344 Journal of Agricultural Research voi. xix. no. s 



that canker may lie dormant in the bark tissues of the old wood and overwinter for a 



period of six months (7). 



Eremocitrus glauca (Lindl.) Swingle (Triphasia glauca Lindl.; Atalantia glatica 



Benth.). Australian desert kumquat (CPB 7239 and 7397, seedlings), I, II, and 



III, in field, 1917. 



All plants have shown infection, varying with their condition. Canker (PI. 59, D) 

 has been observed on the leaves, tlioms, twigs, and old wood. A considerable degree 

 of susceptibility is sho\^'n; and, under favorable conditions, the species should be 

 successfully inoculated in the field, although such attempts have proved negative 

 so far. 

 Fortunella margarita (Lour.) Swingle {Citrus margarita Lour.). Oval kumquat 



(CPB 7597, seedlings), I, II, III, in field, 1918. 

 Fortunella crassifolia Swingle. Meiwa kumquat (CPB 11047, seedlings), I, II (2 



plants), III, in field, 1917 and 1918. 

 Fortunella japonica (Thunb.) Swingle {Citrus japonica Thunb.). Round kumquat 



(CPB 11301, seedlings), I, III, in field, 1918. 

 Fortunella Hindsii (Oliver) Swingle (5c/eroy/jiw Hindsii Champ., Atalantia Hindsii 



Oliver). Hongkong wild kumquat (CPB 11046C and 11046A, seedlings), I, II, 



III, and I,' in field, 1917 and 1918. 



All four species of kumquats have been successfully inoculated, although in all 

 cases with some difficulty. From the results so far obtained no one of the first three 

 species appears to be more susceptible than the other, the amount of infection 

 depending on the growing condition of the individual. Judging from the type and 

 number of spots (PI. 60, C) Fortunella Hindsii is the most susceptible in that the 

 spots are ruptured and corky. 



As a rule, the spots on the other three species are characterized by being small, 

 slow-growing, scattering, very dark, compact, and unruptured (PI. 60, A). A few 

 slightly ruptured, corky spots have been found on the plants, but usually at wounds. 



Three plants of Fortunella Hindsii have been successfully inoculated in the field. 

 A few minute infections were obtained on Fortunella tnargariia and Fortunella japon- 

 ica during August, 1919. Plants of the oval kumquat, budded on Poncirus trifoliata, 

 were inoculated in the field every week during the growing season of 19 18 with 

 negative results. 

 Microcitrus australasica (Muell.) Swingle {Citrus australasica, Muell.). Finger 



lime (CPB 7600 and 7600B, cuttings and seedlings), I, II, III, and II, in field, 



1917. 

 Microcitrus australasica var. sanguinea Swingle. (CPB 7775B, cutting), II. 

 Microcitrus Garrowayi (Bail.) Swingle {Citrus Garrowayi, Bail.). Garroway's finger 



lime (CPB 11008, cuttings), I, II, III. 

 Microcitrus australis (Planch.) Swingle {Citrus australis, Planch.). Dooja (CPB 



7307 and 7427, cuttings and seedlings), I, II, in field, 1917. 



The last two species have proved to be quite easily infected with canker, but it was not 

 until quite recently that Microcitrus aiistralasica and its variety sanguinea became in- 

 fected. Here infection is limited to a few scattering, small, slow-growing, dark, oily 

 spots with an occasional spot on the thorns and twigs. On M. australis and M. 

 Garrowayi from 30 to 90 per cent of the leaves have tiny, scattering, compact spots 

 (PI. 59, C), which do not penetrate through the leaf. Thorn, twig, and stem infec- 

 tions are also severe, the spots being ruptured and of a girdling type, resembling 



' Included in experiments of March 21, 1918. 



