BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 27 
New Compounds Highly Toxic to Resistant Spicier Mites on Roses 
Investigations were continued in Maryland on the development of 
more effective insecticides and methods for their application to control 
various species of insects and mites infesting roses and other major 
floral and vegetable crops grown in greenhouses and in the field. 
Large-scale tests in greenhouses showed that combustible powders con- 
taining DMC (Dimite) are highly toxic to resistant spider mites and 
that three applications at 5-day intervals resulted in practical elimina- 
tion of these pests on roses. Aramite in sprays or aerosols was shown 
to be highly effective against resistant spider mites on roses. Aramite 
sprays in a combination of treatments with schradan or E-1059 aero- 
sols have been tested in commercial greenhouses on roses and have 
given satisfactory control of resistant spider mites during the summer 
and fall seasons. In laboratory tests with 26 acaracides the materials 
were highly toxic to non-resistant spider mites but only Aramite, 
/?-chlorophenyl y>chlorobenzene sulfonate (Ovotran), DMC, R-24-2 
(Sulphenone) and compound 923 (Genitol) were toxic to resistant 
strains of these mites. 
Systemic Insecticide Breaks Down Rapidly in Plant 
Laboratory experiments involving the introduction of measured 
quantities of schradan into chrysanthemum cuttings, through nutrient 
solutions, or by foliage applications, followed by subsequent chemical 
analyses, showed that this systemic insecticide' breaks down rapidly 
in the plant. Tests indicated a difference in the ability of various 
plants to retain schradan after absorption. Considerable quantities 
of this material were found in seeds of peas and beans when low 
dosages were applied to the foliage of the plant but very little schradan 
was found in the fruits of tomatoes even after excessive applications 
to the foliage. 
Tolerance of Mushrooms to Different Insecticides Tested 
Experiments at Beltsville. Md., continued to demonstrate that pyre- 
thrum drenches applied to mushroom beds between flushes or just as 
the young mushrooms begin to appear above the soil surface do not 
injure the crop or reduce the yield. Allethrin and methoxychlor 
also did not cause injury nor did three well-known wetting agents — 
Santomerse, Triton X-100, and Dreft. In exploratory tests early in 
1951 the miticides Aramite. DMC, p-chlorophenyl p-chlorobenzene 
sulfonate, and IN-4200 did not cause injury. In tolerance tests with 
dusts, allethrin, pyrethrum. and lindane did not cause injury. The 
lindane dusts apparently did not cause any off-flavors in the cooked 
mushrooms. Lindane emulsion spray, however, caused off-flavors 
Practical Control for Pickleworm on Cucumbers and 
Squash Sought 
Work on the control of the pickleworm on cucumbers and squash 
in South Carolina showed that this insect can be controlled bv weekly 
applications of a 1-percent lindane dust, beginning when the plants 
