SEEDLING BLIGHT AlsTD STACK-BURN OF RICE. 5 



color. Dark bands of sclerotial tissue may be seen on kernels in- 

 fected with the sclerotial fungus. 



The climatic conditions in the rice-growing sections of the South 

 favor the development of these troubles. The humid atmosphere 

 and high temperatures are conducive to a vigorous growth of the 

 various fungi concerned, and the humidity is unfavorable for the 

 drying and curing of rice, thus leaving it exposed to attacks by these 

 organisms. The drier atmosphere and the rather low night tempera- 

 tures which generally prevail in the rice-growing sections of Cali- 

 fornia during the crop season probably are not favorable to the 

 development of most of these fungi. 



There is one type of flecking known as ''blast" in California. In 

 1919 seed of this type collected at various points in the State was 

 found to contain an Alternaria in the diseased spots. Brown spots 

 or totally brown glumes characterize this trouble. The kernels are 

 also yellowish to brown in color beneath the diseased glumes. Some 

 of the spots have lighter colored centers. The fungus might have 



been growing as a 

 saprophyte in these 

 dead areas, but the 

 failure to find it associ- 

 ated as constantly with 

 healthy kernels seems 

 to indicate that to 

 some extent it was 

 responsible for the in- 



FiG. 2.— Camera-Iucida sketch of the germ tube from an Alternaria ]Ury. When these 

 spore penetrating the epidermis of the leaf of a rice seedling. kernels Were dehulled 



surface sterilized, and placed in damp sterile chambers the spots 

 increased in size, and a growth of Alternaria appeared on the surface. 

 Alternaria also was isolated from rice seed grown in Louisiana. 



In Louisiana a leaf spotting of seedlings was noticed as being 

 quite common before the irrigation water was applied. The spots 

 were small, indefinite in outline, and light brown in color. An Alter- 

 naria was found constantly associated with those spots. By examin- 

 ing carefully under the microscope these young leaves, cleared by 

 soaking in equal parts of 95 per cent alcohol and glacial acetic acid, an 

 Alternaria spore could be seen in the center of almost every spot, and 

 often the germ tube could be seen extending from the spore and 

 passing through the epidermis into the leaf tissues (Fig. 2). An 

 Alternaria leaf-spot of black Italian rice and of C. I. No. 1564 was 

 found at Bellflower station, near Los Angeles, Calif., but it was not 

 determined whether or not this was identical with the form producing 

 the "blast" of rice kernels in the Sacramento Valley or with the 



3866°— 22 2 



