DISEASES OV PLANTS. 881 



of tliH plant is the means of distrilmtion of tlie trouble, and examination showed the 

 presence of oxidizing ferments in the branches and cortex. Upon testing a number 

 of diseased specimens the oxidase was found present in a soluble condition in all the 

 diseased material but not in healthy trees. The conclusion is rea(;hed that the infec- 

 tion takes place below the ground, and whether other species of Stereum are capable 

 of causing the disease is to be a subject of future investigation. 



The olive knot in California, J. Isaac ( California Bd. Ilort. Rpt. 1901-.\ pp. 

 66-76, figs. 3). — The olive knot is said to be one of the most serious diseases of the 

 olive tree, and although long known in Europe it did not make its appearance in 

 ('alifornia until 1893. The outbreak of disease noticed at this time was checked by 

 the rooting out and burning of all diseased trees, and the disease was believed to be 

 under control when a second and more serious outbreak was reported early in 1901. 

 The disease, which is of bacterial nature and is due to Bacillus olae, is described 

 at considerable length, frequent (juotations being drawn from Italian and other 

 investigators regarding the nature of the disease and its remedies. At present the 

 olive knot is confined to a comparatively limited area and does not appear to be 

 spreading, the diseased trees l)eing destroyed as soon as observed. This method of 

 treatment is believed to be the most efficient remedy. No varieties seem to be 

 innnune, although the Mission olive appears more resistant than any other. What- 

 ever stimulates the growth of the tree appears to favor the spread of the disease, 

 and where irrigation is practiced the appearance of disease can be controlled to a 

 considerable extent by withholding water. 



The fumagin of olives, E. Zacharewicz {Prog. Agr. ct VH. {Ed. IJ Eat) , 24 {1903), 

 No. 4, pp. 110-113).— A- description is given of the fumagin, as well as of a second 

 disease caused by the fungus Cycloconium oleaginum, which may be recognized by 

 the presence on the leaves of black splotches which gradually spread, their centers 

 and borders being differently marked. The infested leaves after a time turn yellow 

 and fall from the trees. For the prevention of the attacks of these fungi the author 

 reconmiends spraying the trees with a mixture composed of soap 1 Rg., kerosene 

 4 liters, copper sulphate 1 kg., and water 100 liters. This should be sprayed over 

 the trees, the first application about the middle of April to be followed by the second 

 in a month or six weeks. In addition to describing these diseases, the author gives 

 suggestions regarding the cultivation of the olive and the handling of its products. 



Concerning the gooseberry mildew, P. Magnus {Separate from Gartevfiora, 51 

 {1902), pp. 3; abs. in Cenibl. Bakt. ii. Par., 2. Abt., 9 {1902), No. 19, p. 729).— A. 

 discussion is given of the distribution of Spluerotheca mors uvx. The author takes 

 exception to the statement of others that this mildew is identical with S. tomentosa, 

 which occurs on various species of Euphorbia. The mildews of the Euphorbia are 

 said to be quite common throughout Germany in regions where the gooseberry mil- 

 dew has never been known. 



The gooseberry mildew in Russia, P. Hennings {Ztschr. Pjlanzenkrank., 12 

 {1902), Nil. 1-2, pp. 16, 17). — The occurrence of the gooseberry mildew {Sphurotheca 

 morn uv:v) in different localities has led to a more extensive study of its distribution, 

 and it is reported as occurring in different parts of Russia. The author believes that 

 it is in all probability endemic to that country. 



Oidium and early pruning, G. Darragon {Prog. Agr. et Vit. {Ed. V Est), 24 

 {1903), No. 4, pp. 121, 122). — Notes are given on the effect of early pruning for the 

 prevention of powdery mildew. Vineyards that were pruned early in the winter 

 and sprayed during the summer did not suffer from attacks of mildew, but those 

 pruned late, even though freijuently sprayed, were more or less subject to injury. 



Report on a trip to Jamaica, F. S. PLvrle {Jour. New York Bot. flard., 4 {1903), 

 No. 37, pp. 1-10). — At the request of the director of the Jamaica Public Gardens the 

 author made a visit to that island and i)resents some brief preliminary notes on a 

 number of diseases of economic importance. Among the diseases noted are logwood 



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