HEAT CA:InKER OF FLAX. 



Table 2 shows that under three different conditions of shade more 

 canker occurred on the heavy dark soil than on the same type of 

 soil which had been covered with yellow sand a quarter of an inch 

 in depth. It also shows that canker occurred most abundantly 

 where the soil was shaded the least. This holds true in general 

 both where sand was applied and where it was not used. 



As already stated, no canker occurred on the later sowings in 

 plats B and D, and only a limited occurrence was noted in plat C^ 

 sown on June 27, where the canvas shades were placed, as shown in 

 Figure 1. The data obtained from this plat, taken when the plants 

 were about 4 inches high, are summarized in Table 3. 



Table 3. — Number offia:c plants cankered under various conditions in plat C, at Fargo. 

 N. Dak., sown on June 27, 1919. 



[Data on the oeciirrence of heat canker of flax recorded on July 18, 1919.] 



Row. 



Shaded by canvas. 



Not shaded. 



Row. 



Shaded by grain. 



On sand. 



No sand. 



On sand. 



No sand. 



On sand. No sand. 



No. 1 















1 





 2 

 2 

 

 

 

 



3 

 4 



23 

 2 



10 

 3 

 2 

 

 

 1 



No. 11 



i 0' 



No. 2 











No. 12 



No. 13... 



i 0' 



No. 3.. . . 



a 



No. 4 







No. 14 



1 



No. 5 







No. 15 







No. 6 







No. 16 







No. 7 





No. 17 



No. 18 







No. 8 









No 9 



1 





No. 10 









i 





It is evident from Table 3 that flax plants grown behind the 

 canvas shades were not cankered, while some plants were cankered 

 in the same rows when not shaded by the canvas, especially where 

 sand was not applied. No flax was cankered where nurse crops 

 were used. The row having the most cankered plants (No. 3) was 

 the one sown thinly (at half rate) and double spaced from the next 

 row on the south. While less canker occurred in this experiment, 

 the results are in line with those obtained from plat A, presented 

 in Table 2, in that the flax was cankered most where the soil was 

 shaded least and where no sand was applied. 



Experiments similar to those of 1919 were conducted during 1920, 

 except that sand was omitted. A single variety resistant to flax 

 wilt was used, and more variation was made in the rates of seeding. 

 Six experimental plats were sown during the season at intervals of 

 approximately two weeks. Canker appeared to a greater or less 

 degree in the last four sowings. Plants emerging on May 28 or 

 earlier were not cankered. The injury of plants in the plats where 

 canker appeared occurred from 4 to 14 days after emergence. The 

 data presented in Tables 4, 5, and 6 were obtained from the two 

 plats in which cankered plants appeared in the greatest numbers. 



