DISEASES OF PLANTS. 849 



or acitl producer, i. e., not facultative anaerobic. Forms 'cavities around the bun- 

 dles, but seems to be only feebly destructive to cellulose. Produces a brown pigment 

 in the host plants and on steamed cruciferous substrata, especially the turnip. 

 Grows very rapidly on steamed potato cylinders at room temperatures but without 

 odor or the formation of any brown pigment. Liquefies gelatin. Grows well at 17 

 to 26° C, and is killed by 10 minutes' exposure to 51° C. Organism closely related to 

 Wakker's Bacterium hyacinthi, from which it differs chiefly in its pathogenic proper- 

 ties, its duller yellow color, and its higher thermal death point." 



The black rot of the cabbage, E. F. Smith (U. 8. Dept. Ayr., 

 Farmers' Bui. 68, pp. 22, fig. 1). — The author gives a popular bulletin on 

 the black rot of cabbage, which is of bacterial origin, due to Pseudo- 

 monas campestris. Technical descriptions of this disease have been 

 previously given. 1 The disease in cabbage is characterized by the 

 dwarfing or one-sided growth of heads or, if the disease is very severe 

 and began early in the season, by the entire absence of heads and, in 

 extreme cases, by the death of the plant. If the stumps of affected 

 plants are broken or cut across, a brown or black ring will be observed 

 corresponding to the woody part of the stem, this being the part of 

 the plant subject to disease. 



The cause of the disease, as has already been stated, is bacterial, the 

 germ entering the plant above ground and usually at the margin of 

 the leaves through the water pores. It is not confined to cabbage, but 

 attacks a number of other plants belonging to the mustard family. 

 The common charlock or wild mustard is very subject to the disease 

 and may be the means of causing its spread. 



An account is given of field studies made in 1897, together with its 

 geographical distribution. At present it is known to occur in Alabama, 

 Kentucky, Iowa, Nebraska, Illinois, Indiana, Ohio, Minnesota, Wiscon- 

 sin, Michigan, New York, Pennsylvania, New Jersey, Maryland, Vir- 

 ginia, and possibly Florida. The different methods of introduction and 

 transmission are discussed, as well as the susceptibility of different 

 varieties. Indications seem to show that the parasite lives over win- 

 ter in the soil. 



Suggestions for the prevention of disease are given, the principal of 

 which briefly summarized are to plant the cabbage seed in a, seed bed 

 where the disease has never occurred and set plants on land which has 

 not been in cabbage or other cruciferous plants for some years. As a 

 matter of precaution, the use of stable manures should be avoided, 

 since they may possibly serve as a means of conveying the germs to 

 uninfected fields. Infection must be guarded against from tools used 

 on infected lands or allowing stock to pasture over the different fields. 

 The cabbage butterfly and harlequin cabbage bug must be constantly 

 kept in subjection, as it is probable that they are very efficient means 

 in spreading the disease. As a palliative remedy all diseased plants 

 should be removed as quickly as they appear, and weeds, especially 



1 Iowa Sta. Bui. 27 (E. S. R., 6, p. 998) ; Centbl. Bakt. u. Par., 2. Abt., 3 (1897), No. 

 11-12, p. 284 (see above). 



