34 
trunk with a paste made of clay, lime, sulphur, and “ chips” (dry cow 
manure). At the time of our visit the application had only recently been 
made, so we were not able to see the results. It can hardly be expected 
that such a treatment will prove beneficial. The same dealer claims to 
have cured a number of trees in that way, but at the time of our visit 
to his place he was absent from home and we were thus unable to sift 
the evidence. 
IV.—SCAB. 
(1) Nature of the disease. —This disease first makes its appearance in 
the form of whitish or cream-colored spots, more commonly on the under 
side of the leaf but often on the upper side and occasionally on the 
young twigs and fruit. Those on the leaf are often accompanied by a 
depression or pit on the opposite side. These spots grow larger and 
often coalesce; ultimately they turn dark, and if abundant the leaf be¬ 
comes badly curled, twisted, or otherwise distorted and more or less 
covered with the wart-like eruptions which the disease has developed. 
(2) Distribution. —The disease is widespread; in a few localities it 
does not seem to be regarded as anything serious. In other localities, 
where it is more abundant, it is becoming the source of much alarm. 
It is not confined to young trees, but attacks equally young and old 
stock. While more abundant on the wild orange it is by no means con¬ 
fined to it, nor even to sour stock. We saw it on wild orange trees very 
commonly, on grape fruit and lemon trees frequently, and on sweet 
orange trees rarely. 
(3) Causes.— Prof. F. L. Scribner, who made a study of this disease 
in 1886,* attributed it to a parasitic fungus (a species of Cladosporium), 
whose growth in the tissues of the leaf produced the distortions and 
saps its vitality. Our own observations confirmed these conclusions. 
(4) Remedies. —In the paper above alluded to Prof. Scribner makes 
the following recommendations for spraying mixtures : (a) A solution 
of potassium bisulphide, one-half ounce to the gallon ; ( b ) liquid gri- 
son; (c) one-lialf pint carbolic acid and 1 pound of glycerine added to 
10 gallons strong soap suds. 
We could not learn that these remedies or any other treatment had 
been attempted in any of the orange regions visited. 
V.—LEAF SPOT. 
(1) Nature of disease. —On certain leaves of the orange, both wild 
and sweet, faded spots appear, varying in shape, but mostly rounded 
or oval, and in size from one-eighth of an inch to an inch in diameter. 
As the disease progresses, these spots become grayish brown and dead, 
and covered on one or both surfaces with a series of minute black 
points, which contain the fruit of the fungus, which is the cause of the 
disease. 
* Bulletin Torrey Botanical Club, xm, 181-183 (Oct., 1886), 
