June i6,1923 
Susceptibility of Citrus Fruits 
959 
All evidences from our observations show that scab is limited to the 
Citrus fruits and their hybrids, with the exception of Poncirus trifoliata. 
The species and varieties within a group vary in their susceptibility to 
scab. A good example of this occurs in the Citrus grandis or grapefruit 
group, and is further accentuated among the hybrids. Susceptibility to 
scab varies not only from season to season, depending on weather condi¬ 
tions, but varies even within the same season. Thus a bad scab year 
is determined largely by weather conditions just at the time of the forma¬ 
tion of the leaves and fruit. In most cases, scab susceptibility narrows 
down to the reaction of the host plant to environmental conditions, 
essential to scab infection and the development of the disease. This 
does not necessarily mean conditions favorable to the best and most 
normal development of the plants, as under these conditions few of the 
plants are susceptible to scab. It is extremely interesting to note that 
in this connection a number of plants which are promising as canker 
resistant are as a whole susceptible to scab. 
LITERATURE CITED 
(1) Earte, F. S, 
1920. THE CULTIVATION OF CITRUS FRUITS IN PORTO RICO. Pofto RicO InS. 
Exp. Sta. Circ. 28, 20 p. 
(2) Fawcett, H. S. 
1921. SOME RELATIONS OF TEMPERATURE TO GROWTH AND INFECTION IN THE 
CITRUS SCAB FUNGUS CLADOSPORIUM ciTRi. In Jotif. Agf. Research, 
V. 21, p. 243-253. Literature cited, p. 253. 
(3) Peltier, George L. 
1918. susceptibility and RESISTANCE TO CITRUS-CANKER OF THE WILD RELA¬ 
TIVES, CITRUS FRUITS, AND HYBRIDS OF THE GENUS CITRUS. In Jour. 
Agr. Research, v. 14, p. 337-358, pi. 50-53. Literature cited, p. 356- 
357 - 
(4) -and Frederick, W. J. 
1920. RELATIVE susceptibility TO CITRUS-CANKER OF DIFFERENT SPECIES AND 
HYBRIDS OF THE GENUS CITRUS, INCLUDING THE WILD RELATIVES. In 
Jour. Agr. Research, v. 19, p. 339-362, pi. 57-68. Literature cited, 
p. 361-362. 
(s)- 
1922. RELATIVE susceptibility OF CITRUS PLANTS TO CLADOSPORIUM CITRI 
MASSEE. (Abstract.) In Phytopathology, v. 12, p. 57. 
(6) Reinking, Otto A. 
1919. diseases of ECONOMIC PLANTS IN SOUTHERN CHINA. In Philippine 
Agricultmist, v. 8, p. 109-135, 3 pi. 
(7) Stevens, H. E. 
1916. CITRUS SCAB. In Fla, Agr. Exp. Sta. Ann. Rpt. [i9i4]/i5, p. xciii. 
1918. FLORIDA CITRUS DISEASES. Fla. Agr. Exp. Sta. Bui. 150, p. 13-110# 
54 fig. 
