564 DISEASES OF CULTIVATED PLANTS 



smaller quantities of copper sulphate and lime than previously 

 used in the preparation of Bordeaux mixture give equally- 

 good results as the stronger mixture. 



The following is Dr. Shear's summary : 



Bordeaux mixture, prepared according to the 4-3-50 formula 

 (4 lbs. copper sulphate, 3 lbs. lime, 50 gallons water), has 

 been found quite as effective in preventing black rot as the 

 formulas in which larger quantities of copper sulphate and 

 lime are used. Five or six applications, beginning when the 

 shoots were eight inches to one foot long, gave generally as 

 good results as when one or two additional earlier applications 

 were made, showing apparently that no particular benefit is 

 derived from dormant applications or from applications made 

 when the shoots are less than eight inches long. 



Where unsprayed grapes were a total loss from black rot in 

 1907, the rot on the sprayed plots was reduced to 28-3 per 

 cent. The next season, 1908, when the rot was almost equally 

 bad on unsprayed vineyards, the rot on the same sprayed 

 plots was reduced to much less than one per cent., showing 

 apparently the great cumulative effect of treatment for two 

 seasons. 



The gain, due to spraying, varied in different vineyards, 

 according to the severity of the rot, the number of sprayings, 

 the productiveness of the vines, and the cost of materials and 

 labour, from io - 6o dollars to 62*30 dollars per acre. 



The experiments have shown the necessity of covering the 

 vines thoroughly with a fine spray of properl) pupated 

 Bordeaux mixture. When the black rot is serious or the 

 foliage is very heavy, it is necessary to use trailers and have 

 the nozzles directed by hand, as fixed nozzles will not pro- 

 perly cover the foliage and fruit 



The tests of various lime-sulphur preparations have not yet 

 been sufficient to determine their value as a preventive of 

 black rot. 



Neutral copper acetate, one lb. to fifty gallons of water, 

 has been found to he the best non staining preparation tested 

 in these experiments for final applications. 



Shear, C. L., U.S. Deft. 1 . Bur. PL Industry, bull. 155 

 (1909). 



Cucumber and mushroom bed fungus (Xylaria vaporaria, 

 Currey) often forms dense masses of irregularly shaped, vari- 

 ously branched, black, corky sclerotia in the soil of cucumber, 



