DISEASES OF PLANTS. 477 



DISEASES OF PLANTS. 



Some bacterial diseases of plants prevalent in Ontario, F. C. Harrison and 

 B. Barlow (Ontario Ayr. Col. and Expt. Farm Bui. 136, j>j>. 20, figs. 12). — An account 

 is given of the fire or twig blight due to Bacillus amylovorus, a bacterial disease of 

 beans due to Pseudomonas phaseoli, a soft rot of white turnips, cauliflowers, and cab- 

 bages, a rot of Swedish or yellow turnips, and a harterial rot of stored celery. 



The fire or t w jlt blight, which affects pear and apple orchards, is described at con- 

 siderable length, and notes given on the distribution of the disease, losses attributed 

 to it, symptoms of the disease, life history of the organism causing it, and suggestions 

 for its prevention. 



The bacterial disease of beans described affects the wax beans grow n largely for 

 canning purposes. The disease begins at the margin of the leaf, or where it has been 

 injured by insects, winds, or hail, and gradually a yellow spot appears, which spreads 

 slowly, the diseased tissues finally becoming brown and almost Mark. Inoculation 

 experiments have shown that the cause of this trouble is the organism Pseudomonas 

 phaseoli; and for its prevention it is recommended that healthy seeds be used in 

 planting, to be treated as a precautionary measure with water heated to 122° V. for 

 LO minutes, or soaked for a short time in a corrosive sublimate solution, 1 partto 1,000 

 of water. When the disease has made itself apparent the cultivation of beans in that 

 soil should he abandoned for several years, as the organism is believed to be able to 

 remain in the soil for some time. 



The soft rot of white turnips, cauliflowers, cabbages, etc., is attributed to the 

 organism Bacillus oleracese. This organism produces in these plants a sof rot which 

 causes considerable loss in the fields. A more extended account of this disease is 

 given elsewhere (see p. 480). 



The soft rot of Swedish or yellow turnips is caused by an organism quite similar to 

 the one causing the soft rot of white turnips, but is subject to slightly different condi- 

 tions. For the prevention of this disease it is recommended that the roots be thor- 

 oughly ripened and cured before being placed in storage, in order to secure this 

 result the harvesting of the root crop should be delayed as long as possible, and after 

 pulling the roots they should be allowed to dry before being stored. 



A brief description is given of a rot of stored celery which was observed at the 

 agricultural college during the winter of 1903-4. From a number of the decayed 

 stems cultures were made and 2 varieties of Pseudomonas fluorescens were isolated. 

 One variety causes the steins to become brownish or amber colored in rotting, while 

 the other shows a greenishdjlue color. Fresh celery plants inoculated with the 

 organism after a few days showed the presence of the rot, indicating that these 

 organisms were its cause. As precautionary measures for preventing the rot the 

 authors recommend that celery should be packed with the roots in clean soil, which 

 should be kept moist but not wet, and the atmosphere of the soil or storage room 

 should be kept at a uniformly low temperature, but little above the freezing point. 



Investigations at the station of plant pathology, G. Delacroix (Bui. Soc. 

 Mycol. France, 19 (1903), Xos. 2, pp. U8-14- r >; •/', pp. 342-355 |.— Notes are given on a 

 number of investigations carried on at the laboratory under the direction of the 

 author. Among them are discussed the conidial form of the black-rot fungus, an 

 apple-tree canker due to Sphseropsis malorum^ a monstrous form of ergot, a disease of 

 •ruavas caused by Glaosporiumpsidii, n. sp., a mildew-like diseaseof mulberries caused 

 by Ovulariopsia ulmorica, n. sp., and the parasitism of Dolhichiza populea on several 

 species of poplars. 



Letters on diseases of plants, X. A. Cobb (Dept. Ayr. New Smith Wales, Misc. 

 Pub. 666, 2. ser., pp. /•>'.;, pis. 11,, figs. 132). — This is a compilation, with additions and 

 emendations, of papers by the author on this subject, which were published from 

 time to time in the Agricultural Gazette of New South Wales. 

 15014— No, 5—05 5 



