UC IPM Online UC ANR home page UC IPM home page

UC IPM Home

Search

SKIP navigation
How to Manage Pests

Home & garden
Agriculture
Natural environments
Exotic & invasive

Weather data & products
Degree-days
Interactive tools & models

Identification Galleries

Natural enemies
Weeds

Educational Resources

Publications & more
Workshops and events
Training programs
Pesticide information

Research and IPM

Grants programs
Funded-project results

 
  Printer-friendly version

How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Root lesion nematode adults and eggs.

Cucurbits

Nematodes

Scientific Names:
Root knot nematode: Meloidogyne incognita and M. javanica
Lesion nematode: Pratylenchus spp.
Stubby root nematode: Trichodorus sp. and Paratrichodorus sp.
Needle nematode: Longidorus africanus

(Reviewed 11/05, updated 6/08)

In this Guideline:

DESCRIPTION OF THE PESTS

Nematodes are microscopic roundworms that live in soil and plant tissues. Plant parasitic nematodes feed on plants by puncturing cells and sucking their contents with a needlelike mouthpart called a stylet. They have a wide host range, vary in their environmental requirements, and in the symptoms they cause.

DAMAGE

Root knot nematodes can cause substantial damage to cucurbits. All cucurbits are susceptible to root knot nematodes. Damage is typically greatest in warm regions with light, sandy soils. Nematode-infested plants may have reduced growth, lower yield and fruit quality, and tend to wilt earlier under moisture stress. Lesion nematodes have not been found to cause economic damage in California, but the root lesions formed by their feeding may be invaded by fungi and bacteria. Stubby root nematode can reduce root growth. Pin nematode, Paratylenchus sp., is found in fields but is not known to cause damage to cucurbits in California. Needle nematode has been found to cause damage to cucurbits in the Imperial Valley.

SYMPTOMS

The symptoms described below may be indications of a nematode problem, but are not diagnostic as they could result from other causes such as diseases, insect injury, or nutrient deficiencies. Infestations by root knot nematodes produce characteristic swelling of roots, called galls. Aboveground symptoms for all nematodes include patches of stunted, yellowed, and/or wilted, dying plants. Lesion nematode infestation may cause reddish brown to dark brown lesions on roots. Symptoms due to stubby root nematode infestation include restricted root growth with reduced feeder roots, stunting, and yellowing of plants. Needle nematode causes stunting, terminal root swelling, cessation of root elongation, and root necrosis.

FIELD EVALUATION

It is critical to know the nematode species present and their population estimates to make management decisions. If a previous field or crop had problems caused by nematodes that are listed as pests of cucurbits, population levels may be high enough to cause damage to seedlings. If nematode species have not previously been identified, soil samples should be taken and sent to a diagnostic laboratory for identification.

Soil samples should be taken from within the root zone (6 to 18 inches deep). Divide the field into sampling blocks of not more than 5 acres each, that are representative of cropping history, crop injury, or soil texture. Take several subsamples randomly from a block, mix them thoroughly, and make a composite sample of about 1 quart (1 liter) for each block. Place the samples in separate plastic bags, seal them, and place a label on the outside with your name, address, location, and the current/previous crop and the crop you intend to grow. If plants with symptoms are available, place the roots in the same bag with the soil. Keep samples cool (do not freeze), and transport as soon as possible to a diagnostic laboratory. Contact your farm advisor for more details about sampling, to help you find a laboratory for extracting and identifying nematodes, and for help in interpreting sample results.

MANAGEMENT

Cultural practices. Rotation with nonhost crops can reduce nematode population levels, but it is difficult because of the wide host range of root knot nematodes. Deep plowing, fallow, and destruction of susceptible weed hosts can reduce nematode population levels. Proper irrigation and nutrition reduces stress and may minimize nematode damage.

Resistant cultivars.
None available.

Monitoring and Treatment Decisions.There are no current treatment guidelines for lesion, stubby root or needle nematodes, but if root knot nematodes are present, treat.

Common name Amount/Acre R.E.I.+ P.H.I.+
(trade name)   (hours) (days)
PREPLANT
A. 1,3-DICHLOROPROPENE*/CHLOROPICRIN*
  (InLine) Label rates 7 days NA
  COMMENTS: Multipurpose liquid fumigant for the preplant treatment of soil to control plant-parasitic nematodes, symphylans, and certain soil-borne pathogens using drip irrigation systems only. Use of a tarp seal is mandatory for all applications of this product. Fumigants such as 1,3-dichloropropene are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.
 
B. 1,3-DICHLOROPROPENE*
  (TELONE EC) Label rates 7 days NA
  COMMENTS: Liquid fumigant for the preplant treatment of soil against plant-parasitic nematodes and certain other soil pests in cropland using drip irrigation systems only. Fumigants such as 1,3-dichloropropene are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.
 
C. CHLOROPICRIN* 300–500 lb 48 NA
  COMMENTS: If treated area is covered with a plastic tarpaulin immediately after application, dosage may be reduced.
 
D. METAM SODIUM*
  (Vapam, Sectagon) Label rates 48 NA
  COMMENTS: Contact your farm advisor for advice on the most effective application method for a particular situation. Fumigants such as metam sodium are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.
 
E. ETHOPROP*
  (Mocap) 15% Granular 2.1 lb/1000 row feet (12-15 inches wide) 72 NA
  COMMENTS: Registered for use on cucumbers only. Apply just before planting. Mix into the top 2-4 inches of soil right after application. Do not allow the granules or spray to contact the seed. Make only one application per crop.
 
F. 1,3-DICHLOROPROPENE*
  (TELONE II) Label rates 7 days NA
  COMMENTS: Do not disturb the soil for at least 7 days after application. Fumigants such as 1,3-dichloropropene are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.
 
PREPLANTAND PLANTING
A. OXAMYL*
  (Vydate L) 1–2 gal 48 1
  COMMENTS: To control lesion and root knot nematodes, except Meloidogyne javanica. Rate is for broadcast application. For band treatment, use proportionately less. After application and before planting, incorporate 2–4 inches. Registered on cucumber, cantaloupe, honeydew melon, watermelon, squash, and pumpkin.
 
POSTPLANT
A. OXAMYL*
  (Vydate L) 2–4 pt 48 1
  COMMENTS: Apply in sufficient water to obtain uniform coverage of foliage. Make the first application 2–4 weeks after planting and repeat 2–3 weeks later. Most effective if preceeded by a preplant or planting application. Registered on cucumber, cantaloupe, honeydew melon, watermelon, squash, and pumpkin.
 
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
* Permit required from county agricultural commissioner for purchase or use.
NA Not applicable.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Nematodes
B. B. Westerdahl, Nematology, UC Davis
J. O. Becker, Nematology, UC Riverside
Acknowledgment for contributions to Nematodes:
U. C. Kodira, Nematology, UC Davis

Top of page

Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2008 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See How to manage pests, or in the U.S., contact your local Cooperative Extension office for assistance. /PMG/r116200111.html revised: June 30, 2008. Contact webmaster.