Cause Xiphinema americanum and related species are vectors of Tomato ringspot virus. Dagger nematodes are migratory ectoparasites 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 In the absence of the virus, the nematodes may cause sunken reddish brown lesions on roots. Feeding can reduce the root system, which can stunt growth and reduce runner production.
Sampling Best sampling time for dagger nematodes in raspberry is December to April and probably is the same for strawberry.
- Use certified planting stock.
- Plant on soil tested and found free of dagger nematodes.
- In areas with dagger nematodes, consider planting tolerant or resistant cultivars such as Northwest.
- Fallow periods can disrupt the nematode life cycle. Practice good weed control using herbicides or tillage.
- Cover crops are an excellent way to disrupt the nematode life cycle. Care should be taken when selecting a cover crop to avoid use of a plant that is a host for the target nematode. Dagger nematode has a narrow host range so there are more cover crop options available to manage this nematode. Part of an effective cover crop is good weed control. Yellow mustard (Brassica juncea) contains allyl isothiocyanate, which is active against nematodes. Brassica carinata also has been reported to be effective against nematodes.
- Preplant soil fumigation is best for controlling this nematode. Apply in fall for planting the next spring.
- Basamid G. Avoid application when soil is over 90°F. Do not apply within 3 to 4 feet of growing plants. 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.
- Paladin at 25 to 51.3 gal/A. Buffer zone from 35 to 690 feet depending on the rate used and acreage treated. 2- to 5-day entry-restriction period. See label for details. Restricted-use pesticide, Washington only.
- Telone II at 27 to 35 gal/A broadcast on mineral soils. Leave the soil undisturbed for at least 7 days after application. A longer interval, such as 2-3 weeks, is required if soils are cold or wet, or the site will be replanted with deep rooted trees, shrubs or vines. Odor indicates fumigant presence; do not plant until odor leaves the soil. Do not treat extremely heavy soils. 5-day reentry. Restricted-use pesticide.
- Telone C-17 at 27 to 41 gal/A broadcast on mineral soils. Wait 2 to 3 weeks after applying to plant, or until odor leaves the soil. Do not treat extremely heavy soils. 5-day reentry. Restricted-use pesticide.
- Vapam HL at 37.5 to 75 gal/A. Immediately roll the soil and follow up with tarps or a light watering. May use through an irrigation system. 5-day reentry. Restricted-use pesticide.
- Ecozin Plus at 25 to 56 oz/A is registered for use after planting 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 4 to 6 weekly applications at 2 quarts/A. Efficacy in the Pacific Northwest is unknown. 24-hr reentry.
- Velum Prime at 6 to 6.5 fl oz/A can be used after planting using drip, trickle of micro-sprinklers. May be applied day of harvest. Group 7 fungicide. 12-hr reentry.
Reference Nemec, S., and Malek, R. B. 1975. Effects of nematicides and strawberry growth on nematodes, especially Xiphinema americanum, in root-rot sites in Illinois. Journal of Nematology, 7:328.