-30- 
steted 
The California Fruit Growers Exchange, Bureau of Fest Control, (21)/ in 
the November 1935 issue of their Pest Control Circular that Ortho Derris and 
Tox-X are less effective than oil spray against the red SDider. In the August 
1936 issue of this circular (22) it is stated that Ortho Derris and Tox-X are 
composed of a pondered insecticide containing derris added to a lo*~ dosage 
of light-medium oil, usually from 1/2 to 2/3 of 1 percent. At slightly higher 
oil dosages, up to 1.0 or 1.25 percent, they kill red spiders and es-zs, bat 
have not given control for such long periods as have the oil s-orays normally 
recommended; however, they will check spiders for at least a few months. The 
article says further: 
However, in orchards '"here red scale i b a problem and red 
spider is important, in the light of present knowledge it ^ould 
appear that these s-orays, even with the higher dosages of oil, 
should not "be substituted for the regular oil spray and fumiga- 
tion program. 
If a grower in this area (Jlivera-Dou-ney-^ittier area] must 
treat over-mature fruit for slider, and so much of his crop remains 
that he does not desire to treat over it with li^ht-medium oil, 
the other possible treatment in this area is one of the so-called 
derris sprays with 0.5 percent of light-medium oil. To date, 
derris sprays with 0.5. percent of light— medium oil have sho^n 
little oil deposit, no interference with color, will control the 
black scale satisfactorily, end handle the spider for several 
months; but, unless conditions are very favorable, additional 
slider control will have to be made within the year. ^Shile light- 
medium oil applied at this time will give a longer spider control 
than derris sprays, it is not recommended over mature fruit. 
The Exchange (23) in the September 1936 issue of its Pest Control 
Circular, stated that it is uncertain whether derris-oil sprays at 0.5 to 1.0 
percent of light-medium oil will hold the red soider (in checkj for more than 
a few months. The Exchange (24) wrote as follows in July 1937: 
Oil sprays, while the most effective of any materials against 
red spider, are not advisable, even at the low dosage of 1 t>ercent 
light-medium oil," o^ing to the danger of causing excessive drop of 
the young crop should the weather become hot. Even the so-called 
derris-oil spr'eys, made up of 0.5 percent of a light-medium oil 
and derris ponder, although a-oplied on a large acreage of oranges 
during the last few' months without apparent damage, cannot be 
recommended, for the same reason. A sudden hot spell following 
application of this materiel might hasten the drop of small fru.it. 
However, where growers feel justified in using oil, at present it 
appeers to be the safest oil type. 
In November 1937 the Exchange (25) stated that the most dependable 
material for control of red sliders on Vplencia oranges at that time of the 
year is light-medium oil, preferably 1-1/2 to 1-2/3 percent emulsion. Fhere 
