36 
BULLETIN 1474, U. S. DEPARTMENT OF AGRICULTURE 
SPRAYING EXPERIMENTS IN 1920 
Spraying experiments for the control of melanose were again 
taken up in 1920 in a mixed orange and grapefruit grove at Orlando, 
Fla., and in another grove at Winter Park, while a large commer- 
cial citrus property in Marion County, another in Polk County, and 
a third in Pinellas County were sprayed by the owners with Bor- 
deaux-oil emulsion for the control of this disease. There was an 
abundance of deadwood in all these groves, and melanose had been 
a major factor for many years. The results obtained in the com- 
mercial properties will be discussed further on. Beginning this 
year and continuing throughout the following seasons reported 
herein, the sprayed plots were enlarged to the extent that each plot 
consisted of- from 10 to 20 or more trees and required from 150 to 
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June, 1917 
200 gallons of spray for each application. This was done to approxi- 
mate commercial spraying more nearly and to overcome individual 
differences that might appear on a few trees. The pressure used 
ranged from 250 to 400 pounds, the higher pressure being used in 
the last two or three years because it became evident that more 
thorough work was done with the increased pressure. 
The groves at Orlando and Winter Park under experimental tests 
were sprayed in accordance with the data and with the results shown 
in Table 7. 
It will be seen that in the three sprayed plots in the grove at 
Orlando practically no melanose was found, and the slight trace 
which is reported may possibly have been spray injury rather than 
melanose infection. The plot receiving monthly applications was 
about as well protected as those receiving weekly sprayings, whereas 
the unsprayed part of the grove had practically 9 out of every 10 
fruits infected with melanose and for the most part the degree of 
injury could be classed as severe. 
