SPRAYING FLORIDA CITRUS FRUITS a 
The pruning out of deadwood within the practical limits of eco- 
nomical grove operation has been found to have very little if any 
immediate effect in controlling Phomopsis stem-end rot.’ It reduces 
Diplodia stem-end rot about 50 per cent. With Diplodia causing 
perhaps one-fourth of all the expected stem-end rot, this reduction 
would amount to one-eighth of the total stem-end rot, which is not 
enough to justify any special expenditures for pruning above what 
is ordinarily required in good grove practice. Probably the greater 
effectiveness of pruning against Diplodia rot is due to the fact that 
Diplodia is found for the most part on the larger twigs and limbs 
that can be rather thoroughly removed. It is not practicable to 
remove the innumerable small sprigs and fruit stems that regularly 
harbor Phomopsis, and so infection by this fungus is not materially 
checked by the ordinary pruning. 
Spraying experiments conducted in Florida by the Office of 
Fruit Diseases during 1920 and the seasons following have shown 
that melanose, caused by the same fungus (Phomopsis) that pro- 
duces the more usual type of stem-end rot, can be satisfactorily con- 
trolled by one application, made the latter part of April or early 
in May, of 3-83-50 Bordeaux mixture plus 1 per cent of oil as emul- 
sion.2 Figure 1, reproduced from the bulletin reporting that work, 
shows in diagrammatic form the relative effectiveness against mel- 
anose, during three of the seasons in question, of single applications 
of Bordeaux-oil emulsion at 10-day intervals over a period of about 
two months beginning about April 1. 
EXPERIMENTAL METHODS 
The present investigation, begun in 1920, has had for its object 
to determine what effect, if any, spraying the fruit with fungicides 
has on its keeping qualities. At the outset it was assumed that sprays 
applied in the fall or during the summer rainy season might be most 
effective for this purpose. With the development of extensive tests 
in April and May for melanose control, to which reference has been 
made, these experimental plots were drawn upon for samples for 
holding tests, thus covering the whole period of development of the 
fruit. 
The experiments were conducted at Orlando, Fla. Large seedling 
orange trees with a considerable amount of dead twigs to harbor the 
stem-end rot fungi were used. Grapefruits were tested sufficiently on 
all important points to warrant extending to them the conclusions 
drawn from the tests on oranges. The spray was applied with paired 
angle disk nozzles and with a pressure of approximately 300 pounds 
or more. Ten to twenty-five trees, requiring about 8 gallons of 
spray to the tree, were included in each plot, and the plots were 
duplicated. The experimental grove regularly received a general oil 
spraying each year about July 1 and usually an additional application 
in the fall. These treatments successfully kept scale insects under 
control, even where several applications of Bordeaux mixture were 
made yearly. (Ordinarily citrus insect pests increase following the 
2 WINSTON, J. R., Futron, H. R., and Bowman, J. J. COMMERCIAL CONTROL OF CITRUS 
STEM-END ROT. U.S. Dept. Agr. Cire. 293, 10 p., illus. 1923. 
3 WINSTON, J. R., BOWMAN, J. J., and BacH, W. J. CITRUS MELANOSE AND ITS CONTROL, 
U. S. Dept. Agr. Bul. 1474, 63 p., illus, 1927. 
