H. 'I'gxon: 'j 



brovm knobs 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 larvae U8O p. or more 10. 



Average length of larvae about h60 ^ ijeterodera schachtii 



10. Average length of larvae U8U p Heterodera glycines 



Average length of larvae 502 y Heterodera trifolii 



Average length of larvae 5l8 yi Heterodera schachtii 



galeopsidis 



11. H. gBttingiana group. 



Average length of larvae UlU V- Heterodera cruciferae 



Average length of larvae )4?U ^ Heterodera carotae 



Average length of larvae U7U }i ileterodera gbttingiana 



Average length of larvae U05 ^ Heterodera humuli 



Average length of larvae [1O6 ji 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 froia 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 ar:; wnat is included is concerned. 



The species of ifctero^iera and their principal hosts are: 



H. schaciitii . Type host, sugar beet ( Beta viilgaris L.). Also other 

 Chenopodl/iceae, man.v species of Cruciferae (Oostonbrink, 19?0 and Jones, 

 1951) 'inf^ various npecies of other plant fnuiilios (Thoi-ne IPB^'). It seems 

 possible that )l. schncntij, attacks a wider varjctv <^\^ plniit.s than any 



