40 ANNUAL REPORTS OF DEPARTMENT OF AGBK DXTURE, 1951 
from the original colonization tree during a few months for recoloniza- 
t ion in <>i her part - of Mexico. 
Experiments Confirm N alue of Parathion in Control of Scale [naecti 
on Citnifl 
Parathion has marked advantages over oil sprays for the control 
of scale insects on citrus, according to the results of experiments re- 
cently completed in Florida. Parathion may be added to regularly 
scheduled sulfur sprays used against the citrus rust mite, whereas 
the oil spray may not be combined with sulfur, so that extra spray- 
ings are necessary. In the experiments two sprayings with wettable 
sulfur plus parathion ( 1 or 2 pounds of L5-percent wettable powder), 
in midsummer and fall, nave as good control of purple scale and 
Florida red scale as did two of the oil, and at the same time controlled 
the rust mite. A combination spray of wettable sulfur, wettable 
parathion, and bis (p-chlorophenoxy) methane (Neotran), when used 
in July and in the fall gave good control of tin 1 nisi mite, purple 
scale, and the citrus red mite without harm to Valencia orange I 
Parathion had no unfavorable effect on the quality of the fruit. A 
tuallv. it advanced the maturity of oranges slightly. In contrast, oil 
sprays applied late in the summer or in the fall Lowered the quality 
of t he fruit and delayed its maturity. 
Iii California one annual application to citrus of a -pray of para- 
thion with L.75 percent of a special light oil (lighter than any of the 
light oils registered in California) continued to <_ r ive better control 
than two applications of a heavier oil alone. Fall spraying gave 
more clean lemon fruits than spring spraying. Other experiment- 
indicate that in commercial sprays containing 1 pound of 25-percent 
parathion wettable powder to Inn gallons, oil concentration may he 
reduced without reducing effectiveness. One gallon of oil phi- 0.5 
pound of parathion to loo gallons <»f water was superior to the full 
dosage of oil alone. This reduced amount of oil lessened some of the 
object ionable effect of oil sprays. 
Add it ion of 2,4-D to sprays containing parathion and oil continued 
to prevent leaf drop on lemons in California. In some area- there 
Was no leaf drop whether or not 2,4-D was added. Spray- of 1.5 
gallons <>r more of oil pin- 0.5 pound of 25-percent parathion to loo 
gallons have sometimes caused injury to oranges. No injury followed 
the application of 1 percent of oil with pa rat hi on. 
A -pray containing the special light oil pin- parathion injured 
oranges less than regular oil -pray- in most test -. hut more in one test. 
There wa- no injuiw of commercial importance from parathion alone. 
Special light oil pin- parathion and parathion alone cau-ed no reduc- 
tion in quality or delay in maturity of oranges. 
Experimental results and commercial experience in California con- 
firmed earlier conclusions that thorough application and an adequate 
dosage of parathion arc necessary for satisfactory control of Cali- 
fornia red scale. When an infestation is distributed <>\er all part- of 
the tree, at least 2 pounds of a 25 percent wettable powder to 100 gal - 
-needed. with ver^ light infe-tatioti- on green twigs and f ruit, 
more dilute spra} - gn e good results. 
