the leaf disease reported in 

 1916. Godfrey found the 

 fungus constantly associated 

 with rice seed grown in 

 Louisiana, particularly the 

 Blue Rose and Honduras 

 varieties. California seed, 

 however, was found to be 

 free from the fungus. 



The cause of these troubles 

 was found to be much more 

 comphcated than the notes 

 by Godfrey would seem to 

 indicate. Van der Wolk 

 found the fungus Protoascus 

 colorans to be responsible for 

 yellow grains . " * The col- 

 or appeared after the rice 

 had been in heaps for considerable lengths of time. The writer found the 

 small sclerotial fungus of the Mycelia sterilia group mentioned by God- 

 frey^ to be constantly associated with the leaf -spot (Fig. 1) mentioned by 



2 Godfrey, G. H. Preliminary notes on heretofore unreported leaf disease of rice. (Abstract.) In 

 Phytopathology, v. 6, no. 1, p. 97. 1916. 



» Godfrey, G. H. A seed-bome Sclerotimn and its relation to a rice-seedling disease. In Phytopath- 

 ology, V. 10, no. 6, p. 342-343. 1920. 



« Wolk, P. C. van der. Opl cit. 



Fig. 1.- 



—Black leaf-spot of rice caused by the sclerotial fungus 

 which produces seed injury and seedling blight. 



