-31- 
growers prefer less oil, even with the possibility of shorter control, the 
better known oil-rotenone combi nations, sv.ch as Botcmo-iR or Tox-X, may bo usod. 
For growers who refuse to accept the risk attendant on the use of miscible oil 
and lime-sulfur on navel oranges, an alternative is low-dosage oil-rotenone. 
With this material, however, there is the possibility of retarded fru.it 
coloration, which may necessitate late shipment. In December 1937 the Exchange 
(26) recommended rotenenc-oil sprays for the control of the red spider on lemons 
and oranges. These sprays are usable in all districts, whereas the use of 
miscible oil and lime-sulfur is limited to interior areas, 
Rotcnone-oil products were recommended by the California. Fruit Growers 
Exchange (|27) in January 1938, for the control of red spider on lemons in the 
coastal areas' and on' oranges in the interior. In February 1938, the Exchange 
(28) recommended oil-rotenone combinations for combating the red spider, the 
citrus aphid, and the immature black scale. A suitable spray is made from' 0,5 
to 0,75 gallons of light-medium oil, 1 tc 4 pounds (depending on the brand) 
of rotenone powder, and water to make 100 gallons. In March 1938, the Exchange 
(2S) reported that the beginning : stages of water rot- became evident the last 
week in December in seme oil-sprayed Thompson Navel Orchards in eastern Los 
Angeles County, but the rot was arrested by drying weather. There appeared to 
be no outstanding difference between orchards sprayed with emulsion and those 
sprayed with emulsiblc oil's, Oil-rotenone combinations containing less oil 
showed less damage than the regular oil sprays; in- fact, the extent of watcr-rot 
development was largely in proportion to the percentage cf cil used. Sprays 
carrying less than 1 percent of cil showed much less ret than sprays carrying 
1.5 percent cr more. For the control of red spiders en oranges in the coastal 
c.r r a of California it was stated that, since aphid s are almost always present 
at this time of year along with the r cd spider, one of the rctenone-oil sprays 
with 0,5 percent of light-medium oil she- Id bo the preferred treatment and will 
control both pests. The most widely used rotencne-oil sprays of known value 
arc Botanc-R, Tox-X, and Rctox, 
In Kay 1038 the California Fruit Growers' Exchange (30) discussed the red 
spider situation* Fcr lemons, in groves where there is a considerable amount 
of maturing fruit cr where spring fumigation has been practiced, light-medium 
oil (1,5 to 1.67 percent) , or one of the rotoncne-oil sprays at 0,5 tc 0.67 
percent of light-medium oil, night be given preference. In July 1938, • tho 
Exchange (31) advised growers of oranges in Ventura ' County as follows: "If 
spray is used en oranges fcr black scale, low-dosage derris-oil will handlo the 
black scale, and in most cases the red spider, and is easier on the trees and 
fruit." 
The Exchange (32) in January 1939 recommended rotencme-oil for use against 
red spiders on lemons in coastal areas. In April 1939 it (33) recommended one 
of the rotenono-oil sprays with l/2 of 1 percent of lights-medium oil as tho 
preferred treatment to handle both aphids and the red spider on oranges in the 
coastal areas. In July 1939 the Exchange (54) recommended rotcnone-oil sprays 
using l/2 to 2/3 of 1 pcrtcent of light-medium oil for the control of the black 
scale and the red spider in Ventura County, where treatment must be made over 
rips fruit. In August 1B39 it (35) discussed the control of the red spider in 
coastal citrus orchards. In areas where a sprr.y is rise necessary f^r black 
