180 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



author considers it probable that the disease is carried over to the next 

 season on seeds from diseased plants, — F. J. C. 



Sweet Potatos, Triehoderma Koningi, The cause of a 



Disease of. By M. I. Cook and J. J. Taubenhaus {Phijtopathology, 

 i. 6, pp. 184-9; plates). — The disease described is a dry rot which 

 spreads in the tubers in all directions from the point of origin and 

 completely girdles the tubers. The fungus Trichoderina Koningi was 

 isolated from the diseased spots and grown in pure culture. It was 

 found to reproduce the disease readily when it gained an entrance into 

 the plant through a wound. The disease is characterized by spots at 

 first circular and light brown with a tendency to wrinkle. The flesh is 

 hard and water soaked, brown with . a black izone around it. A 

 luxuriant white mycelial growth is formed on the surface of the 

 diseased area after some time. The symptoms are similar to, but not 

 quite the same as, those found in the tubers in store. A comparison is 

 made between the fungi Triehoderma Koningi and T. lignorum and 

 their growth characteristics described. Both species are capable of 

 causing a rot of sweet potato. — F. J. G. 



Symbegonia rubro-villosa {Bot. Mag. t. 8409).— New Guinea. 

 Family, Begoniaceae. Herb, 5-8 feet high. Stems tinged with red. 

 Leaves very unequal at the base and auriculate, 2^ inches long. 

 Flowers, monoecious; calyx (perianth) segments, males 2, females 5, 

 gamosepalous ; corolla, pale yellow campanulate. — G. H. 



Tar on Roads, Influence on Suprounding" Vegetation. By 



J. -Ph. Wagner (Jour. Sac. Nat. Horf. Fr. ser. iv. vol. xii. p. 511, 

 Oct. 1911). — A note on what seems to be the established fact, that the j 

 dust from tarred roads is harmful to surrounding trees and plants, both j 

 by clogging their pores and by its direct chemical action. Modern 

 traffic unfortunately makes tarred roads a necessity. It is, therefore, I 

 for horticulturists to discover the means of counteracting or evading 

 these ill effects. One suggestion is that only such trees and plants 

 should be grown in the neighbourhood of main roads as are known j 

 not to suffer. On the other hand, Mr. Lloyd-Davies, Engineer of 

 Koads and Bridges in Egypt, is convinced by his observations that the 

 dust is only harmful for the first fifteen days after the tar is applied, 1 

 so that if all dust were prevented for that time he considers that no j 

 bad results would follow. — M. L. H. 



Tarred Roads, Effect on Vegretation in vicinity. By L. 



Mangin (Rev. Hort. pp. 417-9; Sept. 16, 1911; 3 illustrations).— 

 Eeport of results demonstrating that the tarring of roads is detri- j 

 mental to adjacent trees. The illustrations show the destructive 1 

 effect on foliage of Catalpa, Eobinia, and Acer observed along j 

 thoroughfares partly tarred and partly not. The foliage in the former j 

 case is much reduced in size, and defectively developed. This is 

 imputed to poisoning by tarry emanations and also by the deposition 



