REPORT OF THE SECRETARY OF AGRICULTURE. 23 



■were located there, and also because they could be most easily and 

 cheaply reached. In a farm-to-farm survey, which has been in 

 steady progress during the last three summer seasons, 447 counties 

 have been covered by squads of field men. It is estimated that it 

 will be necessary to survey about 800 counties in all. More than five 

 and one-half million barberry bushes have been found and destroj^ed. 

 The magnitude of the task has grown as we got into it. Barberry 

 bushes are found growing wild here and there, and especially in the 

 timbered portions of the States bordering on the Mississippi River. 

 The complete eradication of the bushes when they are found is 

 more difficult than had been supposed. If portions of the roots are 

 left in the soil sprouts may develop under favorable conditions. 

 This makes resurveys necessary and adds much to the duration and 

 ^expense of the campaign. Many bushes are found in broken or 

 rocky ground where it is impossible to remove the roots. Experi- 

 ments in the use of chemicals as destructive agents are being made 

 and seem to offer promise. With continued appropriations and co- 

 operation on the part of interested parties, it is believed that the 

 campaign against the barberry can be rapidly carried to a success- 

 ful conclusion. 



WHITE-PINE BLISTER RUST. 



The white-pine blister rust, which has been destructive in some of 

 the New England forests and has been mentioned in previous reports, 

 has been found at points in the northwestern forests. A quarantine 

 was promptly established, and by the vigorous application of methods 

 of control which have worked successfully in the New England for- 

 ests it is hoped to promptly check the spread of the disease. This 

 disease is spread somewhat after the manner of the rust of wheat, 

 the intermediate hosts being currant and gooseberry bushes. 



PREDATORY ANIMALS AND RODENT PESTS. 



Similar to the warfare against plant and animal diseases and in- 

 sect pests is the struggle to control or eradicate predatory animals 

 and rodent pests. The annual loss to agriculture from injurious 

 rodents has been estimated to exceed $500,000,000. This has been 

 materially reduced through the campaigns led by the scientists of 

 the department, which have destroyed most of the rodents on almost 

 100,000.000 acres of public and private land. The destruction of 

 25684— AGR 1923 3 



