I','irn;j. K:l 



DAHGER NEMTODES (XIPHINEM SPP.) 



The penus Xiphlnema Cobb, 1913j is comprised of several species and is 

 a member of the subfamily Longidorinae and family Dorylaimidae of the 

 Class Aphasmidia. 



The status of this genus as a plant-parasitic group has been recently 

 reviewed by Schindler (1957 s.) , who has done work demonstrating the 

 pathogenicity of X. diver sic auda turn (Micoletzky, 192?) Thorne, 1939, 

 on various hosts TSchindler, 195^, 1957j Schindler and Braun, 195?) • 

 X. americanum is a form commonly encountered in the southeastern United 

 States. It is found, sometimes in large numbers, in soil from such 

 crops as tobacco, cotton, oats, vetch, peach, boxwood, and azaleas. 

 This species is believed to also be an ectoparasite of roots and to 

 cause damage under certain conditions. Although not yet demonstrated 

 under controlled conditions to be pathogenic, various species have been 

 found under circumstances strongly indicating the likelihood of a patho- 

 genic role. Biennial and perennial plants would appear to be hosts most 

 likely to show eventual damage because of large numbers of the nematodes 

 are required to produce appreciable damage. 



Galling of rose, peanut, and strawberry root tips has been reported 

 (Schindler, 195U) for X. diver s ic auda turn and is characteristic enough 

 on these hosts to be given the name of "c\irly-tip." Characteristically, 

 an enlargement of the tip and a curling of the end of the root is pro- 

 duced with apparent necrosis and shriveling of the proximal portion* 

 These galls are somewhat similar to those caused by root-knot nematodes 

 but differ in that they almost invariably involve the distal portion of 

 the root. There are some other aspects concerning the pathogenicity of 

 X. diversicaudatum which Schindler, 1957, points out as being worthy of 

 further investigation. 



A steadily growing list of species exists for this genus; forms being 

 reported from various countries and in association with various kinds of 

 plants. There are two recent taxonomic studies of the group (Lordello, 

 1955, and Luc, 1958). Keys from both of these papers are taken for in- 

 clusion in the Notes because the later paper by Luc does not contain all 

 the forms contained in the paper by Lordello. Another important earlier 

 paper containing illustrations of species of Xiphinema known up to that 

 date is the monograph by Thorne (1939). 



