BASIC COPPER SULFATE AS A FUNGICIDE 145 



Grapes 



Spraying and dusting experiments were conducted in the College vineyard, 

 under the supervision of O. C. Roberts, to determine the relative effectiveness of 

 low and high basic sulfates (lots 6 and 7), Bordeaux 1.17-1.17-50 and a commercial 

 copper-lime-lead arsenate dust in controlling diseases on Worden grapes and 

 the amount of injury to fohage. 



The basic sulfates with lead arsenate and linseed oil 1.50-0.83 pt.-50 were 

 appUed as sprays at a concentration of 0.07 per cent copper and 0.07 per cent 

 arsenic, the same as Bordeaux 1.17-1.17-50 with lead arsenate 1.50-50. Chemical 

 hydrated lime was employed in preparing the Bordeaux. Oil was used with the 

 arsenic check spray but not with the Bordeaux. The basic sulfates, mixed with 

 lead arsenate and a free-flowing talc, were applied as dusts which coptained 3.00 

 per cent copper and 2.00 per cent arsenic. The commercial dust was guaranteed 

 to contain 3.94 per cent copper^ and 2.92 per cent arsenic. The arsenical check 

 dust was composed of lead arsenate and talc and contained 2.00 per cent arsenic. 

 The spray was applied under 75 to 100 pounds pressure with a double action, 

 Deming barrel hand-pump equipped with 2 Unes of hose to which were attached 

 rods and disc nozzles. The first two applications of dust were made with an 

 American Beauty hand duster which proved unsatisfactory because of its irregular, 

 intermittent discharge. The last application was made with a Peerless duster 

 which gave an even continuous flow. 



The fungicides were applied on the following dates and under the weather 

 conditions stated: 



June 7 — cloudy, humid, 68° Fahr. Spray and dust. 



July 16 — clear, moderate southwest wind. Spray. 



July 18 — clear, moderate southwest wind, 85° Fahr. Dust. 



August 13 — clear, 75° Fahr. Spray. 



August 14 — clear, humidity somewhat higher than on the 13th, 76° Fahr. Dust. 



Doran found a little downy mildew in the vineyard on August 22 and observed 

 traces on the check plot on September 11. No black rot was detected at any time . 

 As there was practically no disease during the season the efficiency of the several 

 fungicides could not be determined. Bourne noted a few leaf hoppers in the 

 vineyard uniformly distributed over the plots. 



Doran, Bourne and Roberts made the following observations on September 21 

 and 25 relative to foUage injury: 



Low basic sulfate spray — burn practically the same as for high basic sulfate, 

 adherence good. 



High basic sulfate spray — more burn than on check plot, spray residue adhered 

 well to fruit. 



Bordeaux — burn less than from basic sulfates, adherence good. 



Check — spray burn mild and generally distributed. 



Low basic sulfate dust — burn practically the same as high basic sulfate. 



High basic sulfate dust — no more burn than on check plot. 



The yield had no significance due to pilfering of the fruit and is omitted. 



In the practical absence of disease little could be learned of the relative value 

 of the fungicides. The commercial copper-Ume-lead arsenate dust was sticky 

 and would not flow freely (Roberts). 



Discussion of Results 



The results of the four years of field work appear to warrant the following 

 deductions as to the effectiveness of basic copper sulfate in controlling diseases on 

 various garden crops and fruits and the amount of injury likely to ensue. 



"Actually tested 4.28%. 



