10 
BULLETIN 1120, U. S. DEPARTMENT OF AGRICULTURE. 
explains why no canker occurred in those portions of the rows of 
young flax plants shaded by the vertical strips of canvas, while at 
the same time some plants were cankered in the portions of the rows 
not so shaded. 
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Fig. 2.— Diagram showing the variations In soil-surface temperatures in 
different parts of plat C at Fargo, N. Dak., on July 18, 1919. 
Table 7 also shows that higher soil-surface temperatures occurred 
where the heavy dark soil had not received a surface application of 
li'ght yellow sand. This probably explains why more canker occurred 
in the portions of the plats where sand had not been applied, as 
shown by the data in Tables 2 and 3. 
' On July 18, 1919, when the soil-surface temperature data shown 
in Table 7 were taken, the sun shone brightly until 2.30 p. m., when 
it became obscured by clouds. About 4 o'clock it began to rain. 
Previous to this the soil was fairly dry. 
