86 MASS. EXPERIMENT STATION BULLETIN 347 



Mcintosh that are held for a short period at 45° F. after harvest before being 

 cooled to 32° F. develop a better flavor than simikr apples held at 32° F. con- 

 tinuously, and will hold in marketable condition until January 1 or later. A 

 repetition of this work during the past season confirms the results of previous 

 years. 



Tests of Various Spray Materials. (O. C. Roberts cooperating with Depart- 

 ments of Entomology and Botany.) This project of testing spray materials was 

 continued during the past season. Each year a multitude of new materials appear 

 on the market together with various recommendations, chiefly by manufacturers, 

 for the mixing and combining of established preparations. These numerous 

 possibilities tend to confuse rather than assist the fruit grower. Hence, the purpose 

 of these spray tests each year is an attempt to measure the real worth of those 

 materials and combinations which appear to merit consideration. A discussion 

 of the materials tested this year together with results obtained may be found in 

 the report of the Entomology Department. 



Elimination of Arsenic and Lead Residues from Apples. (O. C. Roberts co- 

 operating with Entomology Department and Fertilizer Control Service.) Since 

 1925 when the Federal Government placed a limit of tolerance for arsenic on 

 apples, the fruit-growing industry has been concerned with the elimination of 

 residue. Results of previous work at this Station have shown that adherence to 

 the recommended spray schedule for Massachusetts will produce fruit that is 

 practically free from insect and disease blemishes and at the same time is within 

 the limits of tolerance of .018 gr. per pound for lead and .01 gr. As.,03 per pound 

 for arsenic. With the possible reduction of the tolerance for lead it is conceivable 

 that the present spray schedule might leave deposits of lead in excess of the lower 

 tolerance. With this possibility in mind experiments on methods of removal were 

 begun in 1934. This work has been continued this year with Mcintosh and Cort 

 land apples which received a complete spray schedule. Several bushels of each 

 variety were wiped on a commercial wiper and similar lots of each were washed 

 in a one percent solution of hydrochloric acid. Samples were taken from each lot 

 before and after treatment and were analyzed for lead and arsenic residues by the 

 Fertilizer Control Service. The results of the analyses are shown in the follow- 

 ing table. 



McINTOSH CORTLAND 



Arsenic Arsenic 



Lead (As.Oj) Lead (As.Oi) 



Untreated... .009 .0033 .019 .0065 



Wiped Oil .0044 .021 .01144 



Washed 003 .002 .002 .00077 



These results are consistent with those obtained in previous work at this 

 Station, and show that wiping tends to increase the arsenic and lead residues 

 rather than decrease them and that washing in a one percent solution of hydro- 

 chloric acid is an effective method of reducing these residues well within the 

 limits of tolerance. 



The Nutrition of the Highbush Blueberry, Especially in Relation to Soil Reac- 

 tion. (J. S. Bailey.) Blueberry Plot D which is to be used in connection with the 

 nutrition work, bore its first crop in 1937. The experiments started in 1936 to 

 test various chemicals as acidifiers for blueberry soil were continued in 1937. 

 On May 21 one gram of nitrate of soda was added to each plant. This fertilizer 

 greatly increased the growth of the plants but at the end of the season the relative 



