754 EXPERIMENT STATION RECOED. [Vol. 37 



disease also attacks the stems and seed pods, but experiments indicate that the 

 fungus is not carried over in the living seed. 



The organism causing the disease has been isolated and inoculation experi- 

 ments have proved its pathogenicity. The organism is described by P. A. Sac- 

 cardo as C. higginscanum n. sp. The author believes that the disease occurs in 

 various portions of Georgia. 



Temperature relations of apple rot fungi, C. Brooks and J. S. Coo ley {Abs. 

 in Phytopathology, 7 (1917), No. 1, p. 76).— It is stated that most apple rot 

 fungi will grow at a lower temperature on corn-meal agar than on fruit and at 

 a lower temperature on ripe fruit than on green fruit. With several, if not 

 all, of the storage-rot fungi the initial stages of rotting are found to be more 

 inhibited at low temperatures than is the germination of the spores. Various 

 rots may finally make a fairly rapid development at temperatures at which 

 the fungus v< at first barely able to make a start. Even at favorable tempera- 

 tures most of the fungi pass through a period of incubation on apples that is 

 not evident on culture media. 



Black root rot of the apple, F. D. Fromme and H. E. Thom.\s (U. S. Dept. 

 Agr., Jour. Agr. Research, 10 (1911). No. 4, pp. 16S-1H, pU. S, fig. 1; abs. in 

 Phytopathology, 7 {1911), No. 1, p. 77). — The authors give a detailed account, 

 in continuation of a previous note (E. S. R., 36. p. 649), of their investigation 

 at the Virginia Experiment Station on the black root rot of the apple, which 

 is said to be an infectious disease of considerable economic importance In the 

 orchard sections of Virginia. 



No prominent leaf characters have been observed for the disease, but the 

 black encrustations on the surface of affected roots and the accompanying 

 dark zonatlons In the bark and wood are considered reliable diagnostic char- 

 acters. Field observations show that the root rot Is Infectious but that Its 

 progress Is comparatively slow. Apple trees planted on newly cleared land 

 are said to be moro liable to attack than those on land cleared and cultivated 

 for some time prior to planting. 



Three species of Xylaria have boon obtained In pure cultures from the apple 

 roots. X. hypoxylon, which proved to be an active wound parasite. X. poly- 

 tnorpha, which seems to be only slightly pathogenic, and an undetermined 

 species. X. hypoxylon is considered the chief cause of the root rot In Virginia. 



Exclusion of the fungus, proper attention to cultivation, and elimination of 

 contact with stumps of forest la'nd are recommended as control measures. 



Treatment of apple canker diseases, J. C. Whitten {Missouri Stn. liul. HI 

 {19tl), pp. 45, 44). — In a previous publication (E. S. R., 35. p. S48). the author 

 reported the checking of about 90 per cent of apple tree cankers by the use of 

 copper sulphate or corrosive sublimate. Obsei^atlons have been continued dur- 

 ing the past year to determine whether the cankers would break out again, but 

 no further progress has been noticed In wounds which were apparently healed 

 during 1913 and 1914. 



In connection with this treatment, the author reports that mixing corrosive 

 sublimate with paint has prove<l as effective In controlling canker as treating 

 the scraped parts with the disinfectant and later painting for protection. In 

 this treatment, the corrosive sublimate Is dissolved in turpentine and mixed 

 in proper proportion into the paint 



Jonathan spot, C. Brooks and .T. S. Cooley {Abs. in Phytopathology, 1 (1917), 

 No. 1, p. 16). — The authors claim that .lonathan spot increases up to a tem- 

 perature of 20° C. (68° F.). but it is entirely Inhibited at 30°. The dl.sease 

 It is said, t^n be readily produced in saturated air in closed moist chambers, 

 but seldom develops in a stirred air of 70 to 95 per cent relative humidity. 



