248 EXPERIMENT STATION" EECORD. 



inserted into cuts. The possibility of the action of enzyms In relation to this 

 disease was investigated, but so far as the investigations went no gumming re- 

 sulted. A detailed tabulated account is given of the results of inoculation ex- 

 periments witli Diplodia on a large number of trees. 



Report of plant physiolog'ist, B. F. Floyd (Florida Sta. Rut. 1912, pp. 

 ClI-CXIV, figs. 7). — The work reported upon is largely that on die-back of citrus 

 trees when grown under greenhouse conditions. The results of the investiga- 

 tions indicate that the pi'oduction of the die-back condition is connected with 

 the organic nitrogenous fertilisers. Instances were found, however, where die- 

 back occurred where no ferilizers had been used, and it is concluded that in 

 this case the casual factor is connected with the organic matter in the soil. 



In connection with the foregoing investigation, a study was made of the 

 gum pockets produced by die-back in citrus wood, and it appears that the gum 

 pockets are possibly a result of the action of enzyms. The enzyms suggested 

 are pectinase and hemicelluJase, and the presence of at least one of these was 

 demonstrated. 



Experim.ents on the decay of Florida oranges, J. G. Grossenbacheb (Z7. S. 

 Dept. Agr., Bur. Plant Indus. Circ. 12-'f, PP. 17-28, figs. 3). — According to the 

 author, oranges in Florida suffered severely during 1912 from decay, and the 

 present paper calls attention to the weather conditions, diseases, and injuries 

 sustained by the fruit in the groves, and the relation of these factors to decay. 



Oranges affected with melanose and ammoniation seemed to be especially 

 subject to the rot and an investigation was conducted to determine their rela- 

 tion to the trouble. In a previous publication (E. S. R., 28, p. 651) Floyd and 

 Stevens had calle(* attention to the relation of melanose to stem-end rot. The 

 author reports upon this briefly and calls attention to the fact that ordinarily 

 the fungus (Phoinopsis citri) is not to be found in the melanose rougheuings on 

 the leaves, shoots, or fruits. However, in certain unusually shaped spots, 

 termed stellate si)ots, the fungus has been found present, though not often. 



Some experiments were carried on to determine the cause of decay, particu- 

 larly in view of the fact ihat growers and shippers attribute most of the loss 

 to Fenicillium. Oranges were sprayed both in Florida and in Washington, 

 D. C, with spores of Fenicillium, and it was found that while there was some 

 blue mold decaj', most of it was due to Phomopsis citri. 



The author points out the impprtance of growing fruit free from melanose 

 and thus obviating a reduction in the market value of the fruit and also pre- 

 venting some splits and most of the stem-end rot, and that refrigeration prac- 

 tically prevented all decay in shipping tests conducted with this fruit. 



Black rot of the navel orange, E. O. Amundsen (Mo. Bui. Com. Sort. Cal., 

 2 {1913), No. 5, i)p. 527-53-',, figs. 5). — The author states that the navel orange 

 crop in California for a number of years has been affected by a disease vari- 

 ously known as black rot, navel rot, and black heart of the navel orange, due 

 to the fungus Alternaria citri, which has been previously described (E. S. R., 

 14, p. 459). The characteristics of the disease and the results of inoculation 

 experiments are described. 



Investigations of cacao canker, A. A. L. Rutgers {Dept. Landh., Nijv. en 

 Handel [Dutch East Indies], Meded. Afdeel. Plant enziek ten, 1912, No. 1, pp. 31, 

 pis. 3, fig. 1; abs. in Teysmannia, 2.) {1913), No. 1, pp. 68, 69; Mycol. CentltL, 2 

 {1913), No. Jf, pp. 223, 22//).— It is stated that PhytophtJiora faieri is the cause 

 of cacao canker, and that it causes the brown rot of cacao fruits and a canker 

 on Hevea ; also that the damage to cacao plants in Java, where the brown rot 

 is not so frequent, is less serious than in Trinidad and Ceylon. Investigations 

 sihowed that P. faheri is very closely followed by Nectria (Fusarium), and in 

 the fruits sometimes also by Thyridaria (Diplodia). 



