Host: a plant that will support the feeding and reproduction of a nematode species. Example: English walnut, Juglans regia, is a host for Pratylenchus vulnus.
Susceptible: the relationship between a plant and a nematode species when the plant will support feeding and abundant reproduction of the nematode and may be subject to damage. Example: Juglans regia is susceptible to Pratylenchus vulnus.
Resistant: describes the effect of the plant on nematode reproduction. Usually infers that some (maybe most) varieties or cultivars of that plant species are susceptible. There may be different levels of resistance among cultivars. Example: the Prunus rootstock Nemaguard is resistant to Meloidogyne incognita , however, it is susceptible to Criconemoides xenoplax.
Vertical resistance may be indicated when a variety differs
in susceptibility to races, implying one or a few genes involved.
May select for races or biotypes of the nematode that are able to overcome
the resistance mechanism. Example: Mi is a single dominant gene
that confers resistance to Meloidogyne
incognita in tomato, Lycopersicon esculentum.
Single-gene resistance against soybean cyst nematode (Heterodera glycines) in soybeans.
Horizontal resistance (multigene) when resistance to races or biotypes of the nematode species is uniform - reduces selection pressure. Example: resistance to Globodera pallida in the potato relative Solanum vernei.
Immune: describes a cultivar or variety of plant that will not support feeding or reproduction of the nematode species. Example: Dog Ridge rootstock (Vitis champinii) of grape is immune to Meloidogyne javanica.
Non-host: usually used when no varieties or cultivars of a plant species support the feeding and reproduction of a nematode species. Example: Citrus spp. are non-hosts to the potato cyst nematode, Globodera rostochiensis.
Tolerant: a host plant that can support reproduction of the nematode while sustaining little damage. Example: the grape (Vitis vinifera) variety "Thompson Seedless" is quite tolerant to Meloidogyne incognita.
Intolerant: a host plant that is heavily damaged at relatively low population levels of a nematode species. Example:
Compatible: interaction between a nematode species and host plant that is favorable to nematode reproduction.
Incompatible: interaction between a nematode species and host plant that is unfavorable to nematode reproduction. An alternative description of the resistant condition.
Hypersensitivity: the condition in which host plant cells die in response to nematode stimulus rather than develop into a feeding site; a mode of resistance that occurs in several plant species. Note, the mechanism underlying the hypersensitive response probably varies among plant species. Example: resistance of potato to Globodera rostochiensis conferred by the H1 gene from Solanum andigena.