DISEASES OF PLANTS. 987 



To prevent the disease it is suggested that the affected pods be gathered and 

 burned, or so deeply buried thai the spores will doI be brought to the surface. In 

 order to prevent spread toother pods the trees should lit- well Bprayed with Bordeaux 

 mixture. 



The cocoa disease in Surinam | Trap. Life, 1 I 1905), No. 1, />. IB). A brief 

 account is given of the spread of the cacao disease in the Wesl indies, and a letter 

 from J>r\ Van Hall is ooted, in which ii is stated thai the witch-broom disease has 

 been under investigation )>y him for about 9 months, bul as yel he has been unable 

 to ascertain definitely the means of its dissemination. It is believed probable thai 

 the spores are spread principally by the wind. I>r. Van Hall states thai while the 

 disease firsl appeared in Surinam, it is now known as occurring in Demerara, where 

 it is spreading, and will probably cause greal loss, tn Surinam this disease has 

 reduced the export from 31,630 bags of 100 kg. each in 1901 to 8,540 in 1904. 



The silver-leaf disease [Gard. '/nun.. .;. set., 88 1906 . No. 971, p. til). A 

 brief note is given on inoculation experiments carried on by Professor Percival at 

 Reading. 



It" by a process similar to budding a small fragment of the fungus or portion of the 



leaf affected with the characteristic discoloration he inserted in the hark of plum 

 trees, after some time, varying according to season, the silvery appearance shows 



itself in the foliage where before all was green. This peculiar appearance is due to 

 the detachment or raising of the epidermis of the leaves from the adjacent tissue. 

 So far no fungus has been found in the leaves, and it is intimated that probably the 

 disturbance is caused by some ferment or enzym secreted by the fungus, winch 



reaches the leaves from the wound. 



Tlu' disease seems to be confined to the stone fruits, and it occurs under glass as 

 well as in the open air. The only remedy at present known is to cut away the 

 affected branches and induce the tree to make new growth, hut experiment- have 

 shown that this is not at all satisfactory. 



Combating- the pine leaf cast, Schalk | Forstw. Centbl., n. ser., .'? i 1905 >. No. 11, 

 />/>. 561-570, pi. 1). — The pine leaf cast, due to the fungus Hysterium pinastri, is 

 described and notes given on experiments carried on for its control. 



The author claims that even in regions where the disease is very prevalent it can 

 be prevented by thorough spraying and the proper use of fertilizers. A Bingle 

 annual spraying in the seed bed will usually he sufficient, ami if carried on for 1 

 years strong plants will he produced and the dominant ones will he free from 

 disease. In the nursery rows at least 2 sprayings should be given the trees annually. 

 This, together with proper fertilizers, will enable the young plants to withstand the 

 leaf cast. 



Winter treatment against fungus diseases, L. Degrully [Prog. Agr. et Vit. 

 | Ed. VEti), 26 \ 1905), No. 49, />/>. 641, 64$).— The author points out editorially tin- 

 advantage to be obtained by the use of strong solutions of fungicides as winter treat- 

 ment against various grape diseases, and he recommends treating the vines during 

 the dormant season with strong solutions of potassium sulphate, calcium bisulphite, 

 and iron sulphate for the prevention of powdery mildew, or with solutions of copper 

 sulphate and bichlorid of mercury for preventing downy mildew, black rot, and 

 powdery mildew. 



Fungicides and their use in preventing diseases of fruits, M. B. Waith 

 ( U. S. l)'j>t. Agr. t Farmer^ />'"/. B48, i>i>. SB, figs. 17). — The object of this bulletin is 

 to give the principal formulas for fungicides, together with brief descriptions of their 

 methods of preparation, and a summary of the principal disease.- of fruits lor which 

 satisfactory remedies have been found. 



