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tions may be separated as distinct physiologic races in the future 
by using additional oat varictics. 
Experiments on the Control of Iris Thrips 
Spray tests for the control of iris thrips, made by Dr. L. 
Gordon Utter, in cooperation with Dr. Floyd F. Smith, of the 
Division of Truck Crop and Garden Insect Investigations, Bureau 
of Entomology and Plant Quarantine, Washington, D. C., were 
brought to a conclusion. Eight applications of various spray 
jinations and dusts were made on test plots of iris plants at 
Spray combinations of 
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com 
weekly intervals during May and June. 
derris powder (.02 per cent. rotenone) with sulfonated castor oil 
(1-400) as a spreader, and 40 per cent. nicotine sulfate (1-450) 
with Grasselli Spreader Sticker (1-1000) continued to give ex- 
ceedingly high control of the thrips. A commercial derris ex- 
tract spray (1 per cent. rotenone) and a derris dust (1 per cent. 
rotenone) also appeared to be effective. The results obtained 
with spray combinations having reduced derris or nicotine con- 
tent were not sufficient to recommend them for general use. ‘This 
is also true for certain commercial insecticides included in these 
— 
tests for the first time. 
Preliminary tests undertaken by Dr. Smith at Beltsville, Md., 
indicated that the iris thrips could be killed within the iris plants 
when fumigated with methyl bromide at the rate of 24% Ibs. per 
1000 cu. ft. of space for 244 hours at 74-78° F. Consequently, 
tests were made at the Bureau of Entomology and Plant Quaran- 
tine Bulb Station, Babylon, N. Y., in cooperation with Mr. S. F. 
Blanton, to determine the tolerance of iris to fumigations with 
methyl bromide. Planting divisions of numerous varicties of 
Japanese and bearded iris and several iris species, including hy- 
brids, were subjected to methyl bromide fumigations at the 244 
and 3 lbs. rate in April, May, July, and September. Both treated 
and untreated divisions were planted in field plots. The treat- 
ment periods generally coincided with the time of year when some 
of the species or varieties are best transplanted. Preliminary 
results have indicated that no critical differences existed between 
the treated plants or between them and the untreated ones in 
any of the iris varieties or species tested. In general, the April 
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