1918] DISEASES OF PLANTS. 153 



Report on the South American leaf disease of the Para rubber tree, O. K. 

 Bancroft {Reprint in Jour. Bd. Agr. Brit. Ouiana, 10 {1916), No. 1, pp. 13- 

 33). — It is stated that the leaf disease of Hevea appeared sporadically in Brit- 

 ish Guiana in 1909 and more abundantly in 1914, and that it is now more or 

 less prevalent in all parts of the colony except along the coast. It is said to be 

 caused by Fusicladium macrosporum. 



The characteristic symptom is the dying back of the branches toward the 

 stem. The rapidly reproducing form of spores occurs on young leaves and twigs 

 recently attacked, the other two (which may supposedly together represent a 

 resting stage) occur principally on old and fallen leaves. The same disease is 

 said to occur in Dutch Guiana and in Brazil. 



The leaf disease is affected by dryness (tending to defoliation) and by a 

 high day temperature. Leaves are most susceptible to attack when one or two 

 weeks old and 3 to 5 in. long. The disease has been observed on two wild forest 

 species of Hevea, but on no other wild plants. 



A Bordeaux spray is recommended. Sanitary measures include open plant- 

 ing; removal of fallen leaves, dead wood, and wild Hevea; and treatment of 

 wounds with tar or some other reliable disinfectant. 



Control measures for the South American Hevea leaf disease, G. Stahel 

 Meded. Dept. Landb. Snriname, No. 6 {1916); hidische Mercnur, 39 {1916), 

 No. JfS, pp. 986, 9S7). — This is a reprint of a pamphlet summarizing the con- 

 tents of a forthcoming bulletin. 



The author states that the Hevea leaf disea.se fungus has three forms of 

 fructification, perithecia, pycnidia, and conidia, all of which were studied, the 

 conidia (the Scolecotrichum form of fructification) proving to be almost the 

 sole means of propagation used by the fungus. While full-grown leaves are 

 somewhat resistant, young leaves are readily infected. 



It is recommended that occasionally the young leaves and shoots be kept 

 down on affected estates for a period of from two to four weeks. Measures 

 proposed by Bancroft in his article above noted are criticized. 



Fighting the South American leaf disease of Hevea {Jour. Bd. Agr. Brit. 

 Guiana, 10 {1916), No. 1, pp. J-^).— This note refers to the work by Bancroft 

 and summarizes that of Stahel, both of which are noted above. 



An abnormal leaf fall in Hevea, P. Akens {Meded. Proefstat. Malang, No. 

 14 {1916), pp. 6-13). — In two cases of premature leaf fall observed to occur 

 during the heavy rains in the Malang country, a parasitic fungus was found 

 which is said to be Neozimmermannia {Glceosporium) elasticw. No definite re- 

 sult followed artificial infection with the organism, which may therefore depend 

 upon the sensitizing effects of wet weather. The leaf-fall organism of India 

 (Phytoplithora sp.) and the one found in Surinam have not yet appeared in this 

 archipelago. 



The efficacy of acid, neutral, or alkaline Bordeaux mixture, V. Vermorel 

 and E. Dantony {Notes Exp^rimentales sur Vcfflcacit6 des BouiUies Bordelaises 

 Acides, Neutres et Alcalines. Villefranche: Prog. Agr. et Vit., 1917, pp. 28, figs. 

 3). — Discussing the conflicting conclusions of various workers regarding the 

 relative values of acid, alkaline, and neutral Bordeaux mixture, the authors 

 give an account of tests made by them during 1915 and 1916 in which grape 

 leaves, after having been sprayed, were detached day after day and tested for 

 the presence of soluble copper. 



The results led to a certain modification of the views previously expressed 

 (E. S. R., 34, p. 540). It was found that in case of acid spray nearly all of 

 the soluble copper disappeared in two or three weeks or even during one good 

 rain, while in case of the alkaline solution a considerable portion of copper 



