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How to Manage Pests

The UC Guide to Healthy Lawns

Plant-parasitic nematodes

Female root knot nematode

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Identification

Plant-parasitic nematodes are tiny roundworms, 1/50 to 1/16 inch (0.4 - 1.5 mm) long. They feed on plants by inserting a mouth stylet into cells to withdraw nutrients. Soil-dwelling, beneficial nematodes do not have a stylet and cannot feed on plants. Ectoparasitic nematodes occur predominately in soil and feed on the surface of roots while endoparasitic nematodes live and feed mainly inside of plant tissues. Several species of nematodes may be associated with turfgrasses in California. Statewide, root-knot nematodes (Meloidogyne spp.) are the most important nematode pests

Hosts

All turfgrass species

Symptoms

Aboveground symptoms are nonspecific and typically occur as patches of yellow or wilted plants or reduced growth. Drought stress and poor nutrition may accelerate the decline. Belowground symptoms vary with nematode species but in general result in reducing the ability of roots to sustain foliar growth with water and nutrients. Feeding by root knot nematodes results in swellings, called galls, on roots. Severely galled roots may appear malformed and the root system shortened and thickened. Nematode feeding often predisposes the injured roots to fungal and bacterial attack.

Favoring conditions

Plant-parasitic nematodes have become an increasing problem in sodded lawns, especially in irrigated, warm, sandy soils. Runoff water from infested areas such as a neighbor's yard or sharing of contaminated equipment can cause the infestation to spread. Heavy traffic, extremely short mowing heights, and nutrition and water deficiencies also contribute to the problem. Increasing soil temperatures (70° to 86°F ) stimulate nematode activity.

Monitoring information

A laboratory analysis is required to identify the nematodes associated with a problem. In order to establish a potential correlation between nematode presence and observed symptoms, soil and root samples should be collected from both affected and unaffected areas.

Prevention and management

It is virtually impossible to get rid of nematodes once the turfgrass is infested. The key to managing plant-parasitic nematodes is to avoid infestation. Consider seeding rather than sodding, as it is less likely to introduce nematodes to the soil. Reduce stress by aerating and by following proper mowing, fertilization, and irrigation practices for your turfgrass species. There are no nematode resistant turfgrass cultivars. Pesticides for nematode management are not available for home lawns.


Statewide IPM Program, Agriculture and Natural Resources, University of California
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