Black Turfgrass Ataenius
DISTRIBUTION
Reported from every continental
state except Nevada and Montana.
HOST
Both species prefer the same turf
grass micro habitats and frequently form mixed populations. As
members of the dung beetle sub family, the females are highly
attracted to dung, compost, piles of decaying grass clippings, and
turf thatch. Pest level populations are primarily restricted to
golf courses having a combination of high percentage of annual
bluegrass and high levels of organic matter in the soil profile.
Under these conditions Grubs can damage Fairways, Tees, and
Greens.
Although these two species are ubiquitous in lawns, meadows and woodlands, they rarely attain pest status in these habitats. In all habitats, root feeding may be secondary to organic material consumption. Damage to Annual Bluegrass, Kentucky Bluegrass, Bentgrass and fine fescues has been reported, but 80% of the severe damage is found in the Annual Bluegrass turf.
DAMAGE
Damage is similar to Japanese
Beetle injury. The turf shows localized dry or wilted spots that
over time coalesce into large brown dead areas. The roots are
severed and the dead turf is easily rolled back to expose the
feeding grubs. Turf will not recover from severe damage and looses
will continue under irrigation.
Peak populations in Maryland golf course fairways ranged 150-300 per sq. ft. An infestation of 30-40 grubs per sq ft. will kill annual Bluegrasses and Bentgrass. Kentucky Bluegrass and tall fescues are tolerant of similar populations.
CONTROLS
The preference for high levels of
soil organic matter does present a problem. Dursban and Diazinon
quickly tie up in the thatch and fail to thoroughly penetrate the
soil profile. The accumulation of a thick thatch layer also repels
irrigation water during the summer drought periods. These combined
conditions of thick thatch and high levels of Organic Matter make
grub control extremely difficult with the best insecticide
regardless of irrigation levels. Under these extreme circumstances
many superintendents prefer to control the adults in the spring
before they lay eggs in the thatch. In this situation diazinon or
dursban have the advantage of long residual and concentrating in
the thatch. The females entering the thatch to lay eggs are
quickly controlled by the insecticide.
To determine when adults will begin laying eggs, visually inspect golf greens for adult beetles. The egg-laying period for the first annual generation corresponds to the full-bloom periods of Vanhoutte spirea and horse chestnut, and the first-bloom periods of the black locust. Second generation egg-laying coincides with the blooming of the rose-of-Sharon (Hibiscus syriacus). Observation of these indicators may be used as a basis for applying controls however monitoring adults with a UV-light trap is a more accurate method.
CULTURAL CONTROL
The most successful control
method includes a herbicide program to eliminate the Poa annua.
Replacement with other more tolerant grass species such as
perennial rye, Kentucky bluegrass, zoysia, bermuda or tall fescue
is highly recommended. Bentgrass greens still remain susceptible
but the attractiveness to the female is greatly diminished with
the elimination of annual bluegrass from the golf course.
Elimination of grass clipping pile is also advisable.
BIOLOGICAL CONTROL
A naturally occurring Milky
disease similar to the Japanese Beetle Milky disease has become
established in most areas east of the Mississippi River. Grub
Mortality in the range of 30-90% has been maintained for 7-10
years on many courses that were devastated in the late 1970's and
early 1980's. This milky disease isn't produced commercially but
spreads by natural agents, mostly birds.
CHEMICAL CONTROL
Once the annual bluegrass is
removed and the natural milky disease becomes established,
insecticide controls are usually no longer required. However if
required, the adult insecticide controls in the early spring are
recommended. Under conditions of thick thatch and no irrigation
the adult suppression program is soil more efficacious than the
grub insecticide programs.
by Dr. Lee Hellman, Department of Entomology and Dr. J. Kevin Mathias, Institute of Applied Agriculture