Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Raspberry -- Nematode (Root-lesion)
 
Cause: Root-lesion nematodes (Pratylenchus penetrans and P. crenatus) are migratory endoparasites (see Nematodes); part of the population is in soil and part in the roots at all times. Populations in raspberry generally are low through winter and spring, increase rapidly through the summer, and decline in fall. P. penetrans is considered the more damaging of the two. Densities at or below detectable levels at planting can increase to damaging levels by the sixth to eighth year.
Symptoms: Infected plants are dwarfed, off-color, and grow poorly. Foliage may be dwarfed and yellow. Dead roots or lesions may be on roots. Injury is most severe on small feeder roots, which may be completely girdled. Symptoms are most often observed on fruiting canes.

The reddish long structures are the stained bodies of the nematodes in this raspberry root.

 
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. Before planting raspberry, it is best to sample in late summer so the soil may be fumigated in fall.

If soil with more than 100 P. penetrans/500 cc soil (20/100 g soil) is not treated at spring planting, sample the field annually and treat if populations reach damaging levels. Populations over 500 nematodes/500 cc soil (100/100 g soil) at planting will affect stand establishment, first-year growth, and yield. In established plantings, densities of 1,000 to 4,000/500 cc (200 to 800/100 g soil) will decrease plant growth and should be treated. Damage may occur at lower densities if plants also are stressed by diseases, insects, or other factors.

Cultural control:

  1. Use certified planting stock.
  2. Plant in soil free of high populations of root-lesion nematodes.
Chemical control:

  1. Preplant soil fumigation the fall before spring planting.
    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. Restricted-use pesticide.
    3. Telone II at 52 to 103 fl oz/1,000 ft of row using a single chisel per row 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. 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 be used through an irrigation system. 48-hr reentry and/or while tarps are being removed.
References:
Lolas, M.A., K.J. Merrifield, J.K. Pinkerton, and R.E. Ingham. 1992. Effect of fenamiphos on population dynamics of Pratylenchus penetrans and Xiphinema americanum in Oregon red raspberry. Journal of Nematology 24:604-605.

McElroy, F.D. 1992. A plant health care program for brambles in the Pacific Northwest. Journal of Nematology 24:457-462.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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