|
Surface/Soil Feeders - Annual Bluegrass Weevil (ABW)
ANNUAL BLUEGRASS WEEVIL (ABW)
aka: Hyperodes weevil
scientific name: Listronotus anthracinus
FIELD KEYS
Hosts: Annual bluegrass
Site symptoms: Wilted turf at short-cut, highly-managed, Poa annua
sites that turn yellow to brown in small to large areas from May to August.
Plant symptoms: Grubs hatch from eggs laid in holes in leaf bases.
They enter and feed on the stem. When sawdust-like frass packs the inside
of the leaf stems, grubs exit to enter new stems. Older grubs exit to
feed at crowns. Adult feeding produces holes in leaves or ragged leaf
edges.
Site keys: Golf courses and recreational sites where Poa annua
is intensely managed at low cutting heights - tees, greens, fairways,
tennis, and lawn bowling facilities
SPECIMEN ID
Immatures are small plump legless white grubs with light brown heads.
Grubs can grow to 1/6 inch. Adults are light brown to black, 1/6 inch
beetles with a beak-like snout that has two elbowed antennae near its
end.
SCOUTING TIPS
Over-wintering beetles become active in early to mid-spring, look for
early signs of feeding in Poa Annua turf areas near trees/shrubs with
litter at base. Affected plant leaves separate easily from crown. Leaves
with stems are hollowed out and frequently filled with frass. Damage may
appear as early as mid-May to as late as early August. Adult feeding and
egg-laying produces small holes in stems and at leaf edges. Adults can
be captured with a sweep net in evening or seen with a light while crawling
on turf at night Soap or insecticidal flushes can be used to dislodge
adults from turf during daylight hours. Look for over-wintering adults
in litter/mulch under trees/shrubs near infestation sites.
CONTROL STRATEGIES
Cultural: Since ABW is only a pest on Poa Annua, either manage
the site to favor existing bentgrass, renovate, or sod heavily infested
areas with bentgrass varieties suited for the site. Where renovation/sodding
is not an option, remove litter/mulch from base of adjacent trees/shrubs.
Chemical: Scout for adults at over-wintering sites in late winter
to very early spring and at vulnerable Poa Annua sites in early to mid-spring,
if chemical control is warranted both the adults and the grubs can be
treated, but at different times - adults in early to mid-spring and mid
to late summer with grubs late spring to mid-summer.
Growth stages: egg - grub (five instars)* - pupa - adult*
* - treatable stages
Life cycle: 1 year cycle
Sequence: adult - egg - grub - pupa - adult
|
