20 BULLETIN 1178, XT, S. DEPARTMENT OF AGRICTJLTUBE. 
A fourth blemish was encountered in 1922, on grapefruit for the 
most part and much less frequently on oranges. This was found 
generally throughout the State regardless of the source of water 
supply or the methods of preparation of the Bordeaux mixture. 
It developed on fruits sprayed during the exceedingly dry and hot 
weather of April, almost invariably on the exposed side of fruits 
hanging on the outer branches of the tree. This injury assumed the 
pattern of spray drops and killed the outer layer of cells. The dead 
area cracked and in many instances sloughed off in the course of time, 
leaving only a faint blemish. This left a russet effect, but not the 
ordinary Bordeaux russet. 
Bordeaux russet is not encountered to any appreciable extent in 
Florida citrus groves, regardless of the stage of development or 
weather conditions when the spray is applied. When viewed from 
a practical standpoint this injury is of negligible importance. 
The total spray injury following the use of Bordeaux-oil emulsion 
is negligible ; indeed it is quite remarkable that the injury has been so 
infrequent, considering the fact that applications have been made at all 
seasons of the year under all weather conditions favorable for the 
drying of spray within a reasonable time and with various propor- 
tions of oil and several strengths of Bordeaux mixture. There are a 
number of reasons for assuming that this combination spray is much 
less likely to produce injury than either of the two materials applied 
separately. 
USEFULNESS AND LIMITATIONS OF BORDEAUX-OIL EMULSION. 
The need of a strong, lasting spray material such as Bordeaux 
mixture has long been apparent to the citrus grower who wishes to 
control scab or melanose, or both, but the use of plain Bordeaux mix- 
ture necessitates a subsequent application of oil emulsion at a rather 
early date in order to prevent excessive increases of scale insects. 
Therefore, the desirability of a combination of Bordeaux mixture 
and oil is very apparent. 
The opportune time for the spring application of oil emulsion for 
white fly and scale control coincides reasonably well with the time 
when spraying with Bordeaux mixture should be made for the 
prevention of melanose. It is evident, therefore, that if these 
materials are combined and put on in a single application the spray- 
ing costs will be greatly reduced. 
Scale crawlers are always present to a great extent in central and 
southern Florida, and an application of plain Bordeaux mixture is 
especially conducive to the rapid increase of these insects. Such 
being the case, the desirability of an oil spray combined with Bor- 
deaux mixture is quite apparent. In this connection, however, it 
should be remembered that the fungicidal properties of the Bordeaux 
mixture outlast the insecticidal effects of the oil emulsion, and 
because of the prolonged inhibitory effect of the Bordeaux mixture on 
the entomogenous fungi subsequent applications of oil emulsion are 
usually desirable to control insects. 
While it is true that scales increase somewhat following applica- 
tions of Bordeaux-oil emulsion, they are not nearly so abundant as 
after applications of plain Bordeaux mixture, and in many instances 
they increase no more rapidly than on unsprayed trees, their preva- 
lence depending upon local and seasonal conditions. 
