THE EUROPEAN ELM SCALE IN" THE WEST. 17 



A more satisfactory method of control is the use of miscible oil 

 containing 23° to 28° Baume oil, which can be obtained from dealers 

 under various trade names. This should be used in the following 

 proportions : 



Miscible oil (23° to 28° Baume) 1 gallon or 16 gallons. 



Water 12 gallons or 184 gallons. 



It is mixed by first pouring the requisite amount of oil into the 

 spray bucket, barrel, or tank to be used and then adding a small 

 amount of water. With considerable agitation this will become light- 

 colored and of a creamy consistency, whereupon more water may be 

 added, and finally all the water, in the meantime agitating thor- 

 oughly. This may then be applied with any sort of spray outfit, 

 providing the apparatus has power enough to send a spray to the 

 tree tops. 



The bucket or barrel pump will do very well for small trees, the 

 ordinary orchard power outfit for trees up to 40 feet in height, and a 

 high-power apparatus for trees above this height. (Fig. 6.) A 

 pump registering a pressure of at least 300 pounds with a capacity 

 of 12 to 15 gallons or more per minute is necessary to reach trees 60 

 to 90 feet high, which is often the height of mature elms. A spray 

 gun or solid-stream Worthley nozzle is necessary to force the spray 

 to the tops of the trees from the ground. The use of a smaller outfit 

 and ladders is not to be recommended, on account of extra cost and 

 unsatisfactory results. 



Large trees require from 30 to 50 gallons of mixture, costing from 

 3 to 4 cents per diluted gallon for the material and 1-| to 2-J cents per 

 ,gallon to apply it. 



Every branch and twig should be covered, but too much spray 

 should not be allowed to settle about the base of the tree, as it might 

 injure the roots. No damage to elm trees or lawns has been noted, 

 however. 



The spraying should be done in the winter up to the time the 

 buds begin to open in the spring. Probably a weaker spray could 

 be used on the young forms in the late summer but this would be 

 about as expensive, for nearly twice the amount of material would 

 be required to cover each tree on account of the foliage, and it 

 would be much less satisfactory since all parts, particularly the 

 underside of the leaves, which are the most heavily infested, could 

 not be thoroughly covered. 



If properly done, spraying should not be necessary every year, 

 except upon young trees, which seem to become reinfested easily 

 when near unsprayed large trees. Extermination, of course, is not 

 to be hoped for, but it is possible to kill a sufficiently high percent- 

 age of the insects to prevent their appearance in large numbers the 

 following season. 



SUMMARY. 



The European elm scale was introduced into this country about 

 1884 from Europe and was first found at Eye, N. Y. From there 

 it has spread until it is now located in 27 States and the District of 

 Columbia. Although more widespread in the East, the injury to 



69577°— 24 2 



