8 Hi lleti.n 1178, v. s. DEPARTMENT OF AGRICULTURE. 
Oil No. 1 has a rather low specific gravity, is rather volatile, is not 
particularly viscous, and has not proved very effective as a general 
oil spray for use in Florida citrus groves. It is quite satisfactory for 
the control of white flies but only partially effective against scale 
insects. Oil No. 2, which is considerably heavier and murh more 
viscous and less volatile, has proved quite satisfactory in most cases 
and is generally used throughout the State. Oil No. 3 is perhaps 
too heavy for general use in the spring and early summer, when the 
fruit and leaves are quite tender. It is eminently satisfactory for 
spraying during the rainy season and gives very much better results 
in a severe scale infestation than either No. 1 or No. 2. Nevertheless, 
it should be used with caution and except in rare instances only 
during the rainy season, the fall and winter. 
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/92B 
Fig. 3.— Diagram showing the persistence of copper residue on citrus leaves compared with the 
rainfall at Orlando, Fla., in 1922. 
BORDEAUX MDITURES. 
For many years the standard method of preparation has been to 
pour the dilute limewater and dilute bluestone solutions together 
simultaneously. For comparative purposes this method was used 
in the early stages of this work in some of the field experiments 
herein recorded. Hawkins {2) has shown that Bordeaux mixture 
made by pouring concentrated bluestone solution into dilute lime- 
water, or vice versa, results in a mixture which, after thorough 
agitation, such as is common in power sprayers, settles almost as 
slowly as the Bordeaux mixture resulting from pouring the two 
dilute ingredients together simultaneously. To meet local con- 
ditions, Hawkins's method is the one usually employed in field 
practice. 
In most of the experiments the concentrated limewater was poured 
into the dilute bluestone solution, but sometimes the reverse order was 
followed. In some cases the two concentrates were poured to- 
gether simultaneously, resulting in a Bordeaux mixture that settles ^ 
