40 
FLORIDA STATE HORTICULTURAL SOCIETY 
makes them unsightly and greatly lessens 
their market value. 
Melanose is similar to Citrus Scab in 
several respects, but quite different in gen¬ 
eral appearance. It attacks only the young 
growth or succulent tisse and such at¬ 
tacks never occur except when an abun¬ 
dance of moisture is present. Leaves and 
twigs are subject to attack during a com¬ 
paratively short time, from the time such 
growth appears until it begins to harden, 
which may include a period of six weeks 
or less. Fruits, however, may be affected 
from the time the bloom drops until they 
are nearing maturity. In some of our 
experiments fruits resulting from a Feb¬ 
ruary bloom were affected with Melanose 
as late as the first of August. The long 
period of susceptibility of the fruits ex¬ 
poses them to severe attacks tlirougn tne 
rainy season and doubtless a large part 
of the Melanose injury occurs at this time. 
The fungus that causes Melanose is 
found mainly in the dead parts of the 
citrus tree. Any dead wood in citrus 
trees from the smallest twigs to the larger 
branches may harbor and propagate the 
fungus from one season to the next. Dead 
fruit spurs and patches of dead bark on 
the trunks and larger branches are fre¬ 
quently filled with fruiting bodies of the 
fungus, forming infectious sources that 
are easily overlooked. The fungus does 
not grow or fruit in the tissue of the 
leaves and fruits affected by the disease, 
and Melanose does not spread from the 
spots on such material as it is sometimes 
supposed to do. Melanose injury comes 
only from the spores of the fungus that 
are formed in the dead wood in citrus 
trees, or indirectly from spores produced 
on decayed fruits beneath the trees. 
In periods of wet weather these spores 
develop rapidly and very abundantly. 
They are exuded in masses and are dis¬ 
tributed over the foliage by rains and 
heavy dews. Under such conditions on 
coming in contact with susceptible tissue, 
either fruit or leaves, melanose injury re¬ 
sults within a period of twenty-four 
hours. The spots become visible three or 
four days later. 
This production and distribution of 
spores takes place whenever there are pe¬ 
riods of rain, hence the fungus is active 
at frequent intervals throughout the year. 
This has an important bearing on the con¬ 
trol of Melanose, especially in regard to 
the protection of the fruit. The foliage 
injury is of minor importance. Owing to 
the lengthy period during which fruits are 
suspectible to attack, it is necessary to 
protect them for several months in order 
to entirely avoid injury from Melanose. 
For this reason it is difficult to outline 
a system of spraying that would be prac¬ 
ticable and at the same time effective in 
controlling the disease. 
I rather doubt if Melanose can be com¬ 
pletely controlled or held sufficiently in 
check by spraying alone, except in a few 
special cases. To spray for complete pro¬ 
tection would require a number of spray¬ 
ings throughout the season and the cost 
of such operations would probably make 
them prohibitive. There are still other 
factors that would have to be considered. 
Unless such sprayings were made in time 
and with sufficient frequency to protect 
the fruit very little good would be ac- 
