1918.] DISEASES OF PLANTS. 767 



The greater duration of efficacy in case of alkaline sprays Is admitted, but 

 it is questioned whether the acid spray may not at the time of its application 

 prove more effective against these diseases. 



Mixtures of lime and sulphur, A. Cadoret (Prog. Agr. ct Vit. (Ed. VEst- 

 Centre), 38 (1917), No. 11, pp. 258, 259).— Oidium of grapevines is said to be 

 controllable by the employment of four or five applications of the residual 

 sulphur obtained in certain industries. This should be mixed with lime or 

 wood ashes in the ratio of 50 : 50 from the end of May to June 20 and in the 

 ratio of 60 : 40 between June 20 and August 1. 



Rust of grapevines, L. Ravaz (Prog. Agr. et Vit. (Ed. I'Est-Centrc), S8 

 (1917), No. 20, p. .'/63).— Pending further study of the phenomenon, a brief 

 description is given of an arrest of development in grapevines closely resembling 

 that due to injury from strong copper sprays, but appearing on vines which 

 have not been sprayed. 



Report of the plant pathologist, E. W. Bkandes (Porto Rico Sta. Rpt. 1916, 

 pp. 28-Sl, pis. 2). — In addition to an account of routine worls carrietl on by 

 the plant pathologist, a preliminary report is given of an investigation of banana 

 wilt or Panama disease. 



This disease, which seems to be particularly injurious to the Chamaluco 

 variety, was previously reported in Porto Rico (E. S. R., 36, p. 352). The 

 studies of the author have shown that it is due to a species of Fusarium which 

 is indistinguishable from that previously described as F. cubense, an amplified 

 technical description of which is given. Preliminary investigations have shown 

 the possbility of controlling this disease by sterilization of the soil. 



A more detailed account of the disease is to be given in a subsequent publica- 

 tion. 



The geographical distribution of the citrus diseases, melanose and stem 

 end rot, H. S. Fawcett (Johns Hopkins Univ. Circ, n. ser.. No. 3 (1917), pp. 

 190-193). — This is a discussion of Phomopsis citri as an example of the failure 

 of a parasitic organism to extend itself to the limits of the territory occupied 

 by the host. In this case, it is suggested that humidity may constitute one 

 factor, but it is of limited value as an illustration owing to the absence of 

 melanose in southern Florida and in Cuba. Experimentation is now in progress 

 regarding the temperature relations of this fungus. 



Preliminary note on the relation of temperature to the growth of certain 

 parasitic fungi in cultures, H. S. Fawcett (Johns Hopkins Univ. Circ, n. ser., 

 No. 3 (1917), pp. 193, 19If). — This is an account of a study intended to compare 

 the temperature-growth curves for cultures of a number of fungi producing 

 diseases of citrus trees, but limited in their geographical distribution, with a 

 view to the interpretation of the observed facts of distribution and seasonal 

 occurrence and the suggestion of control measures. Cultures on solicl media 

 were studied as to daily growth under controlled conditions, and the results 

 are detailed. 



In marked contrast with the observed results reported by other workers, the 

 author notes the fact that Pythiacystis citrophthora exhibited no time diminu- 

 tion of growth rate, which often continued unchanged for a period of eight days 

 or more. 



The June drop of Washington navel oranges, J. E. Coit and R. W. Hodgson 

 (California Sta. Bill. 290 (1918), pp. 203-212, figs. 3).— A progress report is 

 given of a study of the June drop of this well-known variety of oranges. In the 

 previous publication (E. S. R., 37, p. 154), Alternaria citri was said to be the 

 cause of the disease. Later investi-gntion (E. S. R., 37, p. 834) seemed to indi- 

 cate that abnormal water relations also influence the dropping of fruit 



