Cause Meloidogyne hapla, a nematode that lives in soil and attacks many other kinds of plants. Root-knot nematodes are sedentary endoparasites where only second-stage juveniles (the infective stage) and adult males (which may be rare) are found in the soil. The second-stage juveniles penetrate the tips of young roots.
Symptoms Plants look unthrifty and off-color. Roots have large or small galls and the proliferation of adventitious rootlets. May cause severe stunting in sandy soils. Reduced runner production, depressed yields, and shortened life of the planting also occur.
Sampling Take soil samples with sufficient lead time to implement management procedures if necessary. For example, after soil fumigation, it may be several weeks before crops can be planted. Fall sampling for crops to be planted the following spring is an excellent strategy. Include roots and soil in the sample.
Cultural control
- 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. In general, root-knot nematodes have very broad host ranges, therefore, the selection of a non-host cover crop is difficult. 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.
- Rotate using corn or small grains.
- Use certified plants.
Chemical control
- Preplant soil fumigation. Apply in the fall before 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.
- Nimitz at 3.5 to 7 pints/treated A. Incorporated before a minimum of 7 days from planting. Effectiveness reduced on muck or high clay soils. 12-hr reentry.
- 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. 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.
- 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.
Biological control
- Majestene at 4 to 8 quarts/A in sufficient water to thoroughly soak the root zone. Unknown efficacy in the PNW. Has not worked well in potato and raspberry systems. May be used day of harvest. 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 Pinkerton, J.N. and Finn, C.E. 2005. Response of strawberry species and cultivars to the root-lesion and northern root-knot nematodes. HortScience 40:33-38.