74 Bacterial Diseases of Plants 



The "Mosaic Disease of Tomato" has also been shown to be trans- 

 missible through the soil and tlie same argument applies in this ease also. 



"Sprain" in potatoes is another of these obscure phenomena and 

 there would seem to be several different kinds of "sprain." One form has 

 been attributed (25), upon what evidence the author is unable to discover, 

 to an arrested condition of Winter-Rot. Another form which has been 

 described as "Internal Disease" by Horne(i7) is believed to be similar to 

 a disease which the writer is now investigating and which he has found 

 to be due to a bacterial parasite (33). 



"Silver-Leaf Disease" in plum has also been suggested as due to a 

 bacterial parasite (5) and Smolak(47) observed bacteria in the vessels of 

 the leaf although the relationship of these to the disease was not deter- 

 mined. 



The need for further investigation of bacterial diseases and for more 

 workers in the field is vital, how vital has recently been shown by the 

 discovery in America of two diseases of cereal crops, a bacterial blight of 

 Barley (21) and a disease of Wheat (4G); the latter is stated to be "not as 

 destructive as the rusts but more destructive than the smuts and very 

 likely more difficult to control." The means of control in bacterial 

 disease are very difficult and necessitate a vast amount of research. 

 Possible lines of attacking the problem have been so ably set out by 

 Smith (45) in his Conspectus of Bacterial Diseases that little can be added 

 in the present state of our knowledge. 



REFERENCES. 



An asterisk plnred before a reference denotes that the cultural and ph)/siologicaI 

 characters of the organis)n dealt loith are described in the paper. 



*(1) Appel, O. Untersuchungen liber die Swarzbeiiiigkeit und die durch Bakterien 

 hervorgeriifene Knollenfaule der Kartoffel. Arb. a. d. biol. Anst.f. Land- it. 

 Forstwirthschafl am Kais. Gesundheifsamt. Bd. lu, 1903, s. 364. 

 (2) Arb. Kats. Biol. Anst.f. Land- u. Forstwirthschaft, Bd. V, 1905-7. 



*(3) Barker, R. T. P. and Grove, O. A Bacterial Disease of Fruit Blossom. Ann. 

 App. Biol. vol. r, 1914, p. 85. 



(4) Barker, R. T. P. A Bacterial Disease of Gooseberiy. Ann. Rpt. Agric. and 



Hort. Research Sla. Long Ashton, Bristol, 1915, p. 97. 



(5) Blackmore, J. C. Annual Report N. Z. Dep. of Agric. 1909, p. 5.'?. 



(0) BoLLEV, H. L. Potato Scab: a bacterial Disease. Agr. Science, vol. iv, 1890. 

 pp. 243, 277. 



(7) Potato Scab and possibilities of its prevention. N. Dakota St((. Bull. 



1891. 



(8) Brooks, C. Blossom end Rot of Tomatoes. Phi/topal/,. vol. iv, 1914, p. 315. 



