. Department bulletin. Mav '.?. iH'jf). « jxt cent more diseased foliage on the control trees May 9 than April 22. The percentage of foliage of the sprayed trees showing disease had decreased, however, 5 per cent. Of the total foliage of the trees sprayed in 1894, but left unsprayed in 1895, 5 per cent more was diseased at the second date than at the first. These figures indicate that the divergence^ in the percentage of disease on sprayed and unsprayed trees was still increasing just prior to the second estimate. The second estimate may thus be considered as taken before any of the trees had
. Department bulletin. Mav '.?. iH'jf). « jxt cent more diseased foliage on the control trees May 9 than April 22. The percentage of foliage of the sprayed trees showing disease had decreased, however, 5 per cent. Of the total foliage of the trees sprayed in 1894, but left unsprayed in 1895, 5 per cent more was diseased at the second date than at the first. These figures indicate that the divergence^ in the percentage of disease on sprayed and unsprayed trees was still increasing just prior to the second estimate. The second estimate may thus be considered as taken before any of the trees had begun to recover from the eflfects of the disease. The time of maximum contrast was the true time to make the estimates, and it is believed the date of this second estimate was certainly not too late to fully comply with this requirement. This belief was substantiated b}" a third partial estimate made a week later, which gave in general very similar results to those obtained Ma}^ 9. It should also be said that the decrease in the percentage of disease on the sprayed trees between the dates of the first and second estimates did not indicate that the second estimate was made too late, or after the trees had begun to recover, but merely that the leaf buds had not fully pushed at the time of the first estimate. This is further shown b}^ the fact that the percentage of disease was still increasing on unsprayed trees up to that time. Before considering the action of individual sprays in saving the foliage from curl, the following comparisons are given of the action of the classes of sprays used: I Taklk 7.—Percentage of heaUky foliage on frees differently .^prayed. Percentages of healthy foliage shown by trees sprayed with different classes of spravs. Estimated April 23 and May 9,1895. Average of 30 trees sprayed with snlphur, lime, and salt Average of 70 trees si)rayed with sulphur and lime Average of 100 trees sprayed with the two preceding sulphur sprays Average of 90 tree
Size: 1565px × 1597px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherwashingtongovtprin
