SPRAYING EXPERIMENTS AND APPLE DISEASES. 15 



of lead were used alone in 50 gallons of water scab was better 

 controlled than on all other plots except those where bordeaux 

 mixture and the stronger lime-sulphur were applied. More- 

 over, it will be seen on reference to the table that a greater 

 percentage of perfect apples was obtained from this plot than 

 from any other in the series. That even small or medium ap- 

 plications of arsenate of lead possess a distinct fungicidal value 

 is readily seen by comparing the check plot, number 7, with 

 plot 8 adjoining it where one pound of the powdered form was 

 used in 50 gallons of water. Here the amount of scab was re- 

 duced from nearly 39 to less than 16 per cent and the percentage 

 of perfect apples obtained compared very favorably with those 

 plots on which fungicides had been used in addition to the 

 same amount of powdered arsenate of lead as was used on 

 plot 8. 



While the writer is not ready as yet, without repeated experi- 

 mental tests, to recommend so radical a departure as placing 

 entire dependence upon arsenate of lead alone for the control of 

 scab and insect enemies in apple orchards in Maine the results 

 so far obtained are certainly encouraging. It is not beyond the 

 range of probability that efficient scab control with a minimum 

 of fruit russeting might be obtained b}^ using a dormant spray 

 of strong lime-sulphur or bordeaux mixture before the leaf- 

 buds open and then for later applications nothing but from 

 I 1-2 to 2 pounds of powdered or from 3 to 4 pounds of the 

 paste form of arsenate of lead in 50 gallons of water. Since 

 practically all the foliage and fruit injury from lx)rdeaux mix- 

 ture comes from the later applications still greater efficiency in 

 scab control might be obtained with no added danger from rus- 

 seting and leaf spotting if this is used when the flower buds 

 are showing pink. Such a procedure would entirely eliminate 

 lime-sulphur except as a dormant spray where its use is ab- 

 solutely required in many orchards on account of the blister 

 mite and other insects. 



Objection to this use of still greater quantities of arsenate 

 of lead might be raised on account of the claim made by some 

 that the accumulation of arsenic in the soil from its continued 

 use as a spray material tends to produce detrimental effects on 

 the trees themselves. Headden has shown this to be the case in 



