36 
The infection, it appears, usually takes place at an early stage in the 
development of the leaves and stems, and if the disease becomes severe 
the affected organs are considerably modified in appearance. The 
leaves become greatly distorted and wrinkled and remain much smaller 
and more pointed than normally. Many of the leaves fall before reach- 
ing maturity, only a scanty foliage remaining on badly affected branches. 
The branches are also considerably contorted and stunted in severe 
attacks (fig. 6). 
Cause.—From studies that have been made of this disease it seems 
very probable that it is caused by some vegetable parasite, although the 
microscopic studies which have thus far been carried on have failed to 
reveal the presence of any such organism. The disease is apparently 
contagious, spreading from definite centers. In some groves infected 
areas are plainly seen. In the centers of these areas, where the disease 
first started, the trees will be found to be very badly affected, but 
‘toward the margins the malady gradually becomes less apparent. 
Melanose appears to be of an entirely local nature. In its growth 
and development each spot is entirely independent of any other spot, 
probably being caused by a separate infection. The tissue between 
the diseased spots is evidently perfectly healthy outside of the gen- 
eral debility which results from the infection of such a large portion 
of the leaf. The strict localization of the disease, so similar to what 
occurs in scab, again strongly suggests that the disease is caused by 
some vegetable parasite. Infection can take place apparently only 
when the tissues are quite young. If the leaves and stems escape the 
disease until they are nearly full grown the danger of infection is past. 
This is the case also with fruits, and therefore spraying to prevent the 
disease must be done early, while the fruits are small. After they 
reach an inch in diameter they appear to be safe from infection and 
spraying may then be discontinued. 
Preventive measures.—In the summer of 1894 experiments with vari- 
ous fungicides were carried on at Stanton and Citra, with a view to 
find a preventive of the disease. The copper fungicides, i. e., Bor- 
deaux mixture and ammoniacal solution of copper carbonate, were 
found to almost wholly prevent the disease if properly applied. In 
two plats of lemon trees at Stanton, sprayed with Bordeaux mixtures 
(6 pounds of copper sulphate and 34 pounds of lime to 50 gallons of 
water), melanose was absolutely prevented, the most careful search 
failing to disclose a single fruit showing the characteristic spots. The 
sprayings were made once a week and twice a week, respectively, for a 
term of ten weeks, beginning February 3. On an orange tree sprayed 
at the same time with the lemons the treatment was equally effective. 
However, both the lemon trees and orange trees were somewhat injured 
by the Bordeaux mixture, probably largely because of the numerous 
sprayings given. On adjoining unsprayed lemon trees from 2 to 4 per 
cent of the fruits and a larger per cent of the foliage were considerably 
