16 The Eubopean Elm Scale 



The American Elm, (White Elm, JJlmus Americana, Linnaeus). 



Of a taller, more slender, and more graceful habit of growth than 

 the English Elm. The bark is of a lighter grey color and is devoid of 

 cork. Some specimens branch almost as diffusely as the English Elm, 

 although the general habit of growth is never so stocky and the indi- 

 vidual branches are lighter and more slender. Many of these Amer- 

 ican elms are already tall and elegant trees, fifty feet in height, with 

 long, sweeping branches.. They are apt, however, to be somewhat mis- 

 shapen and unsymmetrical because of their greater height and conse- 

 quent exposure to the full sweep of the wind. In this region the 

 American Elm is apt to be more seriously injured by the European 

 Elm Scale than is the English Elm. While the bark is smoother it is 

 apt to be full of cRacks and crevices, which offer much protection to 

 the hibernating larvae. On the whole, it is a much less sturdy and 

 hardy tree than the English Elm and is much more subject to insect 

 attacks. 



LIMB-SULPHUR AS A REMEDY FOR THE EUROPEAN 

 ELM SCALE 



As the preparation and use of this insecticide is understood by 

 nurserymen and others who do commercial spraying in this vicinity, 

 and as it is the recognized standard remedy for the San Jose Scale, 

 I sprayed a number of elms with it in February, 1907, to see whether 

 it would also check Gossyparia spuria. 



FORMULA 



Lime 20 lbs. 



Sulphur 15 lbs. 



Water 50 gals. 



The lime-sulphur mixture was boiled with steam from a traction 

 engine for two hours or more in about thirty gallons of water, twenty 

 gallons more were then added and the mixture used while still warm. 

 The trees were sprayed with the greatest care ; we aimed to wet every 

 inch of bark on the tree from the smallest twigs down to the ground. 

 At first we did not succeed in this entirely ; for it is far more difficult 

 to spray a cork elm than an apple tree of the same size. If any large 

 portion of the hibernating larvae are to be reached, the bark between 

 the projecting ridges of cork must be soaking wet with the spraying 

 mixture. In this we failed at first. A careful inspection of the sprayed 

 trees showed many spots that had not been covered at all. All such 

 spots were sprayed a second time, and several of the trees were thor- 



