HEAT CAZSTKER OF FLAX. 



11 



The temperature records for the seasons of 1920 and 1921 (Table 

 8 and Figs. 3 and 4) were taken with a soil thermograph the bulb 



n 



J'O'A/E 



. _ . . ^ ^ ^ - , ^ o(^rNCM cv vAj ,->( tq (\; c^^n,I<)-vcl»5l^lo^e>N(^)Oi5 



E 





Fio. 3. — Diagram showing the daily maximum soil temperatures at a depth of half an inch, as re- 

 corded by a soil thermograph with bulb barely covered, at Fargo, N. Dak., during June and July, 

 1920 (see Table 8). The black diamonds show times when severe canker occurred and the wMto 

 diamonds times when canker was slight. 



JiJA/E 



juty 



.o<'o>i-io.os.D°>-'j^sit;^^i?!;^^^^Si?^'o;'^!^^;^^gxM'o»iov>s^»s^sig!t!Qigi^^^^i^sissi!;s^?;?SN§; 



Fig. 4. — Diagram shov ing the daily maximum soil temperatures at a depth of half an inch, as re- 

 corded by a soil thermograph with bulb barely covered, at Fargo, N. Dak., during June and July, 

 1921 (see Table 8). 



of which was buried in the surface inch of soil. No plants were 

 allowed to grow within 4 feet of the bulb. This thermograph re- 

 corded the soil temperature at a depth of approximately half an inch. 



