How to Manage Pests

UC Pest Management Guidelines

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. 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 (Bacillus 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 parasitic 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
Sample for black turfgrass ataenius grubs when irregular dead spots appear in turfgrass and/or about 2 weeks after the adults are identified. 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. (For additional information on monitoring, see GENERAL INFORMATION.) 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
(trade name)		Amount/1000 sq ft**
Many of these products are available for use by licensed applicators only and cannot be used by home gardeners.
A.	CARBARYL*
	(Sevin) 80WSP	6 fl oz
B.	CHLORPYRIFOS
	(Dursban Pro)	3 fl oz
	(Dursban) 50W WSP*	1 oz
	COMMENTS: For use in turfgrass production and on golf courses only. This product is highly toxic to birds and aquatic invertebrates. State and federal agencies have determined that waterways have been impaired by the use of this material. Do not apply in such a manner that it will get into storm water drains.
C.	DELTAMETHRIN
	(DeltaGard T & O) 5SC	0.6-0.9 fl oz
	COMMENTS: To control adults. Not for use on sod farms or in commercial seed production.
D.	HETERORHABDITIS BACTERIOPHORA	25-35 million
	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.
E.	IMIDACLOPRID
	(Merit) 75WP	0.15 oz
	(Merit) 0.5G	1.4 lb
	(Merit) 75WSP	0.15 oz (1 packet/8250 sq ft)
	COMMENTS: 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 (0.18 oz/1000 sq ft). Optimum control will be achieved when applications are made before egg hatch of the target pests followed by sufficient irrigation or rainfall. Applications should not be made when turfgrass areas are waterlogged or soil is saturated with water.
F.	STEINERNEMA CARPOCAPSAE	25 milllion
	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.

**	Apply sprays in 25 gal water/1000 sq ft
*	Permit required from county agricultural commissioner for purchase or use.

PUBLICATION

UC IPM Pest Management Guidelines: Turfgrass
UC ANR Publication 3365-T
Insects and Mites
H. S. Costa, Entomology, UC Riverside
R. S. Cowles, Entomology, Connecticut Agricultural Experiment Station, Windsor, CT
M. A. Harivandi, UC Cooperative Extension, Alameda Co.
J. Hartin, UC Cooperative Extension, San Bernardino Co.
H. K. Kaya, Nematology, UC Davis
Acknowledgment for contributions to the insect and mite section:
K. Kido, Entomology, UC Riverside

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