10 BULLETIN 1116, U. S. DEPARTMENT OF AGRICULTURE. 
controls. The sclerotial fungus seemed to be hardest to kill in Hon- 
duras rice. 
The Japanese writers were treating for the control of Helmintho- — 
sporium. They recommended presoaking overnight and soaking 
with hot water at 54° C. for 5 minutes or at 52° for 10 minutes. They 
found that the hot-water treatment did not control Piricularia. This 
was no doubt due to other sources of infection in the field. The hot- 
water treatment did not prevent the black sclerotial leaf-spot in 
Louisiana. Treated seed, untreated seed,-and clean Honduras seed 
from California produced plants which were equally diseased. The 
fungus doubtless lives over in the soil and on old rice straw and infects 
the rice plants the following season. There are strong indications 
that this fungus produces conidia which cause the leaf infection. 
However, this has not been proved definitely. It seems hardly 
possible that all of the abundant infection which occurs could be 
caused by sclerotia. 
CONCLUSIONS. 
The results given in Tables 3 and 4 show that the hot-water treat- 
ment will kill the fungi carried within the rice seed and not injure the 
viability of the seed if the proper methods are used. It also indicates 
that these fungi have a tendency to lower the vitality of the seed, as 
is shown by the better germination of seed grown in California, which 
were relatively free internally from fungi. Hot water does not elimi- 
nate this difference but does prevent further development of the fungi 
in the seed, provided the seed is sown in clean soil where there is no 
subsequent infection. 
Until more information is obtained regarding these fungi and their 
life histories it would be inadvisable to recommend seed treatment 
which would kill only the fungi in the seed. Where infested seed is to 
be sown on virgin soil or soil where rice has not been grown previously,. 
it may be advisable to treat the seed to prevent introducing these 
fungi into the new lands. Seed from California would be good for | 
this purpose without treating were it not for the numerous weed seeds 
that might be introduced in this way. The matter of soil infestation 
by the various fungi concerned has not been investigated sufficiently 
to show what part it might play in seed decay and seedling blight. 
From a commercial standpoint, some form of treatment should be 
profitable where rice is to be stored or shipped under warm, moist 
conditions. The hot-water treatment would be too tedious and 
expensive for treating the commercial product. It is hoped that 
through future investigations some practicable form of treatment will 
be discovered. A process of drying under temperatures that would 
kill the fungi and not injure the texture of the grain might be possible. 
Van der Wolk’? recommended the thorough drying of rice and dry 
—$<—<—$———— 

7Wolk, P.C. van der. Op. cit. 

