DISEASES OF PLANTS. 569 



ings with potassium sulphid solution. All the dead leaves should l)e eolleeted and 

 liurned in the autunni and the ground under and around the bushes dug so as to bury 

 any stray spores which may be lying upon the ground. 



Leaf cast of pine, C. von Tubeup (Arh. K. ncsHiulheUscuidi', Biol. Aid., -2 [1901), 

 So. 1, ]>]). 1-160, pis. 7, figs. 32). — A review is given of the literature relating to this 

 disease, and the various theories as to its eause are discussed. Leaf cast is a very 

 troulilesome disease in nurseries where seedlings of Pbms siilceslrh are grown, not 

 infrei]uently ?ausing the complete destruction of all the young plants. The princi- 

 pal cause of the injury, according to the author, is to l)e attributed to Lojihodermluin 

 jiiiKisIri; and the systematic relationships, morphology, biology, and pathological 

 effect upon the host plant are described at some length. Numerous infection experi- 

 ments are reported in which the parasitism of the fungus was clearly established. 



Various methods are described for the prevention of the disease. It appears to 1 )e of 

 unusual occurrence and of little importance upon seedlings grown among grass, weeds, 

 or other plants; and it is recomftiended that mixed sowings should be made in the 

 nursery in which some protective species are introduced. Hedges and walls along 

 the west side of plantations are also protective to a considerable degree. The seed 

 bed for young pines should not be placed near pine forests. As there seems to be 

 evidence that the disease may be communicated through infested seed, special care 

 should be given seed selection, and the young seedlings should be made as resistant 

 as possible by promoting their rapid growth through cultivation and the use of fertil- 

 izers. A report is also given of experiments conducted at a number of different sta- 

 tions and covering several years, in which various fungicides were tested to determine 

 their value as a means for the prevention of the leaf cast. The best results were 

 obtained with fungicides containing some form of copper. Thorough and repeated 

 a{)plications of Bordeaux mixture, with or without sugar, or a copper-soda mixture, 

 protected the young seedlings from serious injui'y. 



Notes are also given of a disease resembling leaf cast caused by the larvtc of Dijilosis 

 (Ctridomyia) brachyniera, and statistics as to the distribution and injury caused by 

 leaf-cast diseases are presented. 



A disease of spruce twigs {Bui. Soc. Cent. Forst. Belg., 8 {1901), So. 2, 2»p. 63-74, 

 ]>h. 3, fig. 1). — An account is given of a disease of spruce caused by attacks of Seploria 

 parasitica. The disease usually makes its appearanc'e in May or June, when the 

 young shoots are rapidly growing and are quite tender. The leaves turn brown and 

 fall away, leaving the extremities of the limbs dead and bare. The fungus seems to 

 attat'k plants in the seed bed, as well as trees 20 to 50 years old. The disease 

 ordinarily begins in the tips of the branches, where growth is rapid and the water 

 renuirements the most pronounced, spreading from this jioint downward. The fun- 

 gus seems more prevalent in trees grown at considerable elevation or where there is 

 a diminution of the water supply and where the circulation of air and the light are 

 intense. The development of the parasite seems to be greatly favored l)y dry seasons. 

 In addition to the disease caused by Septoria the spruce trees are quite sustteptible to 

 attacks of Bolrytis doughtsli. 



The cacao disease {Trinidad Bat. DrpL Bid. Misc. Iiifortii., 1901, Xo. J7, }>. 32S). — 

 .\ brief account is given of the occurrence on the branches of cacao trees of growths 

 known as witches' brooms or hexenbesens. The cause of these growths is said to be 

 lyiKtsciis Uwohromir. The disease so far has l)een observed only in Surinam, and it is 

 reconnnended that wherever observed the deformed growth should l»e cut out and 

 the trees sprayed, as far as possible, with dilute Bordeaux mixture. 



Hexenbesen of cacao trees in Surinam, J. Ritzema 'Ron {Zlschr . Pjlanzfiikrinik., 

 11 {1901), No. 1, pp. 26-30, figs. 2). — A technical description is given of hexenbesens 

 or witches' brooms occurring upon cacao trees in Surinam. The author finds they 

 are caused by a new species of Exoascus to which the name J'J. (Iwohroiiiic is given. 



