356 Journal of Agricultural Research voi. xix. No. a 



tangerine. It is interesting to compare the susceptibility of the citrangarin and the 



citrandarin. The latter was found to be as susceptible as Poncirus trifoliata and was 



very similar in character. The citrangarin, on the other hand, while it retains the 



trifoliate character, has a leaf texture more like the second parent and is much more 



resistant. 



Citranguma {Citrus nobilis var. unshiu, Satsuma, X Morton citrange). Seedlings. 



The citranguma (PL 65, G) is possibly slightly more susceptible than the Satsuma. 

 Leaf infections have been secured in both the greenhouse (CPB 48055, and 48055A) 

 and field (CPB 49773). An occasional spot has been found on the smaller twigs of 

 these plants in the greenhouse and field. 



The leaf texture and type of spot are similar to those found on the Satsuma. How- 

 ever, the leaves do not reach maturity so soon. There is a decided tendency in the 

 citranguma plants for the leaves to revert from the trifoliate to a single leaf. This 

 is especially noticeable on the new growth. 

 Citrangequat (Willits citrange X Fortunella margarita, oval kumquat). Seedlings. 



The citrangequat, without question, is the most promising hybrid so far tested. 

 No natural infections have ever been obtained in the field (CPB 48010E and 48010F). 

 Under greenhouse conditions (CPB 48010 and 48010D) only several tender leaves 

 have been infected with tiny, compact, unruptured spots (PI. 63, C). So far, the 

 citrangequat has shown more resistance than any of its parents. 



These plants (PI. 65, PI) make a splendid, rapid, straight growth. The rate of 

 growth is more rapid than that of Poncirus trifoliata, and the plants are much better 

 adapted for budding purposes. The trifoliate leaves are rather small and retain 

 considerable of the leaf texture of the kumquat. The maturation of the leaves is 

 also as rapid as in the kumquat. The leaves, especially those on the new growth, 

 have a tendency to revert to the signle leaf of the kumquat. 

 Limequat (Citrus aurantifolia, West Indian lime, X Fortunella japonica, round 



kumquat). Seedlings. 



All plants in the greenhouse (CPB 48787A, 48787B, 49787E, 49792E, and 48798E) 

 and isolation field (CPB 48792E) have been infected. Leaf, twig, thorn, branch, 

 and stem spots are common. In fact the limequat is more susceptible than either 

 parent. 



Several plants have died in the greenhouse experiments from overwatering, 

 although plants next to them have thrived. On the whole, the limequat plants 

 (PI. 66, B) worked with have not been strong nor altogether healthy. The rate of 

 growth of these plants has also been slow. It may be that strong, healthy plants 

 growing under ideal conditions would sho;v more resistance to canker. However, 

 judging from the results obtained with the plants available, the limequat is somewhat 

 susceptible. 

 Limelo {Citrus aurantifolia, West Indian lime, X C. grandis, sour pummelo). (CPB 



40502, 40526A, and 40567B, seedlings), I, II; I, III, and I, II. 



All limelos (PI. 66, A) tested have proved to be equally as susceptible as grape- 

 fruit, so that they are of no practical importance from their ability to resist canker 

 under orchard conditions. 



Bigaraldin {Citrus aurantium, sour orange, X C. miiis, calamondin). On Poncirus 

 trifoliata. 



Only one plant (CPB 50352) of this hybrid was included in the field. It was suc- 

 cessfully infected and no doubt will prove as susceptible as the sour orange. 

 Orangelo {Citrus grandis, Bowen grapefruit, X C. sinensis. Lamb summer orange). 

 Seedlings. 



