42 ANNUAL in: PORTS OF DEPARTMENT OF AGRICULTURE, 195 3 
resistant to greenbugs when the aphids are allowed to build up grad- 
ually. Both variet ies are very suscept ible to a sudden heavy greenbug 
infestation. Several other varieties appear to be unfavor 
greenbug reproduction. For example, erreenbugs reproduced three 
times as cast on Pawnee as on Mahmoudi ( J. I. 2099. 
Field tests were made of 20 varieties of oats, 24 varieties of barley, 
and 28 varieties of wheal that had shown some greenbug resistance 
under greenhouse conditions. All barley varieties showed a high 
degree of resistance. Kearney C. I. 7580 and unnamed ('. I. l_ 
appeared to be more resistant than Omugi barley. Andrew. Bond x 
Rainbow Sel., and a Clinton X Ventura selection were among the i 
resistant oat varieties tested. 
Cultural and Insecticidal Controls Effective Against Brown 
Wheat Mite 
Tillage experiments to determine the effect of different cultural 
practices on the brown wheat mite (Petrobia latem) gave a 95-percent 
reduction in the numbers of newly hatched mite^ when the eggs were 
buried to a depth of one inch, and 1)7 percent when buried at 2} -- and 
5-inch depths. Eggs used in the experiments were extracted I 
samples of wheat stubble and soil by moan? of a specially de- 
apparatus. The susceptibility to cultural controls of newly hatched 
mites may prove useful in further control experiments. 
Various chemical formulations were also tested in southwestern 
Kansas against this mite. Airplane application of \ '2 pound of para- 
thion per acre was required for control of the mite. None of the new 
specific miticides showed outstanding performance against the mite 
when applied at recommended dosages or even at doubled dos 
Against adult mites Systox at 14 pound per acre was about as effective 
as parathion at y 2 pound. Parathion at ^4 pound was more effective 
than Metacide at "> L . pound per acre. One-half pound of schradan per 
acre was next in effectiveness. Emulsions were much less effective 
than solutions in aerial sprays. Used in ground equipment, emuls 
were slightly more effective than suspensions, and the flat type nozzle 
as efficient as the cone type. The latter observation is of considerable 
importance, since many farmers are equipped with flat type nozzles 
for use in weed control. 
This work on the brown wheat mite was conducted in cooperation 
with the Kansas Agricultural Experiment Station. 
Four Insect Vectors May Be Involved in Transmission of W heal 
Yellow Streak Mosaic 
Possible Instances of transmission of wheat yellow streak mosaic 
by Insects were obtained with 3 of -J 7 species studied in greenhouse tests 
in L952. The species involved were the wheat stem maggot M 
amerioana: flea beetles of the family Phatacridcu • and the leafhopper 
Endria inimu <>. A.boui 3,000 insects were used in t he 250 experiments 
performed during the year. 
Early in L953, following information received from J. T. Slykl 
Science Service, Canada Department of Agriculture, Lethbridge, 
Alherta, Canada, that he had transmitted the mosaic with the erio 
