INSECTS, DISEASES, AND INJURIES 157 



From what has been said it is evident that the removal of 

 all Ribes plants, both wild and cultivated, from the vicinity 

 of white pines will ensure against infection. This removal 

 must be thorough and, under normal conditions, should be 

 carried out within a radius of 200 to 300 yards. 



In the case of valuable ornamental white pines which are 

 already infected, experiments have shown that the removal 

 of infected parts is financially practicable if the treatment is 

 applied in time, and is carried out in conjunction with the 

 eradication of Ribes. The best results will be obtained if the 

 work is done from April to June when the cankers are more 

 easily found because of the bright orange-yellow blisters. 

 The workmen must be thoroughly familiar with the disease, 

 as the success of the treatment depends on the finding of all 

 cankers and the accurate determination of the edge of the 

 diseased area. Diseased twigs and branches should be cut 

 off seven or more inches back of the orange-yellow blisters. 

 If none of these is present, the branches should be cut off 

 five or more inches back of the extreme edge of the canker 

 and flush with the next whorl of healthy branches. On large 

 limbs and trunks, infections which have not passed completely 

 round may be treated by removing all the diseased bark and a 

 strip at least two inches wide at the sides and four inches at 

 the ends of the apparently healthy bark from around the edge 

 of the canker. Large wounds should be protected from the 

 attacks of other fungi and insects by a covering of shellac and 

 bark-colored paint. If the tree is nearly girdled, or if most 

 of the branches must be removed, it is useless to attempt to 

 save it.*' j 



* Spaulding, P. Investigations of the White Pine Blister Rust. U. S. Dept. Agr. 

 Bull. 957 : 1-100. 1922. 



t Martin, J. F. et al. Treatment of Ornamental White Pines infected with Blis- 

 ter Rust. U. S. Dept. Agr. Circ. 177 : 1-20. 1921. 



