|Northern root-knot nematode (Meloidogyne
hapla) infests both peppermint and spearmint, but spearmint appears to be more
tolerant. Northern root-knot nematodes are typical sedentary
endoparasites, which invade root tissue soon after hatching and then establish a
permanent, stationary feeding location. Eggs overwinter in the soil and in live or
decaying root tissues.
||Northern root-knot nematodes may cause
only slight damage the first growing season, but severe damage may occur in subsequent
seasons as populations increase. Presence of root-knot nematodes in peppermint is
important to growers planning to rotate from mint into potato, since these nematodes will
make tubers unmarketable if they are not managed properly.