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2 BULLETIN 1116, U. S. DEPARTMENT OF AGRICULTURE. 
means of prevention extremely desirable. Some work was started 
by the Office of Cereal Investigations in the spring of 1919 at Crowley, 
La., in cooperation with the Louisiana Agricultural Experiment } 
Station. These investigations were continued for two years, but | 
were given only minor attention because a number of other diseases — 
were considered more important at the time. However, some results | 
were obtained which are thought to be of value, especially to those — 
who may undertake further investigation of these problems, | 
The investigations reported herein were undertaken with the hope ~ 
of clearing up the cause of the leaf-spot and seedling blight and, if — 
possible, to find some means of prevention. During the short period 
of these studies the writer’s attention was drawn to what appears to ) 
be the more important phase of this problem, namely, the staining ~ 
and decay of rice in shock and storage. The nature of the market- — 
able product is such that a very small percentage of stain or decay is 
reflected very decidedly in the grade. As previously mentioned, Van 
der Wolk states that 0.3 per cent is sufficient to cause rejection in the 
Kuropean markets. 
FACTORS FAVORING THE DEVELOPMENT OF THIS DISEASE. 
If the harvest season is wet and the rice remains in the fields, espe- 
cially in shock where it does not dry out, stack-burn is likely to develop. 
Such rice generally is found of poor quality when milled. This stain- 
ing of the grain is masked to a certain extent by polishing, but this 
is only temporary, as the polish gradually disappears and the decay 
continues to develop. If the rice is stored in a damp place after mill- 
ing or if not thoroughly dry before storing, it is subject to this type 
of injury. Repolishing is resorted to at times by millers to mask the 
discolorations in the rice. This would be more effective if the stains 
were superficial and were not subject to further development. Rice 
with slight infections of this type when shipped in damp, warm cars 
or bottoms for considerable distances, or when allowed to stand for 
many days under such conditions, may reach its destination with 
sufficient injury to cause it to be rejected. If not rejected, it would 
be given an inferior grade on the market. Small flecks, which might 
escape the observation of the most critical observer, are capable of 
spreading and destroying the entire kernel when the grain is placed 
in a warm, damp place. The exact degree of moisture required to 
cause these stains to develop is not known, but the humid atmosphere 
of the southern rice sections is known to favor this trouble. High 
temperatures, which are also common in the South, favor the develop- 
ment of these stains. If the rice is stacked damp or is allowed to 
go through a sweat after stacking it is likely to become stained if 
the temperatures remain sufficiently high for a few days, 


