Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Grape -- Nematode (Dagger)
 
Cause: Xiphinema americanum, has been found in 85% of the vineyards surveyed in western Oregon, while X. pachtaicum, and/or X. americanum were found in 74% of eastern Washington vineyards. Only X. americanum is known to be a vector of Tobacco ringspot virus and Tomato ringspot virus which have been reported occasionally on grape in the Pacific Northwest. Dagger nematodes are migratory ectoparasites (see Nematodes) found only in soil. As virus vectors they can be damaging at very low population levels. Dagger nematode populations may be very low in late summer when other nematodes are abundant.
Symptoms: Enlarged root tips and feeder roots may occur which could result in a witches' broom effect on the root. Yields may be reduced when nematode populations reach high levels.
Sampling: The best time to sample for dagger nematodes west of the Cascades may be the same as for blueberry or raspberry where populations peak from February to April. If planting grapes, sample during this period to increase the probability of detecting dagger nematodes if they are present. In eastern Washington, the best time to sample is at the end of the growing season when populations are highest. Take samples 1 ft from the vine and in the vine row. Remove the top 2 to 3 inches of soil and sample 1 ft deep with a soil tube 1 inch in diameter. Take 10 to 20 subsamples in a given area and combine into one sample. Yield loss in eastern Washington has been associated with population densities greater than 25 X. pachtaicum per 250 cc of soil. No significant yield losses have been observed for X. americanum in established Oregon yineyards.
Cultural control: If the virus is not present, the nematode by itself may not be a problem.

  1. Practice good weed control to prevent virus introduction and/or spread.
  2. Plant only virus-tested (and found to be free of all known viruses) rootstock and/or scion.
Chemical control: The key in managing nematodes on perennial crops such as grape is to protect new roots from nematode feeding. This allows roots to establish and to the point they can tolerate nematode feeding after the chemical's effects dissipate.

  1. Preplant fumigation.
    1. Basamid G. Avoid application when soil is over 90 F. Do not apply within 3 to 4 feet of growing plants or closer than the drip line of larger plants. Do not harvest within one year of application. 24-hr reentry plus ventilation.
    2. Metam sodium products such as Vapam. 48-hr reentry.
    3. Telone II up to 55 gal/A in mineral soils. Soil conditions where grapes are grown are often not conducive for optimum performance of this fumigant. Check label for proper ground preparation before application. 5 day reentry. Restriced Use Pesticide.
  2. Enzone can be used through low volume irrigation systems. Use 5 to 30 gal/A/treatment for established vineyards or 20 to 60 gal/A/treatment before planting. Soil temperature must be above 58°F at 6 inches and plants must be established for at least 1 year before treatment. Several applications to an existing vineyard are recommended on the label. Do not apply within 2 weeks of harvest. Oregon and Washington only. 4-day reentry.
Content edited by: John Pinkerton and Jay W. Pscheidt on January 1, 2009
 
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