18 PARIS GREEN SPRAYING EXPERIMENTS. 



On June 16 and 17 another set of sprayings was made on the plum 

 trees, the object being to obtain the cumulative effect of the sprays 

 and also to ascertain whether the same injury would be done at this 

 time as was noted after the sprayings of May 25 and 26. In this 

 experiment the plum trees previously used were again sprayed with 

 the same solutions and, in addition, some trees not used before were 

 treated. Solutions Nos. 1, 2, and 3 were applied on the afternoon of 

 June 16, and solutions Nos. 4, 5, and 6 on June 17. A rainfall of 0.19 

 inch occurred, however, on the same day, and the results with Nos. 4, 

 5, and 6 were entirely inconclusive, as no effect at all was produced, 

 except on protected portions of the lower leaves. 



The results obtained with Nos. 1, 2, and 3, applied on June 16 and 

 followed by 0.19 inch of rain on the following day, while not definite 

 enough for tabulation, plainly indicate that the last spraying did more 

 injury than the first, and this was especially noted in the case of the 

 trees which received two applications. The greater amount of injury 

 resulting from the second spraying can be easily explained, as at the 

 time of the first spraying the leaves were still } 7 oung and the weather 

 for four weeks previous had been extremely dry. Furthermore, from 

 the weather chart it will be seen that only a small amount of rain fell 

 during the three weeks following the spraying on May 25 and 26. 



CONCLUSIONS. 



The results obtained may be summarized as follows: 



(1) Of the apple, pear, plum, and peach foliages the apple is injured 

 the least, the pear and plum are affected to about the same degree, and 

 the peach is injured the most. 



(2) If only one application is made, Paris Green containing 4 per 

 cent of free arsenious oxid can be applied with safety to apple trees 

 and with the addition of lime 6 per cent may be present. 



(3) If only one application is made to pear or plum trees, Paris 

 Green containing 3 per cent of free arsenious oxid can be applied with 

 safety and with the addition of lime 5 per cent. 



(4) One application to peach trees of Paris Green containing 3 per 

 cent of free arsenious oxid can not be made with safety without the 

 addition of lime; with lime 4 per cent may be used. 



(5) Two applications will do more damage than a single one, and 

 more injury is apt to occur if the weather conditions were normal 

 previous to the spra}dng than if very dry weather obtained. 



Some observations were made on the manner in which the foliage 

 of the different trees is affected. On the apple tree the injury is indi- 

 cated b} r small, light-brown spots, well distributed over the leaves. 

 On the pear and plum trees the damage is indicated by larger dark- 



