DISEASES OF PLANTS. 647 



study of the seedling and root rot diseases of sugar beets throughout the 

 country. 



By carefully controlled experiments with pure cultures, 4 fungi have been 

 demonstrated as causal agents in various seedling troubles. These fungi are 

 Pythium deharyanum, Aphanomyces Iwvis, Phoma betw, and a species of 

 Rhizoctonia, probably identical vs^ith that described as Corticium vaguni solani. 

 P. batw was found invariably present on beet seed, but so far it has not been 

 isolated from the soil. The other species appear to be soil organisms and were 

 never found on the seed. 



On two species of Heterosporium, particularly H. echinulatum, W. J. Dow- 

 son (Mycol. Centm., 2 (1913), Nos. 1, pp. 1-1 J^, figs. 3; 2, pp. 78-88, figs. 3; 3, 

 pp. 1S6-1U, fig. 1). — The author states that a new species of Heterosporium has 

 been found on the lower leaves of Beta vulgaris, and it has been named H. hctce. 

 It is stated also that the forms previously described as H. hetce and Eorvu.lcn- 

 ron sp. are saprophytes or very weak parasites. The parasitic uature of H. 

 e<;hinulatum was again confirmed, the carnation disease being spread by conidia 

 or spores of this fungus carried by wind or rain. 

 A bibliography is appended. 



Notes on the fundus diseases of sugar cane in Porto Rico, J. R. Johnston 

 {Abs. in Phytopathology. 3 (WIS), No. 1, p. 75).— The author reports upon a 

 number of diseases of sugar cane. 



Marasmius sacchari is said to be the most common sugar cane fungus in 

 Porto Rico, having been positively identified on living cane and cane trash 

 as well as on other plants. CoUetotrichum falcatum is said to be found not 

 only on cane but aLso on the dead petioles of the papaya. Thielaviopsis para- 

 doxa, Thyridarin tarda, Nectria laurentiana, and Spegazzinia ornata are re- 

 ported as occurring not only on cane but also on other plants. Melanconium 

 sacchari is also reported to be common. Cane smut, cane rust, and the yellow 

 gumming disease have not yet been reported as occurring in Porto Rico. 



Fusarium batatatis, not Nectria ipomceae, the cause of the sweet potato 

 stem rot, L. L. Haetee and Ethel C. Field {Abs. in Phytopathology, 3 {1913), 

 No. 1, p. 68). — The stem rot of the sweet potato, it is said, is usually regarded 

 as caused by N. ipomww. However, numerous inoculations, both in the green- 

 house and in the field, have failed to produce the disease. Sometimes there 

 was injury at the point of inoculation, but the fungus never entered the bundles 

 of the stem, and attempts to isolate it from the living tissue have always 

 failed. Another organism, however, was isolated from the fibrovascular bimdlea 

 of the roots, petioles, and stem, and this was found by a large number of 

 inoculations to cause the stem rot. The organism is a new one, and the name 

 F. batatatis has been given it by Wollenweber. 



Conditions influencing infection of apple leaves by Gymnosporangium 

 macropus, H. R. Fulton {Abs. in Phytopathology, 3 {1913), No. 1, p. 112). — 

 According to the author, inoculation tests and observations on natural infection 

 indicate that the individual leaf passes from a condition of immunity when 

 the leaves are very young and reaches a maximum susceptibility when they 

 have attained about half their full size. With increasing age the leaves become 

 less susceptible and finally immune. On twigs the infection is said to occur 

 in zones of usually 3 to 5 infected leaves, in which there is a decrease in the 

 amount of infection from the intermediate leaves upward and downward toward 

 those younger and older at the time of infection. 



The effect of Gymnosporangium on the transpiration of apple trees, H. S. 

 Reed and J. S. Coolet {Virginia Sta. Rpts. 1911-12. pp. 82-90, fig. 1) . — The 

 results of studies on the transpiration of apple leav&s affected with the cedar 



