Cause Mesocriconema xenoplax, an ectoparasite which gets its common name from the cuticular ring ornamentation around its body. The nematode moves slowly as it browses along the root and may feed at one site up to 7 days. It feeds from outside of the root by inserting a stylet into an individual root cortical cell. Ring nematode does not disrupt the cell membrane during feeding, but alters the sink strength of the punctured cell and those cells surrounding it, allowing for greater metabolic activity. Ring nematodes were found in 85% of Oregon vineyards and 82% of Okanagan, BC blocks surveyed but in only 14% of Washington vineyards and 38% of Idaho. Due to low population densities in typical vineyard soils there is little concern that ring nematode will cause significant damage in Oregon vineyards.
Symptoms At high population densities, this nematode can cause extensive root pruning, which stresses the plant and reduces yields. Own-rooted vines are more tolerant of these nematodes.
Sampling Best sampling time west of the Cascade Range is February or March when populations are high and soils are moist and easy to sample. 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. In Washington, 300 nematodes per 250 cc of soil reduced 'Concord' grape yields. In western Oregon, ring nematodes are rarely associated with significant yield reduction in established vineyards. However, this nematode can affect the establishment and yield of young vines.
- Use clean rootstock.
- Use resistant rootstocks. Research trials demonstrated that '420A' was very resistant, '101-14' and '110R' were moderately resistant and 'Riparia Gloire', '3309C' were very susceptible to the ring nematode.
- Avoid sites with previous vineyard or orchard crops.
- Do not over-crop vines.
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 to the point they can tolerate nematode feeding after the chemical's effects dissipate.
- Preplant fumigation. Check labels for buffer zone requirements.
- 1,3-dichloropropene which is available in various formulations including: Telone II (97% 1,3-D), C-17 (17:81% chloropicrin:1,3-D), and C-35 (35:63% chloropicrin:1,3-D). Soil conditions where grapes are grown are often not conducive for optimum performance of this fumigant in the PNW. Check label for rates and proper ground preparation before application. 5-day reentry. Restricted-use Pesticide.
- Dominus at 10 to 40 gal/A. Apply as a shank injection to an entire field or raised beds when soil temperatures are above 60°F but not greater than 90°F. 5-day reentry.
- Metam sodium-generating products such as Basamid G or Vapam HL. Rates will depend on soil type. Converting the active ingredient into the gaseous phase depends primarily on soil moisture and temperature; follow the label carefully. In the PNW, if application is made in the spring wait up to 21 days before planting to avoid phytotoxicity. 5-day reentry. Restricted-use pesticide.
- Postplant chemical use.
- Ecozin Plus at 25 to 56 oz/A through a drip irrigation system. Label suggests using additives to aid penetration into the soil and to make applications in the morning. Efficacy in the Pacific Northwest is unknown. 4-hr reentry. O
- Nema-Q at 1.5 to 3 gal/A for the first application followed by 5 to 10 regular applications at 2 quarts/A. Efficacy in the Pacific Northwest is unknown. 24-hr reentry. O
- DiTera DF (Myrothecium verrucaria strain AARC-0255 fermentation solids and solubles) is registered for many nematodes on grapes. Field and greenhouse tests by the USDA found the product was ineffective for suppressing ring nematode populations. 4-hr reentry. O
- MeloCon WG (Paecilomyces lilacinus strain 251) at 2 to 4 lb/A plus a soil wetting agent can be applied to established plants, although it might be better used when applied to plants just before planting. Stable for only days at room temperature, weeks in the refrigerator or for a year if frozen. Unknown efficacy in the PNW. 4-hr reentry. O
Reference Schreiner, R.P., Zasada, I.A., and Pinkerton, J.N. 2012. Consequences of Mesocriconema xenoplax parasitism on Pinot noir grapevines grafted on rootstocks of varying susceptibility. American Journal of Enology and Viticulture 63:251-261.
Forge, T., Munro, P., Midwood, A. J., Philips, L., Hannam, K., Neilsen, D., Powers, T. and Zasada, I. 2021. Shifting Prevalence of Plant-Parasitic Nematodes in Orchards and Vineyards of the Okanagan Valley, British Columbia. Plant Health Progress. https://doi.org/10.1094/PHP-10-20-0079-RS