THE EUROPEAN ELM SCALE IN THE WEST. ~-- -13 
CONTROL EXPERIMENTS. 
. TABLE 1.—Haperiments performed upon the European elm seale. 
Date. Spray material. Dilution. Trees. ae Remarks. 
Per 
cent. 
pre 19USc) Watebon ci. 225 an. we os 100 to 160 pounds 191 85 | Used fire engine® and 
pressure. hose, large trees. 
Apr. 191918 |}. - GOS). -se ee hea: 50 pounds pressure. 2 95 | Used garden hose and 
nozzle, small trees. 
Wepie 20,1918.) 2... - DOP eat oe ae hs se GOesssscise5.: 1 80 | Used garden hose, ex- 
tension rod, and 12- 
foot platform, medi- 
um-sized tree. 
May 14,1919 |.-... Ot ete ae Dad ee eee dOSis5-5 os... 2 97 | Used garden hose, 
small tree. 
Dec. 3,1918 | Distillate emulsion....} 1 to5............- 3 60 | Hibernating larve. 
Mar. 5,1919 | Crude-oilemulsion..__|_.... GOs eee Mees 3 60 Do. 
ae a dose |sDistillateemulsions. -|1to4...) 2 S23 8 60 Do. 
TIE do-=--~-+| Kerosene emulsion. -.-|1t04.5...-...:.2.- 3 25 Do. 
pe at Gone el Distillateemulsion= =.) lto4— 22)... .: 1 65 Do. 
pret 1919 |=. : GO Gakic bea Stee ees es UC a eee 3 60 | Trees in leaf, slight 
burning. 
Jan. 19,1920 | Crude-oilemulsion....| 1 to5......-...... 4 60 | Hibernating larve. 
fhe does sees Distillate enrulsion. | 1 to 4 2.2. 3.22... 3 20 Do. 
NST SGis 5 ye SE SENG Ks se es eee cere I rok pe ce 3 20 Do. 
Apr. 12,1919 | Fish-oilsoap.......... 1 pound to 7 gal- 3 5 | Trees in leaf, no burn- 
lons. ing, young females. 
yess dope es Etinie-sulp huts a 1 GOO seo a 3 20 Do. 
Dec. 3,1918 | Miscible oil, 33°...__.. etoulo see ee 5 10 | Hibernating larve. 
Mar. 5,1919 Miscible oil, Aare ieee GOT see te 3 99 Do. 
Jan. 19,1920 |..... iis, 2. a eee fea Meee dosceperien 4 98 Do. 
eee Beene elo, ge wm | AGG... ee 2 100 Do. 
Mar. 4, 1920 ove 5 ee Se eee dsc 522 ate 4 30 Do. 
Suse ene ere O Ste en IEG 1D a 3 20 Do. 
ae: pose” MMiscibie oil, DB gat SARE OO. eae oe. = b= 3 97 Do. 
Dense ae |e aes OL os oe ek A OMe see eee 4 99 Do. 
Apr. 18, 1920) |. 222 COPE ets Paes WE Osh Re ee a= ee 2 40 | Young females. 
= oe 60 Oa ee od ees CG ae pe es ore Ocean sero: 2 95 Do. 
Sn Ee aes te “a 1A SIO gpa rae rire (BS US 0 al yee a a 1 8 Do. 
In experiment No. | the trees were large, in No. 3 the tree was 
medium-sized, and in all the others the trees were snail and could 
be sprayed from the ground with an ordinary bucket pump. This 
was the apparatus used, except in the first four experiments, where 
water was applied. All but one of the experiments were performed 
at San Jose, Calif., upon the elms growing on the normal school 
grounds. 
WASHING EXPERIMENTS. 
Washing the scale from the elm trees with a solid stream of water 
was experimented with, since fairly good results had been obtained 
in this manner by Prof. S. B. Doten, of Nevada (3, 4). In fact, his 
results seemed more satisfactory than spraying onale a lime-sulphur 
solution or kerosene emulsion. 
In preliminary experiments, it was found ‘that the best nozzle 
that could be obtained for the usual pressure of 50 pounds to the 
square inch on the garden hose was one with a 3/16-inch outlet and 
a long taper, 
