DISEASES OF PLAXTS, 149 



The eradication of cankers greatly reduced the number of early infections 

 of the disease, although the removal of all small dead parts, such as the tips 

 of fruit spurs and small mechanically injured places, is not considered prac- 

 ticable. 



The natural modes of distribution of pear blight in California, B. J. 

 Jones (Mo. Bui. Com. Uort. Cal., 3 (1014), ^'o. 12, pp. 505-511, figs. 2).— The 

 principal carriers of i)ear blight discussed are honej-bees. flies, auts, pear thrips, 

 apple aphids, some insects living in the soil, of which several are named, and 

 the drip during rains. 



Black rot in Spain, L. Ravaz (Prog. Agr. et Vit. (Ed. VEst-C'entre), 35 

 (1914), No. 30, pp. 114, 115). — The author reports having found the characters 

 distinctive of black rot on both grapes and leaves of specimens sent for ex- 

 amination from the Province of Valencia, Spain, showing that this region has 

 now been invaded by this disease. 



Fung'us and other diseases of citrus trees, G. P. Darnell-Smith and E. 

 MACKINNON (Agr. Gaz. y. S. Wales, 25 (1914), No. 11, pp. 945-954, pls. 4)-— 

 In connection with appropriate fungicides and other remedial measures the 

 authors discuss briefly blue mold (Penicillium and Aspergillus), sooty mold 

 (C'apnodiuin citricoliim), melanose (Phmnopsis citri and Chidosporium iriinneo- 

 atrum), russetihg (Colletotrichum glaosporioidcs), Maori (supposedly physi- 

 ological), black spot (Phoma citricarpa), brown six)t (C. glososporiokles). 

 honey fungus (Armillaria utellea), collar rot (Fusarium limonis), scabbing 

 (Cladosporium), withertip and dieback (Phoma and Colletotrichum), and 

 exanthema and chlorosis (both physiological). 



Pseudomonas citri, the cause of citrus canker, Clara H. Hasse (U. S. 

 Dcpt. Agr., Jour. Agr. Research, 4 (1915), No. 1, pp. 97-100, pis. 2). — During 

 the summer of 1914 diseased material of grapefruit showing the canker was 

 received, and the author presents a preliminary report on the cause of the 

 canker. 



A microscopic study of the material showed the presence of bacteria and 

 these were isolated and proved pathogenic to grapefruit seedlings. A study of 

 the organism indicates that it is apparently a new species, and a technical de- 

 scription is given of it under the name P. citri n. sp. 



A number of investigators have reported the disease due to fungi, and the 

 author states that the open surface of the canker and the spongy character of 

 its structure afford an excellent lodging place for spores of all sorts and that 

 possibly fuagi may play a minor part in the later stages of the disease. 



Citrus canker in Florida and the Gulf States, H. S. Fawcett (Mo. Bui. 

 Com. Hart. Cal., 3 (1914), No. 12, pp. 512, 513). — This is mainly a summation of 

 information contained in several communications appearing in 1914 regarding 

 the appearance and progress of citrus canker. This has not yet reached Cali- 

 fornia, and it is thought that the drier climate would probably prove unfavor- 

 able to its power of destructiveness as shown in the eastern citrus-growing 

 region. 



The citrus canker situation in Florida, L. S. Tenny (Fla. Groivers and 

 fihippers League Bui. 1 (1914), pp. 16). — This is a summary of the papers and 

 discussions presented at the citrus seminar held at Gainesville, Fla., September 

 22-24, 1914. The speakers discussed the history of citrus canker in Japan and 

 in the United States, the favoring conditions, its appearances, spread, effects, 

 and dangers. The disease infects and matures quickly in warm, wet periods. 

 After infection nothing is known that will prevent the development of the 

 disease, though Bordeaux mixture and corrosive sublimate have been found 

 to prevent infection. 



