16 
BULLETIN 1178, U. S. DEPARTMENT OF AGRICULTURE. 
Scale insects following the use of Bordeaux-oil emulsion did not 
become very abundant this year with one or two exceptions. Prac- 
tically all the plats received a final application of straight oil emulsion 
in November. 
Counts were made several times during the summer to determine 
the abundance of rust mites on the several plats. These data are 
presented in Table 7. The mites on the sulphur plats represent those 
found on the combined 20 plats. The mites found on the copper 
plats represent those counted on the entire 18 plats. 
There were about ten times as many mites following the use of 
copper sprays as there were following the use of sulphur sprays. On 
August 11 the check plat had practically no ]nites, while they were 
present in great numbers on the plats receiving copper sprays. This 
difference is probably accounted for by the effect of the copper-spray 
residue on the fungi supposed to be parasitic upon the rust mite. 
Mealybugs. 8 — There was an opportunity in 1921 to collect some 
data on the abundance of mealybugs following the copper and sul- 
phur sprays used on the various plats in grove D. It has been shown 
by Speare (9) that mealybugs in Florida are attacked by the fungus 
EntomopJithora fumosa Speare, which appears to be an important 
factor in limiting the numbers of this insect. The use of fungicides, 
therefore, would probably prevent the normal development of this 
entomogenous fungus, and mealybugs would become more abundant. 
The data given in Table 8 were obtained on August 11, when mealy- 
bug infestation had reached its maximum for the season. 
Table 8. — Occurrence of mealybugs on plats sprayed with sulphur compounds 
pared with those plats sprayed with copper compounds and the unsprayed cht 
in 1921 
as com- 
unsprayed check plats 
Treatment. 
Total 
number 
of trees. 
Mealybugs absent. 
Trees. Per cent. 
Mealybugs scarce. 
Trees. Per cent. 
Mealybugs 
abundant. 
Trees. Per cent. 
Unsprayed 
Sulphur sprays 
Copper sprays. 
255 
23 
53 
184 
13 
34 
72 
56.5 
64.1 
22 
30 
20.7 
While the foregoing results are not striking, they indicate that 
fungicides applied for melanose control during the season increased 
the infestation of mealybugs. Similar results were obtained the 
following year. Plats receiving copper sprays had a much greater 
infestation of mealybugs than either the sulphur-sprayed plats or 
the unsprayed trees. 
1922 TREATMENTS. 
In 1922 the same grove (grove D, at Orlando, Fla.) was sprayed 
experimentally, beginning April 10 and ending October 10. Various 
strengths of Bordeaux mixture plus 1 per cent of oil as emulsion as 
well as Bordeaux mixtures prepared by different methods were 
tested. The plats received from one to as many as seven applications. 
Again, excellent results were obtained against melanose. On some 
trees slight spray-burn was noted, which will be discussed later. 
8 Pseudococcus citri Risso. 
