846 EXPERIMENT STATION RECORD. [Vol.36 



[Plant diseases in British Guiana], C. K. Bancroft (Rpt. Dept. 8ci. and 

 Agr. Brit. Guiana, 1914-15, App. 2, p. 13). — In the annual report on scientific 

 Investigations in the botanic gardens during 1914-15, the author states that the 

 principal diseases affecting imported sugar cane during the year were the leaf 

 spot (Leptosphcpria sacchari) and leaf sheath spot Cercospora vagince). Other 

 cane diseases mentioned are the root, or dry disease (Marasmius sacchari) and 

 two rind diseases caused respectively by Tricfiosphceria sacchari and Melanco- 

 nium sacchari. 



Coconut bud rot, apparently associated with defective drainage or other ad- 

 verse soil conditions, continued to be prevalent in some localities. Witches' 

 broom disease of cacao has proved to be amenable to treatment by pruning and 

 spraying. 



Two new root diseases appeared on one lime plantation, due respectively to 

 Fomes semitostus and Hymenochcete noxia. Citrus knot was reported from the 

 same plantation. The causation has not been determined, though it may be due 

 to attacks of bird vine (Loranthus theobroirus) . 



Coffee anthracnose (Colletotrichum sp.) was largely controlled by repeated 

 spraying with Bordeaux mixture and the destruction of affected leaves and 

 fruits. 



The leaf disease of Para rubber mentioned in the report of the previous year 

 (E. S. R., 34, p. 442) has done considerable damage. 



Blast of rice, due to Piricularia oryzce, is recorded for the first time, but it is 

 probably not yet widely prevalent. 



[Plant diseases in Tasmania], H. M. Nicholls {Agr. and Stock Dept. Tas- 

 mania, Rpt. 1915-16, pp. 18-20). — The annual report of the government micro- 

 biologist, besides mentioning some insect pests of plants, gives a brief account of 

 Armillaria mellea, causing damage to young apple orchards and apparently 

 benefited by the use of potassium permanganate, picric acid, and iron sulphate 

 on the roots. A Septogloeum, supposed to cause a disease of field peas ; Fusa- 

 rium oxysporum, causing wilt disease of potato; Irish blight in some sections; 

 a Fusarium causing leaf wilt and the speedy death of young fruit trees, par- 

 ticularly apple; Valsa prunastri and V. ambiens, usually on apple trees 

 killed by Fusarium; and mildew of cereals (Erysiphe graminis) are also noted. 

 Experiments for the prevention of brown fleck of potatoes are still in progress. 



A physiological study of two strains of Fusarium in their causal relation 

 to tuber rot and wilt of potato, G. K. K. Link (Nebraska Sta. Research Bui. 

 9 {1916), pp. 3-45, figs. 13; Bot. Gaz., 62 {1916), No. 3, pp. 169-209, figs. 13).— 

 An investigation was made of two species of Fusarium occurring on the potato 

 to determine whether there is a sharp biological contrast between the species, 

 as claimed by Wollenweber (E. S. R., 29, p. 444), and if so, to what physiological 

 basis this contrast is to be attributed. As a result of his studies, the author 

 concludes that there is not so sharp a contrast as would be expected from the 

 paper cited. 



A detailed account is given of the ecology and physiology of the organisms 

 causing tuber rot and wilt of potato, and it is reported that F. tuberivorum 

 (E. S. R., 29, p. 47) and F. trichothecioides (E. S. R., 27, p. 650) are identical. 

 Studies of this species and F. oxysporum showed that both can produce tuber 

 rot and wilt of the potato plant. Wilt is induced by the destruction of the root 

 system and by clogging the xylem elements in the stem. In mild cases it is 

 characterized by discoloration, curling and rolling of the leaves, production of 

 aerial tubers, etc. Under field and storage conditions F. oxysporum is probably 

 more responsible for wilt than is F. trichothecioides, while the latter is more 

 responsible for tuber rotting. The biological characters of the different species 

 are described at length. 



