DISEASES OF PLANTS. 747 



growing, and an abundant supply of water must be available to the roots ; either 

 factor alone is inoperative. 



On the basis of a study of gummosis, the author suggests as preventive and 

 remedial measures proper drainage, the use of resistant stocks, moderate root 

 firuning, slitting the bark of the diseased trees, and amendments to the soil in 

 the shape of lime and salt. 



After a similar study of squamosis and exanthema, the author concludes that 

 the former is a species of gummosis, and consequently that growth and water 

 are factors in its development, while exanthema is only differentiated from 

 gummosis by the erumpent pustules, and can, therefore, probably be considered 

 as only another form of gummosis. 



A bibliography is appended. 



Withertip of citrus trees, E. O. Essig i Pomona Col. Jour. Econ. Bat., 1 

 (1911), ^o. 1, pp. 25-56, figs. S).— The history and distribution of this disease 

 in citrus orchards is given, together with a description of its characters and de- 

 structiveness and the methods usetl in combating it. 



Attention is called to several local attacks of this fungus {CoUetotnclmm 

 fflaosijorioides) on lemon and orange trees on the Pacific slope during 1909-10, 

 especially in Ventura County, California, where serious losses have resulted to 

 citrus growers from this disease, which seems to be increasing in frequency and 

 severity. The results are also given of experiments on the control of this 

 disease by the use of lime-sulphur and Bordeaux-mixture sprays. The best 

 spray for this purpose is found to be a 4 : 4 : 50 Bordeaux mixture. The history 

 and control of this disease iii the Limoneira orchard is presented by J. D. 

 Culbertson. 



A new coffee disease (Phthora vastatrix), F. H. d'Herelle (An. Mus. Nac. 

 [San Salvador], Jf {19 10), No. 2S, pp. 182-1S9). — This is a summary of investi- 

 gations previously noted from other sources (E. S. R., 23, p. 749) on the life 

 history of this fungus, which the author has described as a new genus and 

 si>ecies. 



Two new fig^ diseases, C. W. Edgerton {Phytopatliology, 1 {1911), No. 1, 

 p. 12-17, pi. 1, fig. 1). — ^The author describes a fig canker in which the tissue 

 surrounding a fruit scar turns dark and shrinks, often showing a number of 

 pink pustules. The diseased area spreads until the branch is nearly girdled, 

 when the twig usually dies. In old cankers on branches 2 or 3 in. in diameter 

 the dead tissue cracks and finally falls out, leaving an open permanent wound, 

 which sometimes extends nearly to the center of the branch. Infection seems 

 to occur only in the fruit scar and within less than a j'ear after the develop- 

 ment of the fruit. The fungus producing the canker is described as a new 

 species, Tubercularia fici. 



The second disease discussed is a limb blight of the flg tree, which is charac- 

 terized by bright, salmon-colored fructifications on the branches and by the sud- 

 den wilting and dying of the leaves on infected areas. The fungus {Coriicium 

 Ixetum) generally gains a foothold in the tips of branches which have been killed 

 by the fig canker or by fig borers and spreads from there into the living tissue. 



On a parasitic fungus of the oak, G. Arnaxjd {Ami. Ecole Nat. Agr. Mont- 

 pellier, n. ser., 9 {1910), No. i, pp. 278-286, pi. 1). — ^A description is given of 

 Trabutia quercina, a parasite on the leaves of Quercus ilex and Q. coccifera, 

 which, the author claims, from its perithecial characters must belong to the 

 Pyrenomycetes. 



The oak mildew, its dissemination in Austria-Hungary, and its signifi- 

 cance in silviculture, G. Kock {Ztschr. Landw. Versuchsw. Osterr., 13 {1910), 

 No. 2, pp. 8.'i2-888). — It is claimed that this mildew is generally prevalent in 

 all the forests throughout this region where oaks are present. It appeared for 



