342 
Journal of Agricultural Research 
Vol. XIV, No. 9 
EDIBLE FRUITS WITH STALKED PULP VESICLES 
Poncirus trifoliata (L.) Raf. ( Citrus trifoliata L.). Trifoliate orange (seedling, Ala¬ 
bama), II. 
The trifoliate orange, which is a small spiny deciduous tree native to North China, 
is used to the exclusion of all other plants as a stock for Citrus spp. in Alabama. 
Hedges and trees are also widely scattered through the State. It has been fairly 
well established that Citrus-canker was imported from Japan into Alabama, directly 
and indirectly, on trifoliate seedlings. In Alabama it ranks next to grapefruit in 
susceptibility to canker in the field. With the gradual elimination of grapefruit 
growing from Alabama, the trifoliate orange becomes of major importance in the 
eradication of canker in that State. 
Unfortunately the plant included in the experiment remained dormant, and no 
new growth developed. However, a few infections have occurred on the old leaves. 
Owing to the lack of good infections for comparison, the type of spots produced will 
be omitted. 
Eremocitrus glauca (Lindl.) Swingle. ( Triphasia glauca Lindl.; Atalantia glauca 
Benth.) Australian desert kumquat (CPB 7239, seedling), I, II. 
A small hardy drougth-resistant tree with very small leaves and slender spiny twigs, 
found in Australia. It is one of the most interesting plants in Mr. Swingle’s col¬ 
lection. 
A 
Typical Citrus-canker spots appeared on the leaves, twigs, and thorns six weeks 
after inoculation in Experiment I and in three months in Experiment II. Infection 
apparently takes place only on the upper surface of the leaves. The spots are minute, 
0.3-0.5 mm. in diameter, circular, light brown at first, becoming darker with age, 
raised, compact, with little or no cork. The spots do not push through the leaf. 
Only an indistinct oily outline is present with a rather wide yellow zone. The 
spots increase very slowly with age, but one spot is sufficient to cause defoliation. 
The spots on the thorns and twigs are identical with those on the leaves. 
It is extremely difficult to judge its relative susceptibility, owing to the peculiar 
nature of the plant. However, Citrus-canker attacks the leaves, thorns, and twigs, 
and as one spot is sufficient to cause defoliation, it is apparently quite susceptible. 
Fortunella margarita (Lour.) Swingle. ( Citrus margarita Lour.). Oval kumquat (CPB 
7*597, seedling), II. 
The oval kumquat is quite widely grown in the Gulf coast section of Alabama. 
In the field kumquats have been reported as susceptible in only one or two cases, 
so that they are considered to be resistant by most growers. 
As the plant (33 inches) was cut back for shipment, the young shoots were in excel¬ 
lent shape for infection at the time of inoculation. Citrus-canker spots appeared 
two months after inoculation and increased quite rapidly in numbers, so that prac¬ 
tically all the mature leaves had one or more spots. 
These results are quite interesting, in view of the resistance of kumquats shown in 
the field. The fact that maximum infection was obtained under the conditions 
governing the inoculations is very well shown here. 
The spots are not numerous, averaging slightly above 1 mm. in diameter, chocolate- 
brown in color, slightly raised, compact, and occasionally corky. Spots rarely pene¬ 
trate the upper surface, sometimes showing as a small, flat, oily, light-brown blister. 
The oily outline is very distinct, and no yellow zone is present. Citrus-canker does 
not cause defoliation, nor any apparent injury to the leaves. Only leaf infections 
have developed. Judging from the size and character of the spots, the plant is fairly 
resistant to canker, and it is not severe enough to cause any injury to the trees. 
Fortunella crassifolia Swingle. Meiwa kumquat (CPB 11047, seedlings), I, II. 
A little-known kumquat recently introduced into the United States by Japanese 
nurserymen. 
