April, '14] 



DEW: ARSENATE OF LEAD 



165 



4. Basic arsenate of lead, under the climatic conditions prevailing 

 while the experiment was being conducted, became too slowly avail- 

 able to give good results even when double quantities were used. 

 In fact there was little difference between the effect of 1 pound and 

 3 J pounds. (Plots 1 and 4). 



During this series of experiments, in fact within three days after 

 the beginning of the examinations, two classes of fallen fruits were 

 distinguished, viz.: those normally shed (peaches shed naturally by 

 reason of overproduction, retaining the stem) and, second, those 

 abnormally shed (peaches shed b}- reason of some injury, the stem 

 remaining on the tree). After careful examination of the abnormally 

 shed fruits they were divided into two distinct groups, viz.: those 

 containing a feeding or egg puncture made by curculios or other 

 insects, and second, those showing no insect injury but having a 

 slight shriveled area at the base, caused presumably by the effect of 

 spray solution which had collected at that point. 



A careful daily record was kept of these classes of fallen fruits 

 both from the sprayed and unsprayed plots. That the abnormal 

 shedding which could not be attributed to insect injury was due to 

 the effect of arsenicals is indicated by the fact that the unsprayed 

 check plots gave less than 2 per cent of this class of fruits. However, 

 the figures given below show the results of these examinations. 



Note. — No sprayed plots showed burning of foliage to any large extent although sprayed trees shed a few more 

 leaves than those not sprayed. 



Believing this shedding to be caused by the arsenicals contained 

 in the spray the next points to be determined were: What form of 

 arsenate of lead causes the most shedding and does the shedding 

 vary directly with the units of AS2O5? The data accumulated on 

 this point is given below. 



TABLE V 



