48 
BUHLETIX 1474, U. S. DEPARTMENT OF AGRICULTURE 
SUMMARY OF EXPERIMENTAL PLOTS SPRAYED ONCE 
Figure 12 shows in diagrammatic form the relative effectiveness 
during three seasons of single applications of Bordeaux-oil emulsion 
at 10-day intervals over a period of about two months, beginning 
about April 1. These are once-sprayed orange plots from the ex- 
periments reported in the foregoing pages. 
It will be seen that effective control was obtained in 1922 from 
April 10 to May 20, in 1923 from April 25 to June 6, and in 1924 
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Fig. 12. — Percentages of first, second, and third grade oranges, with respect to 
melanose blemish, from plots sprayed once with 3-3-50 Bordeaux mixture plus 1 
per cent oil, the application being made to the various plots on successive dates, to 
determine the best time to spray for melanose control. Results for three years 
are shown ' 
from April 7 to June 6. It further appears that on the average 
nothing was gained by spraying before April 15 and that in some 
years there was an advantage in waiting until about April 25 to 
make the application for melanose, the delay favoring the effective 
persistence of the spray coating during the whole of the five or six 
weeks' danger period following. For the three vears in question 
under the conditions prevailing in this test grove there would have 
been no serious loss in effectiveness from delaving the application 
