Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Strawberry -- Nematode (Root-lesion)
 
Cause: Pratylenchus penetrans and P. crenatus, nematodes that live in soil. Legumes such as clover, alfalfa, and vetch often harbor large populations of root-lesion nematodes which may affect future strawberry plantings. The number of nematodes in the soil can be a rough guide to possible plant damage. Factors such as crop age, planting frequency, presence of other diseases and pests, and adverse growing conditions influence the effect of certain nematode populations on plant growth. In some cases, 300 nematodes/quart of soil affect plant growth, but much higher populations often have little effect. Root-lesion nematodes are migratory endoparasites (see Nematodes); part of the population is in soil and part in the roots at all times.
Symptoms: Infected plants are dwarfed, off-color, and grow poorly. Damage is frequently seen as spots in the field. Roots have brown lesions.

Note the necrotic areas on these strawberry roots caused by the lesion nematode.

Heathy root system on the right and high nematode populations affecting the root systems in the middle and left.

 
Sampling: Always include soil and roots in samples sent for nematode analysis if plants are present. Take samples any time if the numbers are interpreted in relation to nematode population dynamics. In most crops, populations are relatively low through winter and spring but increase rapidly through summer. Before planting strawberries, it is best to sample in late summer.
Cultural control:

  1. If possible rotate plantings to new land.
  2. Use certified plants.
Chemical control: Preplant soil fumigation.

  1. Basamid G. Avoid application when soil is over 90 F. Do not apply within 3 to 4 feet of growing plants. Do not harvest within one year of application. 24-hr reentry plus ventilation.
  2. Methyl bromide + chloropicrin (33 to 55%) under polyethylene film. See label for rates. Restricted-use pesticide.
  3. Telone II at 24 to 36 gal/A broadcast on mineral soils. Wait 2 to 3 weeks after treating to plant, or until odor leaves the soil. Do not treat extremely heavy soils. 5-day reentry. Restricted-use pesticide.
  4. Telone C-17 at 27 to 41 gal/A broadcast on mineral soils. Wait 2 to 3 weeks after treating to plant, or until odor leaves the soil. Do not treat extremely heavy soils. 5-day reentry. Restricted-use pesticide.
  5. Vapam (32.7% metam sodium) at 50 to 100 gal/A. Immediately roll the soil and follow up with tarps or a light watering. May use through an irrigation system. 48-hr reentry and/or while tarps are being removed.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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