﻿14 



BULLETIN 1311, TJ. S, DEPABTMENT OF AGRICULTURE 



From these observations it was thought that there might be a 

 difference in the efficacy of the products on account of the fact that 

 the polysulphide sulphur in the dry hme-sulphur was not in as high a 

 ratio to the polysulphide calcium as the polysulphide sulphur to polysul- 

 phide calcium in the lime-sulphur solution. 



With this in mind, solutions were prepared having the same 

 molecular ratio of sulphur andlime as calcium trisulphide, calcium tetra- 

 sulphide, and calcium pentasulphide. These solutions were diluted so 

 that the total polysulphide content, when apphed as a spray, was the 

 same as the total polysulphide content of the hme-sulphur solution 

 and dry lime-sulphur when apphed as sprays. Calcium thiosulphate, 

 calcium sulphite, and sulphur were also prepared and tested. 



The essential materials used and the results of these experiments 

 are shown in Table 10. 



Table 10. — -Effectiveness of the ingredients of dry and liquid lime-sulphur used 

 in experiments against the San Jose scale 



Ex- 

 peri- 

 ment 

 No. 



2 

 3 



4 

 5 

 6 



27 

 28 



9 



no 



11 



<12 

 13 

 14 

 15 

 16 

 17 

 18 

 19 



Material used 



Liquid lime-sulphur (32 per cent calcium poly- 

 sulphide). 

 Same, with 1.11 pounds of sugar to 50 gallons. 

 Same, with 10 pounds of sugar to 50 gallons... 



Liquid lime-sulphur A 



Same, with l.ll pounds of sugar to 50 gallons. 



Dry lime-sulphur A 



do 



Same with all sludge removed 



Calcium pentasulphide (CaSs) ^ 



do 



Calcium tetrasulphide (CaSJ ' 



do 



Calcium trisulphide (CaSs) ^ 



Calcium thiosulphate 



do 



Calcium sulphite 



do 



Sulphur 



Check, untreated 



Dilution 



6.66 gallons to 50 gallons. 



.do. 

 -do. 



Equivalent to No. 1 1. 



do 



do 



do 



do 



do 



do 



do. 



do 



do 



1 ounce to 1 gallon 



24 ounces to 1 gallon... 



H ounce to 1 gallon 



12 ounces to 1 gallon... 

 Equivalent to No. 1 L 



Dead 



Per cent 

 95.95 



95.90 



93.00 



89.75 



88.00 



50.40 



59.0 



96.0 



93.10 



95.20 



89.5 



93.5 



43.4 



13.4 



18.45 



19.37 



16.55 



19.45 



19.25 



Control 



Per cent 

 94.98 



94.92 

 91.33 

 87.30 

 85.14 

 38.58 

 35.94 

 93.75 

 91.46 

 94.27 

 87.00 

 92.24 

 29.91 









 .15 





 .25 



1 Based on polysulphide-sulphur content. 



2 Check, 36 per cent dead. 



' Calcium polysulphides are so prepared that the molecular ratio of calcium to sulphur equals 1 to 5, 1 to 

 4, and 1 to 3, respectively. 

 * 1923 experiments; check, 16.2 per cent dead. 



With the exception of Nos. 7, 8, 10, and 12, the experiments con- 

 sidered in Table 10 were carried on in a moderately infested peach 

 orchard in Opehka, Ala. A dormant apphcation was made on 

 January 28 and 29, using a wheelbarrow sprayer having a vertical 

 agitator and maintaining a pressure of about 100 pounds. The 

 counts of hibernating scales were made on March 7, 8, 9, and 10. 



Experiments 7 and 8 were made on small, badly infested peach 

 trees near Vienna, Va. The sprays were applied with a knapsack 

 sprayer on March 17 and the scale count was made on April 17. 



Experiments 10 and 12 were a part of the 1923 series on apple 

 trees, the details of which are given on pages 11 and 12. 



Experiments 2, 3, and 5 mentioned in Table 10, which were made 

 with liquid hme-sulphur and granulated sugar, indicate that the 



