REPORT OF THE SECRETARY OF AGRICULTURE. 45 



corn borer occupies a large part of the peninsula bordered by Lakes 

 Ontario, Erie, and Huron, Another parasitic species which first 

 was liberated in Massachusetts in the fall of 1922 has been recovered 

 from the field in several different localities in New England, and the 

 establishment of this species there seems now assured. There were 

 no developments of great importance in the corn borer situation 

 during the past year. 



Study of calcium arsenate dusting methods for checking cotton 

 boll weevil infestation showed that some success has been achieved 

 by this means. Severe weevil infestation in 1922 caused a more ex- 

 tensive use of calcium arsenate than ever before, and a shortage of 

 this material developed. A special investigation was made of the 

 results secured by approximately 1,100 farmers who dusted al- 

 together 125,485 acres of cotton. These farms were quite uniformly 

 distributed over practically all of the Cotton States. Slightly more 

 than 96 per cent of the farmers using calcium arsenate were success- 

 ful in controlling the weevil to the extent of making the operation 

 profitable. The average increase in yield upon these farms was 339 

 pounds of seed cotton per acre. Special studies were conducted to 

 determine the minimum yield per acre on land where dusting with 

 'calcium arsenate would be justified by the results obtained. It was 

 found that in general the season's dusting on any particular farm 

 should cost not to exceed the current value of 100 pounds of seed 

 cotton per acre in order to make a profit by the dusting method, 



BL.ACK STEM RUST OF" WHEAT. 



The barberry eradication campaign, the objective of which is the 

 control of the black stem rust of wheat and other cereals through the 

 eradication of the common barberry, which is the intermediate host 

 of this destructive fungus disease, has been systematically prosecuted 

 during the year in 13 States of the Mississippi Valley and the Great 

 Plains region, where it was begun in the spring of 1918. The initial 

 survey has been completed in Wyoming, and but few counties remain 

 to be covered in Colorado and Montana. During the entire campaign 

 more than five and three-quarters million bushes have been located 

 on more than 55,000 properties. These are destroyed by thorough 

 uprooting or by the application of common salt or diluted sodium 

 arsenite where the conditions render these materials practicable and 

 safe. 



