174 Journal of Agriculture, 'Victoria. [lo March, 191 2. 



saving, as pointed out above, but an even greater saving is possible by 

 the use of oxychloride. To quote Professor Chuard — 



This product, now on the market, is obtained directly from copper, in the 

 electrolytic manufacture of soda or potash by the Granier process, which is based 

 on the use of metallic copper anodes. 



It is a pale green, non-crystalline powder, insoluble in water, but capable of 

 remaining in suspension sufficiently to permit of its regular application. It 

 possesses remarkable adherence, a fairly general property, in fact, of oxychlorides. 



This product contains 50 per cent, of copper. At the rate of 500 grammes 

 per hectolitre (i lb. to 20 gals.) it has regularly given results at least equal to those 

 obtained from a mixture based on 2 per cent, copper sulphate. This means a 

 reduction of 50 per cent, in the quantity of copper used. 



He explains the efficacy of reduced doses of tliis substance as 

 fallows :- - 



Oxychloride of copper exposed to air and moi'^ture, as it is after its application 

 on the leaf, undergoes oxidation which gives rise, progressivel}-, to small quantities 

 of soluble cupric chloride. This formation .... of a readilv ionizable com- 

 pound, explains in the clearest and most satisfactory manner the superiority of 

 copper oxychloride over hydrate or carbonaLe^'" those much less dissociable forms 

 under which copper is to be found in copper-containing spravs. 



Apart from theoretical considerations, however, oxychloride has been 

 extensively tried on a practical scale and has given excellent results. It 

 appears, in fact, to be the recent introduction which has most to recom- 

 mend it from all points of view. In addition to its use as a spray, it 

 constitutes an excellent fungicide powder when used in the dry state. 

 As we shall see presently, copper-containing powders are becoming very 

 popular, not as substitutes for, but as a complement to, spray mixtures. 



SUBSTITUTE.S FOR COPPER. 



Other metallic salts besides those of copper possess fungicide pro- 

 perties, and some of them have been tried for the treatment of fungus 

 vine diseases of the vine. A few years back, mixtures containing mer- 

 curv were recommended, and, after trial, abandoned as being less satis- 

 factory than the copper sprays they were intended to replace. 



More recently still, silver has been suggested as a substitute for copper. 

 Though the employment of a noble metal for spraying purposes might 

 seem extravagant at first sight, it is economically feasible,' the deadly 

 effect of silver salts on fungi rendering possible the use of very much 

 weaker sprays. The strength recommended is \ oz. of nitrate of silver 

 to 10 gals, of water. It is made into a mixture witli soap, of which 

 2\ ozs. are mixed witli the above quantities. This silver soap spray 

 possesses excellent wetting power, which renders it suitable for treatment 

 directed against mildew of the bunch {Rot Oris) ; the greasy nature of 

 the new-formed fruit causing it to be difficult to properly wet with 

 Bordeaux mixture. It appears to have more effect on hunch mildew than 

 against the same fungus on the leaves. It has been tried on a practical 

 scale with contradictory results, and does not appear likely to displace 

 copper as the basis of fungicide spravs for general use. 



Copper-Containing Powders. 



Being much easier and cheaper to apply, powders were long since 

 extensively experimented with as substitutes for liquid sprays. It 



* In copper-soda mixtures the copper is present in the form of liydrated rarbonrtte. 



