50 BULLETIN 395, U. S. DEPARTMENT OF AGRICULTURE. 



This orchard, which had been practically abandoned, had just been bought for 

 planting to applea. It •was chosen as offering most adverse conditions for the produc- 

 tion of good fruit and a most severe test of the efficacy of the treatments used. 



Plats 9-i5.— Vigorous, well-grown, well-kept, 8-year-old Elberta trees. Orchard 

 elevated and slightly rolling, with excellent air and surface drainage. Sandy clay 

 soil. Had received a winter application of lime-sulphur. Well pruned, cultivated, 

 and fertilized. Crop good. 



Plats 16-22. — Vigorous, 8-year-old Belle trees, well kept, but slightly under size. 

 Sandy clay soil. Orchard elevated and slightly rolling, with good air and surface 

 drainage. Had received the winter application of lime-sulphur. Well pruned, cul- 

 tivated, and fertilized. Crop good. 



RESULTS ON FOLIAGE. 



Observations made at frequent intervals throughout the season 

 showed no evidence of spray injury upon any of the plats treated 

 with self -boiled hme-sulphur. In plats 9, 9A, 9B, and 11, however, 

 sprayed with the sulphur paste and arsenate of lead, a considerable 

 amount of "shot-holing" and yellowing of the fohage began to appear 

 about the middle of July. This was followed by some defohatioh 

 throughout late July and early August. The fruit of these plats was 

 very highly colored but not injured. The foliage of the parallel 

 self-boiled lime-sulphur plats (12, 13, and 14) was not injured, being 

 quite vigorous, well colored, and free from disease except for a limited 

 amount of leaf injury which possessed the typical characteristics of 

 peach bacteriosis {Bacterium pruni Smith). The fohage of the con- 

 trol plat, though less vigorous than that of plats 12, 13, and 14 and 

 not so well colored, showed very little yellowing and defohation. 

 These facts strongly suggested that the trouble in plats 9, 9A, 9B, 

 and 11 was some type of spray injury. 



Inasmuch as each of the earher treatments had been omitted from 

 one or another of plats 9 to 15, conclusive data appear to be available. 

 The key to the situation seems to lie in plat 10, which was treated 

 in the same manner as the adjacent plats, 9 and 9A, except that the 

 second apphcation was omitted. On this plat, directly adjacent to 

 plat 9, the fohage went through the season in excellent condition, 

 closely approaching that of the self-boiled lime-sulphur plats in vigor 

 and color. Thus, all plats (9, 9A, 9B, and 11) which received the 

 sulphur paste and arsenate of lead in the second apphcation were 

 generally affected, while none of the remaining plats showed any 

 evidence of spray injury. Therefore, it seems conclusive that the 

 injury must have resulted from this treatment. 



No experiments were made to test separately and comparatively 

 the action of the sulphur paste and of arsenate of lead. However, 

 since sulphur alone has proved to be one of the safest fungicides 

 known and since the sulphur paste caused no injury when applied 

 alone in the tldrd treatment on plat 10, it seems evident that the 



