73 



Orchard I, because the original infestation of this orchard was so 

 high that an increase in plots 2, 3, and 4 at the rate of the check 

 plot, would have completely incrusted these trees long before the end 

 of the season. In other words, this orchard was too heavily infested 

 in the beginning to be fit for full use in our experimental program. 



By an inspection of the foregoing table we find that two treat- 

 ments, fall and spring, of the heavily infested orchard (the average 

 infestation of whose experimental plots was 7.67 degrees) produced 

 less effect than a single spraying, in either fall or spring, of the 

 moderately infested orchard (the infestation of whose experimental 

 plots averaged 3.9 degrees). The average improvement of plots 2 

 and 3 in Orchard I, the trees in which were twice sprayed with lime- 

 sulphur preparations, was 32.7 percent, while that of plots 7 and 8 

 in Orchard II, once sprayed in fall, was 39.4 percent, and that of 

 plots 11 and 12, once sprayed in spring, was 48.7 percent. This fact 

 illustrates clearly the importance of early spraying before infestation 

 becomes s'erious. In these experimental orchards there were but few 

 crawling young up to August 1 on any of the treated trees which had 

 originally been infested to 8 degrees or less ; while on trees grading 

 9 and 10 degrees, crawling young were fairly abundant thru July, 

 and began about the middle of August to cause a, considerable re- 

 infestation of surrounding sprayed trees, this dispersal increasing 

 rapidly as the season progressed. While the insecticide treatment 

 reduced a few of the completely incrusted trees to the 6th degree of 

 infestation, many of those incrusted at the beginning of the experi- 

 ment were partially or completely incrusted again by the end of the 

 summer. 



The records of the checks in both orchards show a seasonal in- 

 crease amounting to about one-third of the original infestation ; while 

 the lime-sulphur treatments of plots 2 and 3 in November and March 

 worked a reduction of about a third of the 8.5 degrees original in- 

 festation of these plots. There was thus every reason to believe that 

 a continuation of this program would save this orchard and virtually 

 clear the trees of the scale ; and this, I am informed, has since been 

 done, both of these orchards being now productive and in good con- 

 dition. 



The difference in effect between fall and spring spraying with 

 lime-sulphur was shown by a comparison of the ratio of benefit (52.2 

 percent) of plots 7 and 8, sprayed in fall, with those of plots 11 and 

 12 (61.3 percent), sprayed in spring — a difference of about 17 per- 

 cent in favor of the spring spraying. A similar comparison of the 

 ratios of benefit of plots 10 and 14, sprayed with Scalecide, gives us 

 a difference of less than 1 percent in favor of the spring spraying, and 

 the ratios of plots 9 and 13, treated with Target Brand, show a differ- 

 ence of less than 3 percent in favor of that insecticide. This is in 

 accord with the general opinion that a spring spraying with lime- 



