mSEASES OF PLANTS. 351 



fnngrus or bacterium, and it is thought probable that the trouble is of physio- 

 logical origin. 



Better attention to the trees, removal of all dead wood, cultivation, fertilizing, 

 etc., will, it is believed, improve the condition of the trees and reduce the 

 amount of injury. 



A second contribution to the study of g-ummosis of orang-e, M. S. Bektoni 

 (Agronomia [Ptterto Bertoni], 5 (1913), jSfo. 3--^, pp. 93-97).— The author gives 

 a second report (E. S. R., 28, p. 651) on gummosis of orange, distinguishin-g 

 between this trouble and foot rot as seen in the United States. It is stated 

 that orange gummosis is a disease of defective nutrition and may be caused 

 or favored by poverty of soil or lack of certain elements of fertility; by lack 

 of water, or its excess with iK)or drainage ; by acidity of soil ; by poor cultiva- 

 tion, resulting in an impermeable layer near the surface; or by other condi- 

 tions affecting the normal course of nutrition, and that it may be prevented or 

 remedied by proper drainage, fertilization, etc. 



Silver thread blig'ht of coffee in Surinam, J. Kuijper (Dept. Landi. Suri- 

 name Bui. 28, 1912, pp. 11-24, P^^- 2). — As a result of the author's studies 

 on tliis disease of coffee, it is stated that in Surinam it attacks both Coffea 

 libericn and C. aralrica, forming rhizomorphic strands which extend up the 

 branches, spreading out over the undei* side of the leaves. The delicate hyphse 

 obstruct the stomata, which however they do not invade until near the death 

 of the guard cells. Large brown spots appear on the leaves affected, which 

 finally die and loosen, being retained however by the mycelial strands. 



The fungus is said to show no fructifications, but infection with the mycelium 

 spreads, destroying the leaves affected. The causal organism is believed to 

 be identical with neither Pellicularia kol&roga nor candelillo from Venezuela, 

 but to be strictly so with the coffee blight studied by G. P. Clinton in Porto 

 Rico following its description by F. S. Earle (E. S. R.. 16, p. 144). Bordeaux 

 mixture is recommended as a means of control of this disease. 



Black canker of chestnut, G. Bsiosi and R. Faeneti (Atti R. Accad. Lined, 

 Rend. CI. 8ci. Fis., Mat. e Nat., 5. ser., 22 (.1913), I, No. 6, pp. 361-366).— The 

 authors continue the controversy (E. S. R., 25, pp. 149, 850) as to the cause of 

 black canker of chestnut, this being a discussion of articles by L. Petri (E. S. R., 

 29, p. 156). They claim that Endothia radicalis is almost universally a sapro- 

 phytic fungus, only in exceptional cases showing limited activities as a wound 

 pai-asite, and that Coryneum is able alone to produce black canker of chestnut. 



Preliminary note on the relative prevalence of pycnospores and ascospores 

 of the chestnut-blig'ht fung'us during' the winter, F. D. Heald and M. W. 

 Gabdnek {Science, n. ser., 31 {1913), No. 963, pp. 916, 917).— In studying the 

 dissemination of the chestnut-blight fungus during the past winter the authors 

 obtained results which showed that pycnospores are produced in enormous 

 numbers and washed down the diseased trees during every winter rain. A 

 form of trap was devised by which part of the rain water falling over the 

 cankers was collected, and the number of pycnospores obtained in the different 

 rain periods was coimted. These varied after each rain from a few thousand 

 to several million. On the other hand, the ascospores did not appear to be 

 washed down the tree during the winter rains, although they were present in 

 abundance. The investigations on the ascospores indicate that there is practi- 

 cally no expulsion of them during the period from November 26 to March 21. 



Bubber tree diseases, T. Petch {Trap. Agr. and Mag. Ceylon Agr. Soc, 39 

 {1912), No. 4, pp. 321-325; abs. in Teysmannia, 24 (1913), No. 1, pp. 60-62). — 

 In an address on Hevea canker in Ceylon before the Kalutara Planters' Asso- 

 ciation, the author states that this disease is characterized externally by an 



