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the red spider; that "dth sprays of the same rotenore content with sulfonatec 
castor oil as a spreader the kill is better than with either alkylphenylben- 
zene sulfonic acid or ammonium ca seine te with rosin residue; and that pro- 
prietary thiocyenate spray is as effective as the derris spray plus sulfonate 
castor oil. None of the derris or cube sprays plus the spreader or the pro- 
prietary thiocyanate caused any permanent injury to either tomatoes or cucum- 
bers. The lauryl thiocyenate spray with a sodium oleyl sulfate, plus syn- 
thetic resin as a spreader, caused severe injury to both the foliage and the 
fruit of tomatoes. This work was referred to by the United States Department 
of Agriculture, Bureau of Entomology and Plant Quarantine ( 150 ) in 1933. 
Weigel and Johnson ( 159 ) in 1939 reported the results of tests made at 
Beltsville, Md. , on the control of red spider on cucumbers. The results of 
mortality counts of red spiders on greenhouse-grown cucumber plants after six 
sprays were applied, the first two of which were applied 4 days apart and the 
remainder at weekly intervals, indicated that in sprays containing 0.0056 
percent of rotenone and 0.01 percent of total y-r/rethrins with sulfonated 
castor oil (l:300) a greater kill resulted than when an alkylphenylbenzene- 
sulfonic acid was used as a spreader. The addition of pyrethrum to a. derris 
and sulfonated castor-oil spray did not increase its effect against red 
spiders. Sulfonated castor oil diluted 1:300 when used alone did not possess 
much toxicity to the "Voider mites. A proprietary thiocyanate gave a good 
kill of red spiders. Three applications of tartar emetic and brown sugar gs^c 
a kill of. 100 percent of the spiders, but caused serious injury to the 
cucumber plants and reduced the yield of fruit. Fnen peanut oil was used 
with derris and pyrethrum at the strength indicated above, 98.5 percent of the 
s-oiders were killed after four applications, but the treatment caused a 
yellowing of the cucumber foliage. No positive correlation was found between 
the yield of cucumbers and the control of red spiders obtained with the 
various sprays. 
In August 1939 I7eigel and Johnson ( 150 ) reported that a proprietary 
compound containing derris, an organic thiocyanate compound, pine oil, 
petroleum, and an emulsifier was less effective- than was tartar emetic with 
either bro—n sugar or glycerin when used against the red spider on chrysanth- 
emum cuttings in the laboratory. In November 1939 these authors ( 161 ) 
reported, that tests made at Beltsville, Md.lf indicate that, on the basis of 
examinations made of all living red sliders found on representative- samples 
of cucumber foliage from greenhouse-gro^n plants,, which were given a total 
of nine applications of a derris-pyrethrum-sulf onated castor-oil spray, this 
combination" proved superior to an equal number of applications of sprays 
composed of a commercially prepared thiocyanate. This confirmed the results 
obtained during the preceding three seasons. Under the conditions of this 
.experiment no differences ^ere revealed in the numerical production of 
cucumbers from plants treated ^ith these t™o sprays, but the per-plant pro- 
duction was considerably reduced in the check plots. It should be emphasized, 
however, that the plants in the Check plots produced a higher percentage of 
Grade No. 1 cucumbers than the plants subjected to either of the spray treat- 
ments, indicating the possibility Of mechanical injury to the flowers or young 
cucumbers by the spray. The derris-pyrethrun-sulfonated castor-oil spray did 
