DISEASES OF PLANTS. 1087 



A gum-forming- bacterium, from Eucalyptus stuartiana, R. G. Smith {Proc. 

 Linn. S(jr. Xew Sml/i Wn/rs, J7 {H'OJ), pt. J, pp. 2.)0-?3G, pJ. 7). —A description is 

 given of Bacterium eucali/pfi, n. sp., which is found in the sacchariu exudate of 

 Eucalyptus .'ituartiana. The occurrence of this organism has been ])reviously men- 

 tioned (E. S. E., 14, p. 876). 



The bacterial origin of gums of the arabin group, K. G. Smith {Proc. Linn. 

 Soc. New South Wale.% 21 {1902), pt. .*', pp. 383-407). — A study was made of various 

 gums to determine the possibility of their bacterial origin. Fresh material was 

 obtained from Acacia perinimrvis, and from the twigs of this tree small portions of 

 gum were removed, the exterior portion sterilized, and cultures made from the frag- 

 ment:^. In nearly every case 2 forms of bacteria were found present. The first, to 

 whicii the name Bacteriiuii acacix is given, the author believes is the cause of the 

 l)roduction of the principal portion of the gum found on this plant. This organism 

 in the laboratory was found to form a gum whicli l)ehaved in all its reactions the 

 same as the natural gum. The formation of gum on this tree is considered a bacterial 

 disease, the bacteria elaborating the i)lant juices into gum wliich resembles the gum 

 arable in its properties. 



The second organism, to wliicii tlie name B. metarabinum is given, is believed to 

 produce the more insoluble gums whicli occur associated with the others. In con- 

 clusion the author states that gums of the arabin group occur not only in the Acacias, 

 but among other plants, particularly certain Rosaceae, and he believes it probable 

 that they are produced by the worii of similar organisms to those described above. 



Cucumber diseases, G. E. Stone {Mas.%ichusetts Sta. Bui. 87, pp. 29-43, figs. 8). — 

 Descriptions are given of a number of cucumber diseases, particular attention being 

 paid to those occurring on cucundiers grown under glass. Among those described 

 are a leaf curl, in which the leaves assume a spherical form due to the inrolling of 

 the wilted edges of the leaves; a stem curl, which is said to be a more pronounced 

 form of the same disease; and a cucumber wilt, all of which are attributed to improper 

 conditions of cultivation. Among the diseases caused by fungi are the anthracnose, 

 downy mildew, timl:»er rot, damping off, powdery mildew, nematode diseases, etc. 

 These different diseases are described and preventive means suggested where such 

 aie known. The author recommends tlie fumigation of the houses before planting 

 witli sulphur or potassium cyanid. The sulphur treatment is less expensive, but for 

 most purposes the cyanid is to be preferred. Either of the treatments will remove 

 some of the more common pests of greenhouses, and it is believed that growers will 

 find the practice of fumigation highly advantageous. 



Orchard diseases and their remedies, L. R. Jones and W. J. Morse ( Vermont 

 Sta. Rpf. 1902, pp. ,?50-^.55).— A description is given of the destructive presence of 

 the apple scab fungus during the summer of 1902. Owing to the excessive amount 

 of rainfall spraying was much interfered with, and in many cases wdiere applications 

 of Bordeaux mixture and Paris green were made early in June a rusting or russeting 

 of the fruit was reported and in a few cases there was a decided spotting of the foli- 

 age. Similar troubles were reported during the season from a number of localities, 

 and after a careful examination the authors reached the conclusion that the trouble 

 is due primarily to weather conditions and is aggravated by the spraying. An 

 inspection of the orchards of Grand Isle gave abundant evidence of gain from spraying, 

 and while there was a serious amount of damage due to the russeting the quality of 

 the well-sprayed fruit was much higher than that from the unsprayed. The experi- 

 ence derived during the season suggests that the strength of solutions should be 

 varied to suit the period of growth, climatic conditions, and fineness of the spray. 

 The coarser the spray the weaker should be the solutions, and in early spring 

 stronger mixtures may be used than during the summer. 



Studies are reported upon plum blight which have already been noted (E. S. K., 

 14, p. 880). 



