Cause Meloidogyne hapla, root-knot nematodes, are sedentary endoparasites, and only second-stage juveniles (the infective stage) and adult males (which may be rare) are in soil.
Symptoms Roots (tubers) appear lumpy, with necrotic areas up to 0.25-inch deep below the lumpy surface. Dahlias infested with M. incognita have galls on feeder and secondary roots. Root systems were reduced and plants were stunted and of low vigor.
Sampling Take soil samples well before planting to implement management procedures if necessary. It may be several weeks before crops can be planted after soil fumigation. Fall sampling for crops to be planted the following spring is an excellent strategy. When sending samples for diagnosis, include roots as well as soil.
Cultural control
- Select and plant only nematode-free dahlia tubers.
Chemical control Preplant soil fumigation.
- Telone II is registered at various rates depending on planting depth and soil type. See label for details. 5-day reentry. Restricted-use pesticide.
Reference Anwar, S.A., and Javed, N. 2010. Meloidogyne incognita infecting Dahlia. Pakistan Journal of Zoology 42:348-350.