6 5 4 
Journal of Agricultural Research 
Vol. XXT, No. 9 
Two inoculated cans and one control can from each series were irrigated 
at a depth of 4 to 5 inches 20 days after planting, and none of the plants 
died after the irrigation water was applied. Plants which showed signs 
of the disease revived rapidly after the application of the water. About 
7 weeks after sowing the plants were removed from the remaining seven 
cans in each series, and the cans were resown. The Plonduras variety of 
rice was used, as in previous experiments, and 100 seeds were sown in 
each can. Can No. 5 in each series was reinoculated with fresh cultures 
of the same organisms used with the previous sowings. Results of these 
experiments are given in Table II. 
The results given in Table II indicate that the fungus is practically 
exhausted after eight weeks in the soil where rice is grown. Soil that 
was reinoculated (can No. 5) in each case showed the same proportionate 
decrease in germination as was shown in Table I. 
endurance of the; fungus 
The fungus remains in the sclerotial stage during seasons that are un¬ 
favorable to growth. The mycelium will live for considerable lengths 
of time in the infected plant tissues and in the soil where there is suffi¬ 
cient organic matter to furnish food. Sclerotia kept in a dry condition 
for nine months germinated readily when placed under proper conditions 
of moisture and temperature. On May 28, 1920, sclerotia of the fungus 
were placed in small vials with cheesecloth over the top and immersed 
in water in the laboratory and in the field where rice was irrigated. On 
September 10 these sclerotia were almost 100 per cent viable. They were 
still viable on November 4. Under field conditions where the disease 
occurred the fungus lived through the period of irrigation and started 
developing on the roots and stems of plants after the fields were drained. 
DISSEMINATION 
The sclerotia float on the surface of water like cork and may be carried 
easily by irrigation water. The fungus also grows vigorously as a sapro¬ 
phyte and may be carried about on old rice straw or in hay or other 
plant material that is moved from fields where it occurs. 
control measures 
Thorough cultivation hastens the decay of organic matter in the soil 
and also favors the germination of the sclerotia of the fungus. If in¬ 
fested soil is plowed early, allowed to stand for a few weeks, and then 
disked or well harrowed before seeding, the organic matter will have a 
chance to decay and the fungus will be more or less exhausted. Rice 
sown later than the average germinates readily and grows vigorously, 
thus giving the fungus less chance for attacking it. This is especially 
true where the soil is well prepared and a good seed bed is made. Seed 
sown before the soil has become thoroughly warm does not germinate 
promptly, and the growth of the seedlings is slow. Seedlings in such a 
