FUNGOID PESTS OF CULTIVATED PLANTS 251 



FLAX WILT. 

 Fusarium Lini (Boll.), PI. XXIV. fig. 33. 



This disease has long been known in Holland, Belgium, and Northern 

 France. It exists also in Ireland and in Germany, but is hardly known in 

 Russia. When the soil is impregnated, after successive crops, and the 

 flax becomes " wilted," the land is said to be "Flax sick." 



The plants are attacked at all ages, and die early or late in the stage 

 of growth. If the soil is much infected, most of the plants are killed 

 before they get through the surface of the ground. Young plants two to 

 five inches high suddenly dry up and decay. Old plants which are quite 

 woody take on a sickly, weak, yellowish appearance, wilt at the top, slowly 

 die, turn brown, and dry up. 



The fungus which causes this disease was first detected by H. L. Bolley, 

 and called by him Fusarium Lini, and is thus described : Vegetative 

 hyphae light-coloured, septate, branching irregularly, ramifying the tissue 

 of the stems and roots of the host. Spore tnfts (sporodochia) erumpent, 

 compact, slightly raised, pale cream or flesh-coloured. Sporophores short 

 and closely branched, or conidia sometimes arising from wart-like pro- 

 tuberances upon a compact bed, or stroma. Conidia four-celled, fusiform, 

 slightly curved or falcate (27 x 3/t to 38 x 3^), living in the humus of 

 the soil, able to attack the Flax plant, and causing the disease. 



Living normally as a decay form (saprophyte), it can also invade the 

 living tissue of its host. It can live and increase upon the decaying 

 matter found in the soil, especially on old roots and stems of the Flax 

 plant, and can readily thrive there for a long period. It may remain in 

 the soil for more than four years, without the presence of a Flax crop. If 

 any of the filaments come in contact with a young Flax plant, they 

 penetrate at any point, through the seed, leaves, stem, or roots. When the 

 plant dies it becomes food material for the fungus. 



The results of experiments show that a rather strong solution of 

 formaldehyde, acting a short time, will work satisfactorily on Flax seed. 

 The proper strength to be used in sprinkling and shovelling methods is 

 about 1 part to 330 parts of water (approximately 1 pound to 40 gallons). 

 The seed should be spread on a tight floor and sprayed with a small 

 amount of the liquid, then raked over rapidly, until all the surfaces of the 

 seed are evenly moist and not wet enough to gum, but evenly damp ; then 

 continue to shovel the grain so as to get it dry as soon as possible. Avoid 

 any excess of moisture. 



Cease sowing Flax on the same land year after year. Put at least 

 one cultivated crop and two or more other crops between Flax crops. 

 Burn as much of the old Flax straw and stubble which remain upon the 

 ground as possible. Avoid the evil effects of deep planting. The Flax 

 disease does more injury to seedlings when the seed is placed deep in 

 loose soil than when planted shallow. One-half inch to three-fourths is 

 the best depth. 



Bolley, in. U.S.A. Agri. Exp. Sta. N. Dakota, Bull. 50, 1901 ; Journ. 

 R.H.S. vol. xxvii. p. 751. 



