| WALNUT ROOTSTOCK | Northern Root-Knot | Southern Root-Knot | Javanese Root-Knot | Peanut Root-Knot | Lesion | Ring |
| Meloidogyne hapla | Meloidogyne incognita | Meloidogyne javanica | Meloidogyne arenaria | Pratylenchus vulnus | Criconemella xenoplax | |
| English | SUSCEPTIBLE, INTOLERANT | SUSCEPTIBLE, INTOLERANT | SUSCEPTIBLE, INTOLERANT | SUSCEPTIBLE, INTOLERANT | SUSCEPTIBLE, INTOLERANT | SUSCEPTIBLE, INTOLERANT |
| Black | SUSCEPTIBLE, TOLERANT | SUSCEPTIBLE, TOLERANT | SUSCEPTIBLE, TOLERANT | SUSCEPTIBLE, TOLERANT | SUSCEPTIBLE, INTOLERANT | SUSCEPTIBLE, INTOLERANT |
| Paradox Hybrid | SUSCEPTIBLE, TOLERANT | SUSCEPTIBLE, TOLERANT | SUSCEPTIBLE, TOLERANT | SUSCEPTIBLE, TOLERANT | SUSCEPTIBLE, INTOLERANT | SUSCEPTIBLE, INTOLERANT |
This chart summarizes the reactions of the nematodes likely to cause problems on walnuts to these rootstocks.
The reactions specified do not always fit with the performance observed in field situations.
English rootstocks are generally observed to be heavily damaged by root knot nematode, while black and paradox are thought of as "resistant". In reality, black and paradox are susceptible and root-knot nematode may be extracted from roots, but the yields may not be affected because the trees are tolerant of the nematodes.
Paradox hybrid is often thought of as being "resistant" to lesion nematode. In reality, populations of lesion nematode on paradox may be as high or higher than on black or English rootstocks. The greater vigor of paradox rootstocks, makes them appear to be less affected by lesion nematode than the other rootstocks. However, a paradox rootstock grown in comparable situations with and without lesion nematode, should demonstrate a more vigorous tree in the situation without nematodes present.