DISEASES OF PLANTS. 69 



sulphur 50 kg., mineral superphosphate 25 kg., and copper steatite 25 kg. is recom- 

 mended as a preventive measure against gray rot of grapes. This has been used for 2 

 seasons with success and according to the author did not produce any injurious or 

 deleterious effect on the quality of'the wine. 



The action of silver chlorid on the gray rot of grapes, G. Bouchardat [Rev. 

 17/., 20 {1903), No. 521, pp. 669, 670).— Based upon the investigations of Raulin, 

 which showed that ammoniacal solutions of silver chlorid had a strong fungicidal 

 action, the author reports upon this substance when used for attacks of Botrytis 

 cinerea. 



To prepare this solution the author dissolved 25 gm. of silver nitrate in 200 gm. of 

 water to which was added sufficient sea salt to precipitate the silver nitrate in the 

 form of chlorid. After precipitation strong ammonia was added sufficient to com- 

 pletely dissolve the precipitate, and 1 liter of the solution was made by the additii m 

 of water. When used 10 cc. of this solution was added to 12 to 15 liters of water 

 and sprayed upon the vines. 



The vines sprayed with this solution were protected against the attack of the fun- 

 gus until after the second invasion, which was very light on both sprayed and check 

 vines. 



The canker fungus in rubber, J. B. Carrcthers (Agr. Bid. Strait* <in>l Federated 

 Malay States, ..' {1903), Xo. 12, pp. 389-392).— An account is given of the canker 

 fungus of rubber, which is said to have been first noticed in 1901 by the Conservator 

 of Forests, but was not called to the author's attention until early in 1903. 



The disease is due to a species of Nectriaand an investigation showed that in some 

 districts from 0.5 to 2 per cent of the trees were affected, while in others as high as 

 40 per cent of the rubber trees were diseased. The presence of the fungus may be 

 generally recognized by the roughened and swollen appearance of the stems and 

 branches. If the outer hark is removed there is seen a discolored tissue which sul>- 

 sequently becomes brownish in color. The canker is spread by the agency of the 

 wind, insects, such as red ants, etc. 



As preventive measures the author recommends inspection and cutting out of the 

 diseased portions and the burning of all bark and dead branches. -When trees are 

 badly affected they should be destroyed, as the presence of the fungus tends to pre- 

 vent the production of latex by the trees. There is thought to be little danger of 

 the fungus attacking nursery stock, as the smooth bark of the young trees would, in 

 a measure, prevent the fungus gaining a lodging place. 



Investigations in Helicomycelium fuliginosum, E. Dubourg {Mem. Soc. Sci. 

 Phys. et Nat. Bordeaux, 6. ser., 3 {1903), pp. 263-272) .— A study is given of a fungus 

 observed in some worm-eaten railway timbers. The timbers prior to use had been 

 treated with creosote for their preservation, but the liquid had not penetrated to 

 their center and it was in this zone only that the fungus was found. 



Some of the morphological and biological characteristics of the fungus, which was 

 artificially grown on a number of media, are described. The fungus was found to 

 secrete oxydase abundantly, especially in unaerated media. An attempt was made 

 to determine the effect of various antiseptic solutions on the development of the 

 organism. It was found to grow in solutions that are usually strongly antisej it ic. 

 Copper sulphate, bismuth subnitrate, and potassium fluorid even when used as 

 strong as 1 part to 100 did not check growth. Corrosive sublimate, thymol, and 

 salicylic acid 1 to 10,000 were insufficient, but when used in strengths of 1 to 5,000 

 checked all growth. Phenol, naphthalin, creosote, and carbolineum 1 to 2,000 

 destroyed the fungus, and potassium arsenite 1 to 200 hail a similar effect. 



To test the practical application of different treatments of wood for preservation 

 when placed in the ground, experiments are to be conducted in which railway sleep- 

 ers are to be injected with a number of fungicides and their relative efficiency noted. 



5409— Xo. 1—04 IS 



