652 SUMMARY OF CURRENT RESEARCHES RELATING TO 



authors within a few days of each other. The genera are identical. 

 Another case is the publication of Microdiplodia in 1901 in Rabenhorst's 

 Krypt. Flora, Fung. Imperfect. The same genus, under the same name, 

 was published by F. Tassi in 1902. The authors give also a list of 

 recently described new fungi which are identical with already well- 

 established species. 



Canker of Fruit Trees.*— Joseph Brzezinski has devoted much time 

 and attention to the disease known as canker, and almost universally 

 considered to be due to the ravages of a fungus Nectria ditissima. His 

 first experiments were conducted with a view to studying the effects of 

 the fungus, and, to induce canker, he infected young apple trees with 

 the spores of Nectria, with continued negative results. A closer 

 examination of the diseased parts of the trees revealed the constant 

 presence of Bacteria in the tissues. Cultures were made of these and 

 healthy trees inoculated, with the result that canker was easily produced 

 by the introduction of the microbes. The author gives a detailed account 

 of the organism, which he designates Bacterium Mali, and describes its 

 action on the tissues of the host plant. The wood parenchyma succumbs 

 easily to the action of the bacterium while the cells of the medullary rays 

 are more resistant. This is explained by the greater vitality of these 

 cells. 



General bacteriosis of the tree is a malady to which he also calls 

 attention, and which results in the death of the tree. Bacteria were 

 found in profusion in branches suffering from the malady. 



Nodosities on the roots, also a serious danger to the trees, were 

 examined and experimented on, and were found to be due to Bacterium 

 mali. Chlorosis of plants he also traces to bacterial action. 



On the pear he found cankers similarly produced. The Bacterium 

 was indistinguishable from that in the apple, but in artificial cultures it 

 formed yellow coloured colonies while those of the apple Bacterium were 

 always greyish-white. It was considered therefore to be another species, 

 and named B. Pyri. Still another, B. Coryli, was found to cause canker 

 in nut-trees. The author concludes that bacterial disease of trees is as 

 common as it is deadly. Gummosis, also due to bacteria, is accompanied 

 by a discharge of gum. There are thus two very different series of 

 vegetable pathogenic bacteria at work, those that form gum, and those, 

 as in the case of canker and chlorosis, that do not cause any exudation. 



Fungicides.f — R. J. Moss has tested the effect of various copper 

 solutions on potato-disease. He recommends for spraying the affected 

 plants, Burgundy mixture, a solution of copper sulphate with ordinary 

 crystallised sodium carbonate in the proportion of three parts of soda to 

 two of copper sulphate. The deposit produced on the leaves by this 

 mixture is very adhesive and resists the action of rain, and is thus more 

 effective as a remedy for potato-blight. 



T. Johnson % gives the results of experiments on smutted grain. 

 The object in this case is to destroy any fungus spore adhering to the 



* Bull, intern. Acad. Sci. Cracov., 1903, pp. 95-142 (7 pis.). 

 t Econ. Proc. Roy. Dubl. Soc, 1. (1902) pp. 109-18. 

 X Tom. cit., pp. 119-31. 



