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UC Pest Management Guidelines


Larva of black turfgrass ataenius near lawn grass roots.

Turfgrass

Black Turfgrass Ataenius

Scientific Name: Ataenius spretulus

(Reviewed 9/09, updated 9/09)

In this Guideline:


DESCRIPTION OF THE PEST

The adult black turfgrass ataenius beetle is 0.2 inch (5 mm) long, shining jet black, and has parallel grooves on the wing covers (elytra). Adults can be seen any time of day, especially on golf course greens and tees. Adult black turfgrass ataenius can easily be mistaken for another beetle, Aphodius lividus (not known to damage turf), which is slightly smaller and chocolate brown with straw-colored stripes near the center of the back and along the margin of the elytra.

Female ataenius adults burrow into the thatch and upper soil where they lay clutches of 11 or 12 eggs. Eggs hatch into scarab grubs, which can be distinguished from other white grubs by their small size, the scattered pattern of bristles on the last abdominal segment, and a pair of pads at the tip of the abdomen. At least two or three generations develop in California each year with up to five in the warmest part of the state. Adults are continuously active during warm months in inland areas. They probably overwinter in a reproductive dormancy.

SUSCEPTIBLE SPECIES

Although black turfgrass ataenius is common in many turfgrass areas, it is predominantly a pest of golf courses, especially during summer on highly stressed, cool-season grasses. It is also commonly found damaging bentgrass/rye mixtures and in annual bluegrass.

DAMAGE

The larval stage damages turfgrass by feeding on roots, resulting in irregular dead patches. The damaged area appears to be drought stressed, even where there is sufficient irrigation. Symptoms may resemble those of turfgrass root diseases such as summer patch, take-all patch, and Pythium root rot. Extensive root feeding sometimes allows the turf to be rolled back like a carpet. Digging by vertebrate predators, such as crows, raccoons, and skunks, is a common indication of high grub populations.

MANAGEMENT

Turfgrass can be managed to withstand low levels of black turfgrass ataenius by carefully scheduling irrigations and modifying mowing practices. If sampling indicates the population requires treatment, several treatment choices are available, including the use of parasitic nematodes.

Biological Control
Milky spore (Paenibacillus spp.) organisms have been detected infecting black turfgrass ataenius in California. Milky spore pathogens affecting ataenius do not include the one that controls Japanese beetles and are not commercially available. When black turfgrass ataenius is infected with milky spore diseases in other geographical areas, it undergoes a 3- or 4-year boom-and-bust cycle at a site, then the site becomes protected for several years from further damaging populations because of the milky spores presence in the soil, but this has not yet occurred in California. For short-term control, the pathogenic nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora are often effective.

Cultural Control
Improve root development as much as possible to allow turfgrass to withstand grub feeding by following recommended irrigation practices based on evapotranspiration needs of turfgrass, using small-tine or water injection aeration, and raising mowing height as feasible.

Monitoring and Treatment Decisions
The most effective insecticides, the neonicotinoids such as imidacloprid, provide best control if applied to just before adults lay eggs, generally before serious damage is seen. However, damaging infestations are not common and treatment is not regularly required, so this preventive approach is not recommended where an infestation is not expected. These materials can also be effective against very young grubs.

If irregular dead spots appear in turfgrass, sample for black turfgrass ataenius grubs or other insects. You can also sample about 2 weeks after adults are caught in black light traps. Use a cup cutter to sample for grubs underneath areas of turfgrass damage and in areas where grubs have been active in the past or are likely to occur (collars, wet spots, black layer spots). Grubs will be present at the thatch/soil interface. If there are more than four grubs per cup cutter sample (or 40 grubs per square foot), treatment is necessary. Threshold levels are much lower for bentgrass grown in the desert region than the rest of the state because of the heat and drought stress. Apply liquid sprays or nematode applications to moist turfgrass and granules to dry turfgrass. Irrigate following application to move the material into the zone of larval feeding.

Common name Amount/1000 sq ft** Ag Use
R.E.I.+
NonAg Use
R.E.I.+
(trade name)   (hours) (hours)

  Calculate impact of pesticide on air quality
The following materials are listed in approximate order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and the environment. Not all registered materials are listed. Not all registered pesticides are listed. Always read label of product being used.
 
A. IMIDACLOPRID
  (Merit) 75WP 0.15 oz 12 until dry
  (Merit) 0.5G 1.4 lb 0 0
  (Merit) 75WSP 0.1939 oz 12 until dry
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: Optimum control will be achieved when applications are made before egg hatch followed by sufficient irrigation or rainfall. Use in areas that have had severe infestations of black turfgrass ataenius in the past. Maximum of 1 application/year. Applications cannot exceed 8.6 oz/acre/year (0.19 oz/1000 sq ft). Applications should not be made when turfgrass areas are waterlogged or soil is saturated with water.
 
B. HETERORHABDITIS BACTERIOPHORA 25–35 million NA NA
  COMMENTS: Store nematodes properly before use as directed. Apply to warm, moist, but not soggy soil. Several irrigations may be needed during 2 weeks after application to keep soil moist. Apply during the coolest time of day in hot areas.
  . . . or . . .
  STEINERNEMA CARPOCAPSAE 25 million NA NA
  COMMENTS: Store nematodes properly before use as directed. Apply to warm, moist, but not soggy soil. Several irrigations may be needed during 2 weeks after application to keep soil moist. Apply during the coolest time of day in hot areas.
 
C. ACEPHATE
  (Orthene, Pinpoint) Label rates 24 until dry
  MODE OF ACTION GROUP NUMBER1: 1B
  COMMENTS: Make two biweekly applications when larvae detected. For use on golf courses and sod farms only. Odorous.
 
** Apply sprays in 25 gal water/1000 sq ft.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
+ 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. Agricultural use applies to sod farms and commercial seed production.
NA Not applicable.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Turfgrass
UC ANR Publication 3365-T
Insects and Mites
M. L. Flint, UC IPM Program, UC Davis
M. A. Harivandi, UC Cooperative Extension, Alameda County
H. K. Kaya, Nematology, UC Davis
Acknowledgment for contributions to Insect and Mites:
J. Hartin, UC Cooperative Extension, San Bernardino County
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
K. Kido, Entomology, UC Riverside
H. S. Costa, Entomology, UC Riverside
D. D. Giraud, UC Cooperative Extension, Humboldt/Del Norte counties

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