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How to Manage PestsUC Pest Management Guidelines
DESCRIPTION OF THE PESTS Plant parasitic nematodes are microscopic roundworms that feed exclusively on plant tissues. Most species parasitize plant roots. They survive in soil and plant tissues, and several different species may coexist in turf. They have a wide host range, and vary in their environmental requirements and in the symptoms they cause. While the other species occur throughout the state, the sting nematode has only been reported from the Coachella Valley, and the seed and leaf gall nematode has only been found in Monterey and San Francisco Bay areas. DAMAGE
In 1992, sting nematode, a major pest of turf and other commercial crops in the southeastern United States, was collected from several turf sites in the Coachella Valley. Sting nematode feeds on the tips and along the sides of the roots. Activity of this pest is highest in sandy, moist soils when soil temperature is in the 72° to 92°F (22° to 33°C) range. Many golf courses in the Monterey and San Francisco areas with annual bluegrass (Poa annua) greens are infested with the seed and leaf gall nematode. Presence of this nematode is associated with localized yellowing and death of turf on greens. Root knot, spiral, and ring nematode are also commonly present on these courses. Although not proven to be damaging to turf, lesion nematodes are commonly found associated with turfgrasses, stubby root nematode may be found feeding on growing root tips. Additional nematodes associated with turfgrasses in California are: dagger nematodes, Xiphinema sp.; needle nematodes, Longidorus sp.; pin nematodes, Paratylenchus sp.; and sheath nematodes, Hemicycliophora sp. SYMPTOMS
Aboveground symptoms of a severe nematode infestation include patches of yellow plants, stunting, and poor growth. 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. Turf affected by sting nematode exhibits drought and malnutrition symptoms and does not respond to watering or feeding. Badly affected plants collapse and die in patches that can measure up to several feet in diameter. Annual bluegrass infested with the seed and leaf gall nematode will have light-colored swellings or galls at the crown of the plant. Galls contain nematodes of different stages. Mature galls may be filled with hundreds of juvenile nematodes or with bacteria that resembles white cream. Roots of grasses infested with lesion nematodes may exhibit brown-black lesions of various sizes and shapes. Feeding by stubby root nematodes causes swollen and/or discolored root tips and restricts root growth. FIELD EVALUATION In established turf, randomly take several soil cores (1 to 2 inches in diameter) or a cup cutter core to a depth of 4 to 6 inches, from each area of suspected nematode infestation. To allow comparison you may take similar samples from adjacent areas with apparently healthy plants. If only soil is present, randomly take several soil cores to a depth of 6 to 8 inches to make a composite sample of about 1 quart (1 liter) for each area. Place the samples in separate plastic bags, seal them, and place a label on the outside with your name, address, location, the previous crop, and the grass you intend to grow. Keep samples cool (do not freeze), and transport as soon as possible to a diagnostic laboratory. MANAGEMENT Sting Nematode. Turf and soil cannot be removed from Coachella Valley golf courses where sting nematode has been documented without notifying the Riverside County Agricultural Commissioner. Soil samples should only be sent to a laboratory authorized to run quarantine samples. Treatment Decisions. Apply a preplant or postplant treatment if sampling indicates that potentially damaging nematodes are present. When treating established turf, leave a few of the affected areas untreated for comparison if possible.
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UC IPM Pest Management Guidelines: Turfgrass |
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