Paras . A : 9 



brown Icnobs closely clustered around vulva. Hyaline portion 

 of larval tail at least one and one-half times longer than 

 stylet Heterodera major 



Cyst with or without punctation, mostly in rows if present; 



brown knobs not closely clustered around vulva. Hyaline 



portion of larval tail about as long as stylet 9. 



9. Average length of lai'vae I4.8O p or more 10. 



Average length of larvae about U6O p Heterodera schachtii 



10. Average length of larvae U8U }i Heterodera glycines 



Average length of larvae 502 ji Heterodera trifolii 



Average length of larvae 5l8 }i Heterodera schachtii 



galeopsidis 



11. H. gOttingiana group. 



Average length of larvae UlU p. Heterodera cruciferae 



Average length of larvae kSh p. Heterodera caret ae 



Average length of larvae UTU p Heterodera g5ttingiana 



Average length of larvae UO^ p Heterodera humuli 



Average length of larvae li06 p Heterodera fici 



Host Plants 



Many lists of host plants of Heterodera species have been published, but 

 it seems probable that many of these are inaccurate in that they include 

 plants which are not hosts of the species discussed. This is especially 

 true of the older lists and of those based on Information compiled from 

 the literature rather than from host tests. In order to avoid this par- 

 ticular error, the following list of hosts includes only the type host, of 

 each species and an indication of the other plants which it attacks so 

 far as there is general agreement or information on host tests available. 

 That is, the list is not intended to be complete, but is believed to be 

 accurate so far as what is included is concerned. 



The species of Heterodera and their principal hosts are: 



H. schachtii . T.'ype host, sugar beet ( Beta vulgaris L.). Also other 

 Chenopodiaceae, many species of Cruciferae (Oostenbrink, 1950 and Jones, 

 1951) and various species of other plant families (Thome 1932). It seems 

 possible that H. schachtii attacks a wider variety of plants than any 



