THE POPLAR AND WILLOW BORER 479 



Method of application of carbolineum 



After many trials it was found that the simplest method of application 

 of carbolineum was by the use of cotton waste. Carbolineum is non- 

 injurious to the hands, and each workman carried a small quantity of 

 the material in a dipper or a tin can. The cotton waste was dipped 

 into the material and then rubbed carefully up and down the trunk of 

 the tree. It is usually not necessary to go higher than four or five feet, 

 but great care should be exercised to see that the base of the tree is well 

 treated and all parts of the trunk are well covered. At the same time 

 the material should not be allowed to run down to the roots. After the 

 trees are pruned workmen can apply the material at a very rapid rate. 



It is preferable to make the application on a warm day, as under this 

 condition the carbolineum is thinner and may be more easily applied. 



Cost of treatment 



It was at first thought that the cost of the treatment might prevent 

 its use under nursery conditions, inasmuch as poplars are not very high- 

 priced stock. In one nursery a careful account of the entire cost of 

 treatment was kept. This was as follows: 



Labor, treating 14,000 trees $18 . 50 



Carbolineum, 7 gallons at 90 cents 6 . 30 



Total cost $24.80 



Total cost per tree $0.00177 



It is thus seen that the cost per tree is extremely small, not exceeding 

 two-tenths of a cent a practically negligible charge. 



SUMMARY 



The poplar and willow borer is a European pest recently introduced 

 into America and at present widely distributed in the northeastern United 

 States. It is proving a serious pest not only in nurseries but also wherever 

 willows or poplars are grown. 



A very effective means for control of the insect is the use of carbolineum 

 avenarius. In nurseries this should be applied by hand during the latter 

 part of March or the first week in April. The work can be done most 

 advantageously just after the trees are pruned. 



In setting out poplar trees they should be treated with carbolineum 

 in order to insure the destruction of all larvae present. This can be done 

 either in the fall or in the spring while the trees are dormant. 



The item of cost has been shown to be extremely small, not exceeding 

 two-tenths of a cent per tree under nursery conditions. 



