Minnesota Plant Diseases. 311 



count is taken from a bulletin of the North Dakota Ag. Ex. Sta. 

 by H. L. Bolley, who first discovered the true cause of the dis- 

 ease. 



"The plants are attacked at all ages and die early or late in 

 the stage of growth according to the time and intensity of the 

 attack. If the soil is much afifected, that is to say "flax sick," 

 most of the plants are killed before they get through the surface 

 of the ground. Such areas appear m a field of flax as centers 

 of disease, which enlarge throughout the summer as new plants 

 sicken, wilt, and die down around the margins of the spots, 

 finally giving the whole field a spotted appearance. Young 

 plants two to five inches in height wilt suddenly, dry up, and 

 soon decay if the weather becomes moist. Older plants which 

 are quite woody take on a sickly, weak, yellowish appearance, 

 wilt at the top, slowly die, turn brown, and dry up. Nearly 

 mature plants which are attacked, but not yet dead, are easily 

 pulled up, the roots breaking off easily at about the level of 

 the furrow slice." 



Fig. 156. — Flax wilt. Wilted seedlings. After Bolley. 



"Upon examination, most of the smaller branch roots are 

 found to be dead, as well as the tap root below the point at 

 which it breaks off. These dead roots and the parts of the tap 

 root already diseased have a very characteristic ashen gray 

 color. Many nearly mature plants, which are attacked late in 

 life, show this dead gray down one side of the tap root only. 

 The leaves, side branches, and a strip of the main stem above 

 this portion are dead, giving a peculiar one-sided blighting, 

 similar to the appearance of a tree struck by lightning." 



"If the disease is sowed with the seed upon breaking, but a 

 few of the plants are attacked the first year; and, at flowering 

 time, dead plants will be seen to be quite evenly distributed in 



