528 ANNUAL, REPORTS OF DEPARTMENT OF AGRICULTURE. 



of arsenic in the soil, and an examination also of trees which might 

 be injured from this cause. A large number of samples was collected 

 during the summer of 1900, and these have been examined by the 

 Bureau of Chemistry, in cooperation with which Bureau the work 

 is being done. The examination of these soils has shown the neces- 

 sity for further studies and an additional series of soil samples will 

 be collected from the same territory as those earlier obtained. 



INSECTICIDE INVESTIGATIONS. 



Further experiments have been made with lime-sulphur washes, 

 especially when used with various arsenicals. Special attention is 

 being given to determine the effects of a combined lime-sulphur and 

 arsenical spray on peach foliage, including the various brands of 

 arsenate of lead and other poisons, such as arsenic sulphids, arsenate 

 of iron, zinc arsenate, etc. In California much attention has been 

 given to the preparation of various sprays, especially emulsions of 

 crude oil and distillate, in the course of experiments against the 

 European pear scale and the European fruit Lecanium, or, as it 

 is better known, the brown apricot scale. 



DEMONSTRATION SPRAYING FOB THE PLUM CURCULIO. 



The plum curculio in the South is a veritable scourge to the peach 

 growers, every year greatly curtailing the crop, its punctures in the 

 fruit, moreover, forming a nidus for brown-rot spores, greatly favor- 

 ing infection from this serious fruit disease. So critical had become 

 the situation due to the losses from these two troubles — the curculio 

 and the brown rot — that the assistance of the Department was asked 

 through the Georgia Fruit Growers' Exchange, and also by numerous 

 large commercial orchardists. In cooperation with the Bureau of 

 Plant Industry, demonstration spraying on a large scale was be^n 

 in different parts of Georgia, using arsenate of lead and self-boiled 

 lime-sulphur mixture as a combined treatment for the curculio and 

 brown rot and the scab. The scheme of treatment requires three 

 applications in all, which practice it had previously been determined 

 would effect the control of the several troubles. In addition to the 

 work under the direct supervision of the Department a very large 

 number of orchardists, acting under its advice, has adopted the plan 

 of spraying recommended, and the total trees treated during the 

 spring of 1910 aggregated several hundred thousands. This work 

 is conducted on a strictly commercial basis, careful account being 

 kept of the cost of the work, and the benefits will be accurately 

 determined by a comparison of the fruit on sprayed and unsprayed 

 blocks. 



CRANBERRY INSECT INVESTIGATIONS. 



Th§ studies of cranberry insects in Wisconsin, in cooperation with 

 the university of that State, mentioned in earlier reports, were con- 

 tinued along the lines indicated during the season of 1909, and be- 

 ginning with the spring of 1910 demonstration spraying has been in- 

 augurated in cooperation with numerous cranberry growers, who 

 bear all costs of the work except for spray materials. An unusually 



