1916] 



DISEASES OF PLAKTS. 4^ 



Filosity in young potato plants, P. Passy {Jour. Soc. Nat. Hort. France, 4. 

 ser., 15 (1914), July-Dec, pp. 500, 501). — Of two potato tubers which had l)een 

 subjected to the same conditions, one was shown to have produced normal 

 sprouts, while the other exhibited a clearly marlied case of filosity. The facts 

 are supposed to refute the views of Parisot (E. S. R., 23, p. 148) that this 

 abnormality in growth is due to an accumulation of carbon dioxid during 

 storage. 



Downy mildew (Sclerospora macrospora) on rice, L. Gabotto ( Gior. Risicolt., 

 5 (1915), No. 18, pp. 292-294, fiff- !)• — A disease of rice is described as due to 

 S. macrospora. The head, if it emerges, is distorted and empty of grain, owing 

 to atrophy or transformation of the essential floral organs. 



A stem disease of sugar cane in Barbados, W. Nowetx (Agr. Neivs [Barba- 

 do.f], 15 (1910), No. 357, p. 14). — The author has examined a sugar cane disease 

 appearing in Barbados, said to be similar to or identical with that occurring 

 in India and described by Butler and Hafiz (E. S. R., 30, p. 650) as due to 

 Ccphalospor'mm sacchari. 



The disease appeared to be partly or entirely confined to canes whose water 

 supply had been interfered with as a result of wrenching by high winds or of 

 the development of Marasmius mcchari in the cane base. Some of the symp- 

 toms resembled tliose of red rot. Melan<:onium sacchari usually appeared as 

 a secondary infection. 



C. sacchari is thought to be widely distributed in the West Indies, and it 

 may be a factor in what appears to be a somewhat serious disease. 



Sweet potato diseases, L. L. Harteb (U. S. Dept. Agr., Farmers' Bui. 114 

 (1916), pp. 26, figs. 21). — This is a compilation of popular information regard- 

 ing sweet potato diseases, which, it is said, may be divided into three general 

 classes, those attacking the roots and stems, stem rot, black rot, foot rot, 

 scurf, and root rot; those of the leaf, leaf blight, white rust, and leaf spot; 

 and those developed in storage, soft rot, black rot, dry rot, Java black rot, and 

 charcoal rot. The different diseases are described and suggestions given for 

 their control. 



Apple rust, N. J. Giddings and A. Bebg (West Virginia Sta. Bui. 154 (1915), 

 pp. 4-73, figs. 41). — This is a detailed account of investigations of apple rust 

 and its control, a preliminary account of which has been noted (E. S. R., 33, p. 

 348). In the present bulletin, a technical account is given of the organism, 

 Gymnosporangium iuniperi-virginiance, its distribution, conditions for infecting 

 the host plants, and its physiological effect on both apple and cedar, after 

 which spraying and other methods of control are described. 



The authors report that apple leaves are susceptible only when young, and 

 that rust infection is not likely to take place after the first week in June 

 in the latitude of the station. Severe rust infections cause a deforming of the 

 fruit and a reduction in size, with a considerable loss of vigor in the tree. 



It is said that the disease may be controlled by the use of Bordeaux mix- 

 tnre, lime sulphur, or atomic sulphur, lime sulphur being the most efficient, 

 but the use of fungicides is deemed impracticable for commercial orchardists. 

 The destruction of cedar trees is considered a more effective method of con- 

 trol, and this has been carried out on a small scale, 1,113 acres being cleared 

 of cedar trees at a cost less than 48 cents per acre. 



A disease of apricot in Valais, H. Faes (Terre Yaud., 6 (1914), ^o. 25, pp. 

 282, 283). — Referring to a report made to the Department of A\alais, Switzer- 

 land, on a disease of apricot observed to be particularly severe at Saxon in 

 1914, the author states that the trouble, which is described as due to MoniUa 

 fructigena (M. laxa), causes much loss following damp weather and rains. 



