Plant-Diseases and Insects. 



ii5 



and the old potato-rot, will come under the control of the 

 general grower. There is a distinct movement in favor of the 

 ammoniacal carbonate of copper, as compared with the Bor- 

 deaux mixture, as it is cleaner, cheaper, and much more 

 easily used. Among new fungicides, there are two which de- 

 mand record here. The more important is that prepared by 

 the Division of Vegetable Pathology of the National Depart- 

 ment of Agriculture last year, as 6 6 Mixture No. 5. " It consists 

 of equal parts of ammoniated sulphate of copper and carbon- Fungicides 

 ate of ammonia, thoroughly mixed and put up in air-tight 

 cans. A pound of this dry mixture is used to 30 to 50 gallons 

 of water. The material is cheap, costing about 45 cents per 

 pound, is easily prepared, and can be kept in the dry state 

 until desired for use. This material, which is essentially a dry 

 eau celeste, has been used with good results upon those fungi 

 for which the ammoniacal carbonate of copper and Bordeaux 

 mixture are employed. Lodeman* has found that the chlo- 

 ride of copper possesses merits which entitle it to trial for the 

 common plant-diseases. When used at the rate of three ounces 

 in 22 gallons of water, it gave better results upon squash 

 mildew {Odium erysiphoides var. Cucurbitaruni) than did the 

 Bordeaux mixture. 



Little progress appears to have been made this year in se- 

 curing any satisfactory new combination of insecticide and 

 fungicide. In 1890, Gillettef found that the addition of lime 

 to London purple renders the arsenic harmless to foliage, a 

 fact which led to the combination of the arsenites and Bor- 

 deaux mixture with good results. But when the ammoniacal 

 carbonate of copper and the arsenites are combined, arsenic 

 is dissolved by the ammonia, and the compound becomes very filicides, 

 caustic to foliage. Lodeman, J who has investigated this sub- 

 ject at length during the year, finds that the caustic action of 

 arsenites is increased, not only by the ammoniacal carbonate 

 of copper, but by the addition of other salts of copper, as 

 the sulphate, hydrate, borate and chloride. The insecticidal 

 and fungicidal values of the substances remain, however, after 

 the combination is made. Weed,§ however, recommends a 

 combination of arsenites and carbonate of copper, to which 



*i5ull. 35, Cornell Exp. Sta. (Dec. 1891). 

 f Annals for 1890, 94. 

 X Loc. cit. 



g Spraying Crops, 32. 



