CITRUS MELANOSE AND ITS CONTROL 5 
Floyd and Stevens (11) state that melanose is caused by Phomopsis 
citri Fawcett, which speculates in deadwood, and since the fungus is 
active nearly the entire year, melanose may occur at any time when 
new growth is present. Inoculation experiments with spores from 
pure cultures of P. citri produced the disease, but no spotting resulted 
from using the mycelium or filtrate from twig washings and cultures. 
They were unable to recover the causal organism from melanose 
markings. 
Fawcett (5, 6) had previously shown that P. citri causes a stem-end 
decay of citrus fruits. 
Stevens (18) gives the results of pruning experiments in 1913 and 
1914 for melanose control in a grove that had suffered severely from 
melanose, showing that very careful pruning reduces the disease 
decidedly and that ordinary commercial pruning gives a moderately 
good control. 
Fawcett (7) calls attention to the distribution of melanose in 
Florida. He states that this disease is confined roughly between 
27y 2 ° and 29y 2 ° north latitude. North and south of these limits it 
becomes progressively less prevalent. He suggests that climatic con- 
ditions greatly influence the distribution of melanose. 
Stevens (19) obtained further positive inoculations from pure 
cultures of P. citri, but was unable to reisolate the causal organism 
from lesions or to detect it in microscopic examination. He reports 
further on four years of successful pruning experiments for melanose 
control. 
From the development of this disease on plots of grapefruit 
sprayed in 1914 and 1915 for citrus scab control, Grossenbacher (12) 
concludes that one application of Bordeaux-oil emulsion made in 
late April or early May usually gives good protection against mela- 
nose, but occasionally, when April is rainy, two applications should 
be made, the first about the middle of April and the second about 
the middle of May. 
Burger, DeBusk, and Briggs (2) failed to produce melanose in- 
fection on young oranges and grapefruit picked on May 20 and 
placed in a moist chamber in the laboratory. From these laboratory 
tests, together with general observations, they conclude that fruit 
becomes immune about June 1. From spraying tests conducted dur- 
ing 1921 and 1922 they conclude that fruit sprayed from 10 to 20 
days after the bloom has dropped will be protected from this disease. 
Winston and Bowman (24) give the results of spraying experi- 
ments conducted over several years, beginning in 1920, and particu- 
larly the results obtained in commercial grove spraying in 1922. 
They conclude that in normal years a single application of standard 
Bordeaux-oil emulsion spray completed by May 5 will give good 
commercial control of the disease, but in years especially favorable 
for the disease two applications may be necessary. Under such con- 
ditions they suggest that the first application be made between April 
1 and 10 and the second about one month later. 
Burger (1) is the first to report the occurrence of what he con- 
sidered P. citri in California, where it was found to be producing 
stem-end rot of citrus fruits. 
