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_ light lemon yellow, becoming colored prematurely (PI. III, figs. 1 and 2). 
The fruits are very commonly more or less disfigured by the characteristic 
| reddish-brown stain. A very large percentage split open and drop 
before ripening (fig.4). The loss from this malady is about $100,000 
annually in Florida. Withholding all organic nitrogenous manures, 
- ceasing to cultivate, and mulching the soil have been found beneficial 
treatments. In cases where the disease has been produced by wet soils 
| good drainage will frequently be found an effective remedy. 
3. Scab or verrucosis attacks principally sour oranges and lemons, 
the common sweet orange being exempt. It occurs in the United 
| States, Australia, and Japan, from which latter country it was prob- 
| ably introduced into America. It causes small excrescences to appear 
on the young leaves and fruits (Pls. V, VI). These excrescences are 
| at first of a pale, watery green color, but soon become coated with a 
| dusky fungous growth composed of a species of Cladosporium (the par- 
asite which causes the disease). The tissues of the warts infested by 
the fungus are cut off from those below by a formation of cork, which 
ultimately becomes so abundant as to give the excrescence a gray color. 
The full-grown warts are ;/; to 4 of an inch in diameter and are often 
confluent. When attacked while still very young, the leaves and fruits 
are greatly distorted by the disease. In the fruit, especially, the warts 
cause the tissues below to grow too fast and to form large bumps. 
‘| These, with the gray excrescences, so disfigure the fruit as to render it 
nearly valueless. The fungous parasite causing scab is able to spread 
| and infect new spots only during moist weather. For this reason very 
| dry regions are nearly exempt from the malady. The loss from this 
| disease results principally from its action in disfiguring lemons. It 
| does most harm in Florida, where it causes an annual loss of not far 
| from $50,000. The disease can be prevented on lemons by spraying 
the young fruits from three to five times with ammoniacal solution of 
copper carbonate. 
4, Sooty mold is a black fungus, which follows the attacks of certain 
| honeydew-secreting insects. It may be recognized by the sooty black 
} membrane which it forms principally over the upper surfaces of the 
| leaves, fruits, and stems (Pl. VII, fig. 1). The disease greatly reduces 
the productivity of the trees, and the oranges formed are so badly dis- 
i figured by the covering of sooty mold as to be rendered unsalable. The 
J annual loss in Florida is not far from $50,000. Thorough spraying 
_} with resin wash has been found very effective. Between December and 
_@ March of each year three sprayings should be made. Fumigation with 
| hydrocyanic acid gas has also been found an effective remedy. The 
| applications should be made during the winter. A parasitic fungus 
| (Aschersonia tahitensis, Pl. VII, fig. 2) has been found which promises 
_ } to be a very great aid in combating this malady. 
5. Foot rot or mal-di-gomma is the most widespread of all orange dis- 
cases. The total damage which it causes is greater than that resulting 
