18 CONTROL OF PEACH BROWN-ROT AND SCAB. 



spra} r ed twice. The check plat, which lies between plats 1 and 2, 

 certainly represents something near the average conditions for the 

 whole block involved and the difference in yield between the sprayed 

 and the uhsprayed trees was, for the most part, undoubtedly due 

 to the effect of the spraying. The application of self-boiled lime- 

 sulphur, therefore, apparently increased the yield by 100 per cent. 



SELF-BOILED LIME-SULPHUR AND ARSENATE OF LEAD IN COMBINATION. 



It has been known for many years that the curculio is an important 

 factor in the distribution of brown-rot and that to prevent the former 

 would be an important step toward controlling the latter. In our 

 first lime-sulphur experiments during 1907 the interference of this 

 insect with the efficacy of spraying for the control of brown-rot was 

 again clearly brought out. In discussing the results of that year's 

 work the senior writer stated that "the plum curculio punctures the 

 skin of a certain percentage of the fruit and admits the fungus in 

 spite of all spraying that can be done." ° Although in most of our 

 experiments the brown-rot has been held down by spraying to about 

 10 to 15 per cent where the unsprayed fruit ran 50 to 70 per cent of 

 brown-rot, it has nevertheless been apparent in all the work that 

 spraying for brown-rot would not be entirely satisfactory so long as 

 the curculio was not also controlled. 



Entomologists have known for many years that the curculio could 

 be controlled by the application of arsenical poisons, but owing to the 

 danger of injury to both fruit and foliage they have very properly 

 been cautious about recommending their use on peach trees. Mr. A. 

 L. Quaintance, of the Bureau of Entomology, during the past five or 

 six years, has experimented extensively on the use of arsenate of 

 lead for spraying peach trees, with the result that a high percentage 

 of curculio injury was always prevented by two or three sprayings 

 beginning soon after the petals dropped. In 1905 he recommended 

 with due caution the spraying of peach trees with arsenate of lead for 

 the control of this insect. 6 Mr. E. P. Taylor, c of the Missouri Fruit 

 Experiment Station, recently reported that during 1908 he had 

 obtained a high percentage of fruit free from curculio by the use of 

 arsenate of lead, with very little injury to the foliage. He also noted 

 a very marked reduction of brown-rot on the sprayed trees. 



In order to test the practicability of combining arsenate of lead 

 with self-boiled lime-sulphur as a combination treatment for scab, 

 brown-rot, and curculio, one of our principal experiment blocks at 

 Fort Valley, Ga., was devoted to this purpose. This work was car- 

 et Circular 1, Bureau of Plant Industry. U. S. Dept. of Agriculture, 1908, p. 1(5. 

 b Yearbook, U. S. Dept. of Agriculture, for 1905, p. 329. 

 c Journal of Economic Entomology, vol. 2, 1909, p. 156. 

 174 



