FUNGI IMPERFECTI 



319 



XXIII. FLAX WILT 

 Pusarium Lini Bolley 



BOLLEY, H. L. Flax Wilt and Flax Sick Soil. N. D. Agl. Exp. Sta. Built. 

 50: 27-60. 



This important flax disease, which is reported as particularly 

 destructive in North Dakota, seems to be characterized by symp- 

 toms similar to many other diseases caused by species of Fusa- 

 rium. Affected plants may be killed in the seedling stage, or 

 they may wilt and die at any time during the growing period. 



The fungus has been found to be ordinarily very abundant in 

 soils in which flax has been grown several successive years, and 

 it is considered to be the 

 chief cause of the failure 

 of flax upon land where 

 flax has previously been 

 grown. In fact, Bolley 

 points to this fungus as 

 the cause of flax-sick soil. 

 It would seem to be doubt- 

 ful, however, if the action 

 of this fungus would ex- 

 plain all the peculiar rela- 

 tions of flax to the soil 

 upon which it has been 

 grown. The fungus pro- 

 duces an abundance of conidia which are typically somewhat 

 curved, 4-celled, and prompt to germinate. No perfect stage of 

 this organism has been found. It is believed that the old straw, 

 stubble, etc., of diseased stalks harbor the fungus, and that since 

 the fungus is in nature, perhaps, more particularly a saprophyte, 

 there is ordinarily abundant opportunity for^ it to be carried over 

 from one year to the next. 



Control. Control consists of seed treatment ; yet in this con- 

 nection it should be said that the seed of flax are very readily 

 injured by treatment even with water, and therefore much caution 

 is needed to prevent injury to the seed. It is advised to sprinkle 

 the seed with a formalin solution, using formalin at the rate of 



FIG. 151. CHINA ASTERS DWARFED AND 

 KILLED BY FUSARIUM 



