1916] DISEASES OP PLANTS. 653 



Potato disease, Korff {Prakt. Bl. Pflanzenhau u. Schutz, n. ser., IS {1915), 

 No. S, pp. 109-111, fia-t. 2). — Brief reference is made to a leaflet issued by the 

 Institute for Agricultural Botany at Munich, dealing with leaf diseiise and 

 Phytophthora tuber rot of potato and the control of both these troubles by the 

 timely use of copper sprays. 



Marasmius on sugar cane, J. R. Johnston {Myeologia, 8 (1916), No. 2, p. 

 115). — Referring to the description given by Fulton (E. S, R., 19, p. 956) of the 

 fungus designated by him as M. plicatus, causing root disease of sugar cane in 

 Louisiana, the author states that his own specimens on sugar cane from 

 Louisiana and Texas answer rather to the description of M. stenophyUus (.^f. 

 ifenuustis), said to have been reported on bananas in many West Indian islands 

 but not before on sugar cane. 



Effect of colored light on the mosaic disease of tobacco, G. H. Chapman 

 {Science, n. ser., 43 {1916), No. 1111, pp. 537, 538).— The author reports some 

 investigations conducted to verify the conclusions of Lodewijks (E. S. R., 24, 

 p. 648) that blue light offers a cure for the mosaic disease of plants. 



The diseased leaves of a number of tobacco plants were covered with hoods 

 composed of different colored cloth, and it was found that when blue light was 

 used there was a suppression of tlie leaf color variation more or less permanent 

 in character. With a single exception, the treated plants showed no typical 

 symptoms of the disease for at least two weeks after the removal of the hoods. 

 That the disease was, however, not controlled was shown by the inoculation of 

 healthy plants with the juice of the treated plants, as this produced the disease 

 in nearly every case. This is taken to show that the active principle of the 

 disease is present in the apparently normal, fully recovered leaves and that it 

 is highly infectious. 



The leaf spot disease of tomato, E. Levin {Michigan Sta. Tech. Bui. 25 

 {1916), pp. 5-51, pis. 9, figs. 2). — This bulletin gives the results of experiments 

 on the leaf spot disease of tomato, due to Septoria lycopersici, and recom- 

 mendations for its control. While many investigators have reported this fungus 

 as causing the leaf spot disease of tomato, its parasitism was definitely proved 

 by the author's investigations. The morphological, ecological, and physio- 

 logical relations of the organism are described at some length, and control 

 measures, which include the planting of clean seedlings in clean soil and 

 thorough spraying with Bordeaux mixture, are recommended. 



A canker of apple caused by Plenodomus fuscomaculans, G. H. Coons 

 {Abs. in Science, n. ser., 43 {1916), No. 1106, p. 364)- — A serious canker of apple 

 is said to occur in some orchards in northern Michigan. The canker is char- 

 acterized by elongated lesions which are commonly accompanied by a checking 

 of the bark into small squares or rectangles. The lesions are said to extend 

 along the limb, commonly on the underside. In the older cankers the killed 

 bark drops off, leaving the bare wood. 



The causal relation of the associated organism has been shown by inocula- 

 tion experiments, and the results of a study of its physiological relations have 

 been previously noted (E. S. R., 34, p. 647). Successful inoculations were ob- 

 tained on the limbs of Wealthy, Duchess, Jonathan, and Ben Davis apples, as 

 well as on the Hyslop crab. Other standard varieties seem more resistant. 

 The fungus has also been successfully inoculated into pear, small cankers hav- 

 ing been formed, but no inoculations have succeeded on apple leaves. 



The disease, it is claimed, may be successfully controlled by the means 

 commonly advised for apple canker. 



Fuxigi producing the heart rot of the apple, B. O. Dodge {Myeologia, 8 

 {1916), No. 1, pp. 5-15, pis. 4; abs. in Science, n. ser., 43 {1916), No. 1106, p. 

 S66). — Living apple trees at Litchfield, Conn., are reported as being infected 



