38 Bulletin 332 



than a week or more than ten days. In using a combination spray 

 it would be better to apply the material thoroughly somewhat early 

 than to wait too long, for as a ru.le weather conditions are very 

 changeable during the latter part of March. 



Other workers have had some experience with the combination 

 spray. Wilson (24) in 1912 recommended for A. pomi and A. 

 sorbi: "Spray in the spring just as the buds are opening with 

 lime-sulfur plus 'Black-leaf 40' or 'Black-leaf 40' alone. Spray 

 thoroughly applied at the time when the buds are opening will 

 prevent 95-100 per cent of the aphis infestation. The lime-sulfur 

 should be used winter-strength and the 'Black-leaf 40' added at the 

 rate of 1 part to 900 parts of diluted lime-sulfur". Mr. Wilson 

 does not indicate in his experiments wlu^her the eggs have all 

 hatched or not. In either case the eom])ination will undoubtedly 

 succeed, but nicotine sulfate alone at the strength of 1-900 would 

 not kill many of the eggs, according to our experience. 



During the spring of 1916 a number of experiments were con- 

 ducted in various orchards in the state of New York by P. J. 

 Parrott, H. E. Ilodgkiss and F. H. Lathrop (18) with the use of 

 lime-sulfur 1-8 plus ^ pint of nicotine solution (40 per cent) to 

 100 gallons of solution. In these experiments, "the s])raying was 

 purposely delayed until the eggs had begun to hatch and it is 

 reasonably certain that most of the nymphs had emerged." The 

 results obtained in the various orchards were altogether satisfactory 

 and they agree in large measure with those secured by various 

 orchardists throughout New Jersey. The principal difference, how- 

 ever, is the fact that the eggs of A. sorM had not started to hatch 

 Avhen the material was applied April 8. 1917, at iMr. Barclay's 

 orchard ; nevertheless they were killed. In the various experiments 

 conducted in New York it is possible that some of the eggs had not 

 hatched, for according to the authors ' own statement they were only 

 "reasonably certain that most of the nymphs had emerged." It 

 may be possible to delay the "dormant spray" in New York or- 

 chards until the eggs of all species are hatched, but this is not the 

 case in New Jersej^ for the eggs of A. pomi and A. sorhi in two 

 successive seasons, 1916 and 1917, did not hatch to any extent 

 until the leaf buds had burst and the small leaves were well sepa- 

 rated. 



Dr. T. J. Ileadlee (9, 10) in 1916 carried on an extensive series 

 of experiments against the rosy aphis at John H. Barclay's orchard 

 and a brief summary of his data shows that the rosy aphis can best 

 be destroyed by making a dormant treatment with lime-sulfur and 

 followiug that with a green-bud treatment of "Black-leaf 40" 

 (1-1000) plus soap (2 pounds to 50 gal.), or by delaying the dor- 

 mant treatment of lime-sulfur until the buds begin to show green, 

 and then applying it mixed with "Black-leaf 40" (1-500). These 



