44 Bulletin 332 



order to kill all the eggs of A. avenw. Eggs of A. pomi and A. 

 sorbi also respond in a similar manner to combinations of "Scale- 

 cide" and crude carbolic acid; however, they are apparently some- 

 what more resistant, and consequently more will hatch. 



In the orchard ''Scalecide" 1-15 was given a trial at John H. 

 Barclay's place in 1917 in conjunction with a combined spray of 

 lime-sulfur 1-9 and "Black-leaf 40" 1-500. During the morning 

 of April 7, Mr. Barclay sprayed 100 large apple trees with ' ' Scale- 

 cide" 1-15. The buds were swollen and some of the leaves were 

 out about }i inch. These trees at the time of spraying averaged 

 five nymphs of A. avenm per bud. A careful examination was 

 made of several hundred buds at 5 o'clock the afternoon of the 

 same day, and at this time the nymphs averaged 1 living aphid to 

 25 buds; in other words, the "Scalecide" killed 99 per cent of the 

 nymphs. These trees were again examined on April 14 when the 

 leaves were out ^ to ^ inch long, and at this time the nymphs 

 averaged one to every two buds, but these were mostly nymphs of 

 A. sorhi. Out-of-door laboratory experiments conducted during this 

 period showed that all eggs of A. avenm had hatched by April 6 or 7, 

 and the eggs of A. sorhi commenced to hatch about April 12. Accord- 

 ing to these data the eggs of A. sorhi hatched after April 7, and 

 "Scalecide" did not prevent all the eggs of this species from 

 hatching. In fact, the infestation was severe enough to demand 

 the use of "Black-leaf 40" 1-500 when the lime-sulfur 1-40 was 

 applied at the pink-bud stage. Even though this measure of pre- 

 caution was taken the results were by no means satisfactory. 



In contrast to the above experiment, lime-sulfur 1-9 plus 

 "Black-leaf 40" 1-500 was applied to about one hundred infested 

 trees (5 nymphs to the bud) on April 7, and an examination made 

 in the afternoon of the same day showed that so many of the 

 nymphs had been killed that none could be found. A vast ma- 

 jority of the eggs of A. sorhi. also were killed, for no nymphs could 

 be found on April 14 ; however, a very few did survive, for in the 

 latter part of IMay and in June an occasional tree showed a few 

 clusters of leaves infested with A. sorhi, but the majority of the 

 trees were entirely clean. The trees treated with "Scalecide" on 

 April 7 and later sprayed with lime-sulfur 1-40 plus "Black-leaf 

 40" showed during May and June a comparatively heavy infesta- 

 tion. No tree was completely free and in many a considerable 

 amount of fruit was damaged. One tree which had received no 

 dormant treatment or nicotine sulfate served as a check, and this 

 tree was severelj^ infested, over 75 per cent of the leaves being 

 badly curled and a large percentage of the fruit ruined. These 

 experiments, along with those conducted at the laboratory, show 

 the superiority of lime-sulfur 1-8 or 1-9, plus "Black-leaf 40" 



