58 PROTECTION OF PLANTS, 1917-18 



THE CONTROL OF THE WHITE-MARKED TUSSOCK MOTH. 



By J. M. Swaine, In charge of Forest Insect Investigation, Entomological 



Branch, Ottawa. 



The shade trees of our cities and towns form an asset of enormous value. The 

 beauty of their fohage and the comfort afforded by their shade help to render our 

 cities habitable during the hot summer months. 



Their value is partly expressed in money in the increased property values. 

 Real estate dealers have estimated the increased property value due to trees on and 

 near residence property at 40% to 100%. Large and fine trees have been valued 

 by competent authorities at from $150 to $500. If the shade trees were entirely 

 removed from a good resident street in Montreal, how would property values on 

 the street be affected? Without any question our city shade trees form an asset 

 worth many hundreds of thousands of dollars, and it is plainly worth while to 

 spend a few thousand dollars in their protection when this is needed. It is un- 

 fortunate that our shade trees have been almost entirely neglected in many places 

 until the greater part of them are more or less seriously weakened by boring in- 

 sects and fungous diseases, and are defoliated by periodic outbreaks of leaf-feeding 

 caterpillars. 



In addition to the danger from their insect and fungous enemies the trees 

 have to contend with extremely adverse soil conditions and atmospheric conditions 

 as well as with breakage from wind and ice. Protection against breakage is 

 largely insured by a proper support of bolts and chains. 



The control of fungous diseases consists chiefly in excavating all the decayed 

 wood, disinfecting with creosote the clean wood surface thus exposed, and filling 

 the cavity with cement. Scars from pruning or any other cause should be disin- 

 fected with creosote and coated with tar, leaving the cut edge of the bark and 

 cambium clean. All dying and dead trees and parts of trees should be removed 

 and burned early in the season before the insects and fungi which they contain can 

 spread to other trees. 



The most serious insect injuries to shade trees are caused by boring grubs or 

 caterpillars and leaf-feeding caterpillars, grubs and saw-fly larvae. 



The most effective general measure against large wood-boring larvae is to cut 

 out and destroy the young borers with a sharp knife and a wire, or to kill them 

 within their burrows by injecting therein carbon-bisulphide from a small syringe 

 and closing the openingjwith putty, soap or clay. After twenty-four hours the 

 dead larvae should be removed if possible, the cavities disinfected, and then filled 

 with cement or putty. 



