DISEASES OF PLANTS. 55 



A preliminary note on the cause of flax-sick soil, H. L. Bolley {Proc. Soc. 

 Prom. Agr. ScL 1901, pp. 42-46). — A preliminary report is given on the cause of a 

 disease of flax which is designated as flax sickness. This disease manifests itself 

 after a few years of continuous cropping to flax, the soil being said to become flax 

 sick. Investigations of the soil show that there has been no exhaustion of soil fer- 

 tility, and further investigations have shown that it is due to the development of a 

 soil fungus, Fumrium lini. The behavior of the fungus toward the host is briefly 

 described, and the details of the life history of the parasite are to be published in a 

 future station bulletin. 



Flax wilt and flax-sick soil, H. L. Bolley {North Dakota Sta. Bui. SO, pp. 21-60, 

 figi^. 18). — A preliminary account of the flax wilt is given above. In the present 

 bulletin the author reviews the distribution of this disease and the various theories 

 as to its cause. At present it is reported from a dozen or more localities in North 

 Dakota, as well as from adjacent States. The appearance and characteristics of 

 the disease are described, from which it appears that plants are attacked at all 

 ages and die early or late according to the time and intensity of the attack. Young 

 plants wilt suddenly and soon decay if the weather Ijecomes moist, while older ones 

 which have become woody take on a sickly yellowish appearance, wilt at the top, 

 and slowly die. An examination of the roots shows that the smaller branches are 

 dead, as well as the lower part of the tap root. The diseased roots have a character- 

 istic ashen-gray color, and many of the mature plants show the dead gray tissue 

 only on one side of the tap root. 



A series of experiments is reported showing that soils infested by the fungus have 

 not lost their fertility, nor accumulated chemical substances which are detrimental 

 to the flax, as has been frequently claimed. As previously stated, the cause of this 

 disease is a fungus jjarasite, to which the name Fusarium lini is given. The life his- 

 tory of the fungus so far as known is described, and it is said that while living nor- 

 mally as a saprophyte it attacks the flax through the young tissues of the seed, 

 leaves, stem, or roots. The means of spreading the disease were investigated, and it 

 was lound that it can be readily introduced by particles of soil, dirty implements, 

 through seed, etc. 



Experiments were conducted to ascertain means for seed treatment, from which it 

 was found that the seed could be advantageously treated with a formalin solution of 

 1 part to 330 parts of water. A number of other chemicals were tested, and among 

 them copper sulphate and corrosive sublimate proved effective, but possessed no 

 advantage over the formaldehyde treatment. 



In treating flaxseed the author calls attention to the necessity for having the seed 

 thoroughly cleaned before treatment, and applying the solution evenly and only 

 enough to dampen the surface of the seeds, after which they should be thoroughly 

 stirred and dried immediately. From the author's investigations there seems to be 

 little possibility of finding any substance which would destroy the fungus in the soil 

 without injuring the germinating crop. On this account crop rotation seems to offer 

 the best solution of soil treatment. 



Potato diseases and their remedies, L. R. Jones and A. W. Edson ( Vermont 

 Sta. Rpt. 1901, pp. 227-235). — The authors report on experiments for the control of 

 potato blights as they occurred in 1900, and potato-scab experiments of 1901. The 

 summer of 1900 is said to have been unfavorable to the development of the fungus. 

 There was a considerable amount of early blight, but the late blight and dry rot were 

 almost entirely absent from the station fields. This is attributed to the use of clean 

 seed and spraying. In the spraying experiments the efficiency of several fungicides 

 and their use at different dates was tested. Standard Bordeaux mixture and 2 trade 

 compounds, known as Boxal and Bodo, were tested. The Bordeaux mixture to 

 which Paris green was added gave the l)est results. Rows of potatoes which were 

 sprayed twice with this mixture yielded at the rate of 285 bu., and gave an increase 



5301— No. 1—02 5 



