JOURNAL OF AGRIOHliAL RESEARCH 
Vol. XXVIII Washington, D. C., June 14, 1924 No. 11 
ON SOME PLANT PARASITIC NEMAS AND RELATED 
FORMS 1 
By G. Steiner 
Nematologist, Bureau of Plant Industry , United States Department of Agriculture 
A CEPHALOBUS LIVING IN THE GREEN LEAVES OF PHLOX DRUMMONDII 
PREVIOUS FINDINGS 
Few Cephalobi have been mentioned as infesting plants. De Man (see Ormerod 
IS), 2 found oats appearing as if infested by Tylenchus dipsaci Kuhn, to harbor 
instead many Cephalobus rigidus (A Schneider). Ritzema-Bos ( 15 p. 827) 
observed in Allium proliferum infested with Tylenchus dipsaci and other nemas, 
specimens of Cephalobus rigidus and elongatus de Man. In 1891 (IS) he again 
found two Cephalobus species in the healthy, as well as in the diseased, parts of 
strawberry plants suffering from cauliflower disease, caused by Aphelenchus 
ormerodis, and considered one species closely related to, or identical with, C. 
nanus de Man, and the other with C. rigidus. In some plants the latter was 
more numerous than the Aphelenchus; but since all contained Aphelenchus , 
and only a majority Cephalobus , the origin of the disease was attributed to the 
former. In the first important study of a plant-attacking Cephalobus, 1906 
and 1909, Kati Marcinowgki (8, 10) showed by many experiments that C. 
elongatus enters healthy plants (rye, etc.) and, if numerous, may kill, or at least 
injure, the host plant. 
NEW OBSERVATIONS 
August, 1923, Florence Hedges submitted mature Phlox plants from Quaker 
Neck, Chestertown, Md. The plants were green with only a few brown spots, 
but dwarfed, less bushy, and with fewer flowers than in previous years. Larval 
and adult specimens of Cephalobus were fairly numerous within the green leaves 
and stems of these plants, but not massed. When the leaves were covered with 
water, many nemas soon left them and sank by hundreds to the bottom. 
The Cephalobus proved to be C. subelongatus Cobb (8), a species based on a 
single female. Dr. N. A. Cobb placed at the writer’s disposal a sketch of a male 
tail end, and notes in which this species is mentioned as living on green pepper 
pods, Philippine Islands, on clover seeds, Idaho, and on lily of the valley roots 
(Convallaria majalis ), Washington, D. C. He has also observed C. subelongatus 
on diseased germinating rubber seed (Castilloa) in Hawaii, and in crowns of 
diseased alfalfa plants from New Jersey and Pennsylvania. 
1 Received for publication Jan. 28,1924--issued November, 1924. 
2 Reference is made by number (italic) to “Literature cited,” pp. 1065-1066. 
Journal of Agricultural Research, Vol. .XXVIII, No. 11 
Washington, D. O. June 14, 1924 
Key No. G-470 
96462—24f-1 
(1059) 
