Northwest berry Foundation

Management Detail

Root-lesion Nematode

in Raspberries

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Latin name: Pratylenchus spp.


Reason for Concern:
1) Nematodes, when present in large numbers, cause stunting and reduce vigor by feeding on the roots.
2) Dagger nematodes can transmit viruses, such as tomato ringspot.

Usual symptoms are areas of distorted or stunted plants. Most nematodes are microscopic though a few species can be seen without magnification. Most plant-parasitic nematodes range in size from 0.02” to 0.04” in length. A great many nematodes have a wormlike or eel like shape. Females of some kinds grow swollen at maturity and resemble tiny beans, lemons, or pears.

Nematodes commonly have 6 developmental phases including an egg, four juvenile stages, and an adult nematode stage. Each juvenile stage is completed by a developmental process called a molt. Except for size, juveniles usually resemble adults. Reproductive organs normally do not appear until after the nematode has undergone four molts. Nematodes are present and active in the soil all year, although the level of activity will be the least in winter when soils are cold.



  • Nematodes have contagious or clumped distributions.
  • Sample field in 2-5 acre blocks (max).
  • Partition fields by soil type, stand vigor, drainage, crop history & etc.
  • Collect 20 core (minimum) to depth of 10”—12” per block.
  • Preplant sampling systemically in each block, “W” pattern is good.
  • Sample established plantings in the plant row or hill and within 12-15” of the crowns, sample systematically throughout the block.
  • Send labeled samples to laboratory for testing.

Cultural Controls:

None listed at present.


For information about chemical controls, check with our Pesticide Guide.


photo from Oregon State University

Root lesion nematode head - photo from Oregon State University


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