Aug. x, 1921 
Two Sclerotium Diseases of Rice 
657 
ing, mentioned by Shaw 1 and Butler 2 in India. This condition does not 
occur in this country to any noticeable extent and is not mentioned by 
Miyake 3 in Japan. This perhaps is due to earlier attacks by the fungus 
in India, which cause the injured plant to produce tillers. All other 
evidence indicates that the disease in the various countries is caused by 
Sclerotium oryzae. The fungus was probably introduced into America 
with seed rice from some of the oriental countries. 
Honduras rice plants were inoculated by inserting mycelium of the 
fungus into needle punctures in the stem tissues near the water surface. 
Within 11 days there were noticeable lesions, and one plant had fallen 
from stemrot. One month after inoculation all plants were diseased, 
and sclerotia were present in the diseased tissues of some of them. 
Shaw 1 reports 70 to 80 per cent of fatalities to rice seedlings grown on 
nutrient agar and inoculated with the fungus. 
In 1920, the disease did considerable damage to early rice in the 
vicinity of Crowley, La., where it was first noted in this country. Early 
Prolific rice is especially susceptible to its attack, but all varieties were 
more or less affected. The disease was found also at Elton, La., where 
it did noticeable damage in 1920. Reports of its occurrence in Arkansas 
have been received, but specimens have not been obtained for identifica¬ 
tion. Cattaneo 4 states that the disease was destructive in Italy as 
early as 1879. Miyake 3 reports its occurrence in Japan in 1910 and 
says great damage is caused to the rice crop where diseased. Shaw 1 
and Butler 2 in 1913 report considerable damage in various localities in 
India due to this disease. 
During the winter and other periods unfavorable to growth the fungus 
survives in the sclerotial stage. The sclerotia from old rice straw and 
stubble germinate readily in the spring. These sclerotia can be carried 
easily from field to field by the irrigation water on which they float. 
Straw removed from the diseased areas also will carry the fungus. 
The Japanese varieties apparently are less susceptible to the disease 
than are the long-grain rices. Early Prolific seems to be the most 
susceptible of all. There is a possibility of developing a resistant variety 
by selecting plants which withstand the attacks of the fungus. All 
diseased plants should be carefully removed from plots where seed rice 
is to be obtained. Where the soil is infested with the fungus the more 
resistant varieties should be grown in preference to varieties that are 
known to be highly susceptible. 
1 Shaw, F. J. F. op. cit. 
3 Butler, E. J. diseases op rice. In Agr. Research Inst. Pusa Bui. 34, p. 34-36. 1913. 
8 Miyake, Ichiro, studien uber die pilzE der reispplanze in japan. In Jour. Col. Agr. Imp. 
Univ. Tokyo, v. 2, no. 4, p. 264. 1910. 
4 Cattaneo, Achille. op. cit. 
50936°—21 - 4 
