October, '19] PETERSON: APHID EGGS 375 



Barium sulfur, largely barium tetra sulphide, commercially known 

 as "B. T. S." was given the same liquid spray tests as dry lime-sulfur 

 (Tables I and II and Charts II, III and V). Where "B. T. S." was 

 used at the rate of 15 pounds to 50 gallons, the killing or efficiency 

 (eggs of A. avence) is somewhat superior to that of coarse dry lime- 

 sulfur at the same strength, but is decidedly inferior to concentrated 

 hquid lime-sulfur, 1-9 (Charts II and V, fine h). "B. T. S." 20 

 pounds to 50 gallons comes nearer being equal to concentrated liquid 

 lime-sulfur. "B. T. S." is highly soluble in water, 98.1 per cent at 

 the recommended winter strength of 14 pounds to 50 gallons of water. 

 The sulfur content per gallon of the recommended dormant spray of 

 "B. T. S." as it goes on the tree is approximately 50 per cent that of 

 concentrated liquid lime-sulfur, 1-9. 



Sodium-sulfur, largely sodium polysulphide, commercially known as 

 "Soluble Sulphur," was experimented with at the rate of 15 pounds 

 to 50 gallons of water. This dry substitute for concentrated lime- 

 sulfur proved to be the most efficient in killing the eggs of A. avence, 

 yet in no instance did it equal that of concentrated liquid lime-sulfur," 

 1-9 except on March 21, 1919, when its efficiency was approximately 

 the same (Chart II and V, line i). "Soluble Sulphur" is very caustic 

 and also highly soluble (98.5 per cent soluble) at the rate of 14 pounds 

 to 50 gallons of water. A quantative analysis of the recommended 

 dormant strength of "soluble sulfur" as it goes on the tree shows 

 approximately 50 per cent as much sulfur per gallon as concentrated 

 liquid lime-sulfur, 1-9. 



Nicotine 



In all the spraying experiments with the eggs of A. avence and A. 

 pomi, the addition of nicotine always increased the killing efficiency 

 of every spray. This is particularly true when nicotine, 1-500 was 

 added to concentrated liquid lime-sulfur, 1-6 or 1-9 (j, k, 1 and m, 

 Chart III), to dry (coarse or dust form) lime-sulfur, 10, 15 or 20 pounds 

 to 50 gallons (n and o. Chart III), to barium-sulfur ("B. T. S."), 10, 

 15 and 20 pounds to 50 gallons (p. Chart III), and to sodium-sulfur 

 ("Soluble sulphur"), 15 pounds to 50 gallons (q, Chart III). Chart 

 III shows the results of a series of experiments with one or more 

 strengths of each of the above substances plus nicotine, 1-500. Com- 

 paring Chart II with Chart III spray lines a = j, b = k, c = l, d = m, 

 e = n, g = o, h = p, and i = q, except for the addition of nicotine 1-500 

 in j, k, 1, m, n, o, p, and q. All of the experiments seen on Chart III 

 show a percentage of kill running between 97 and 100 per cent when 

 the combined spray is applied on March 1, March 10, and Mardi 21. 

 On these same dates all of the concentrated liquid lime-sulfur sprays 



