STATB POMOLOGICAL SOCIETY. 5^ 



familiar with the use of the two most common insecticides, viz. : 

 Paris green and London purple, one of the most noticeable features 

 is the great lack of uniformity in results as to the proportion of 

 sound fruit thereby saved by different orchardists and also as to the 

 injury done to the foliage. This injury to foliage is always liable to 

 happen to a greater or less extent, when the numerous conditions or 

 factors involved in successful spraying are not well understood in 

 theor}' and carried out in practice. 



Let us now examine briefl}^ some of the conditions or factors on 

 which successful results in sprayiug depend. The Grst one I will 

 mention is the use of the best insecticides which involves a consider- 

 ation of the comparative merits and demerits of London purple and 

 Paris green. One of the greatest objections to London purple is its 

 entire solubility in water, hence where used in the same proportion 

 as Paris green it often scorches the foliage and scars the young fruit 

 to such an extent as to ruin both for the season. Paris green on the 

 other hand being but slightly soluble in water proves when used in 

 the right proportion not only much safer for the foliage but also 

 equally effective in destroying the young larvse in the calyx of the 

 fruit. 



A second point of merit in Paris green over London purple is 

 found in the fact that while both of them are liable to adulteration, 

 the Paris green is usually but slightly so, being of much more uni- 

 form strength than London purple, so that by getting it of a reliable 

 chemist or manufacturer, a nearly pure article of known strength 

 may be used. London purple on the contrary, as is well known, is 

 always adulterated so as to vary greatly in strength, consequently it 

 is impossible to tell without first testing each lot used, by spraying 

 it on foliage and waiting several days or a week to see if injury is 

 done by either its unknown strength or its perfect solubility ; whereas 

 the Paris green, being of known strength and nearly insoluble in 

 water, makes it a much safer insecticide. 



Having found from its greater purity and insolubility that Paris 

 green is much the safer remedy of the two for the foliage, and equally 

 effective in results, a most important question to answer is, what 

 quantity effective as an insecticide can be used without injuring fruit 

 or leaves of the apple tree. Before attempting to answer this, allow 

 me to mention several important conditions or factors in the science 

 of spraying which have an important influence in the results, viz. : 

 1st, the variety of tree, as of apple or plum ; 2d, the youth or matu- 



