ORNAMENTALSAND
TURF
ORNAMENTALS
The information and recommendations in this newsletter are applicable to North Carolina and may not apply in other areas.
Glenn Hackney of the North Carolina Department of Agriculture's
Biological Control Laboratory is trying to collect data on the ash
whitefly and a tiny parasitic wasp that attacks the ash whitefly.
The ash whitefly has caused severe damage to pear and apple in
Europe and has caused some misery for landscapers in California
where it was first discovered in 1988. Immature ash whiteflies are
tiny (1 to 2 mm) scale-like insects with unusual lollipop-shaped
setae around the edges and fluffy, white blobs of wax on top. It
was discovered in North Carolina in November, 1993. Heavy
infestations cause leaves to wilt and to drop prematurely. This
whitefly infests catalpa, redbud and other legumes, crape myrtle,
magnolias and tulip trees, all the true ashes, ligustrum, lilac,
pomegranate, buckthorn, crown of thorns, serviceberry, quince,
hawthorn, loquat, crabapple, apricot, plum, peach, choke cherry,
pyracantha, buttonbush, and citrus. Fortunately, there is a
powerful chemical tool to control this pest; Morestan/Joust
(oxythioquinox) is labeled for whiteflies on "trees, shrubs and
flowers" outdoors. If you discover whiteflies on trees and
shrubs, please contact Jim Baker or
Glenn Hackney.
Lloyd Garcia, an entomologist with the North Carolina Department of
Agriculture's Plant Protection Section, has passed along some
information on the Asian maple borer, Anoplophora glabripennis, a recently introduced
longhorned beetle that attacks and kills maples and horsechestnuts.
In China, it attacks elms, poplars, willows and fruit trees. At
this time, the beetle seems to be confined to New York, but it is
important to try to limit the spread of this very damaging insect.
Any suspicious beetles should be submitted to the Plant Disease and
Insect Clinic at North Carolina State University or to any of the
personnel of the North Carolina Department of Agriculture's Plant
Protection Section (telephone: 919-733-0461). The beetles make 3/8
inch holes when they bore out and sawdust collects around the base
of the tree or in crotches where limbs meet the main stem.
The wool sower gall is a distinct and unusual plant growth induced
by the secretions of the grubs of a tiny gall wasp, Callirhytis
seminator. If a fresh wool sower gall is held in a plastic bag out
of the sun (so it will not get too hot), within one to three weeks
the tiny, harmless gall wasps will emerge. The wool sower gall is
specific to white oak and only occurs in the spring. Pulling the
gall apart exposes small seed-like structures. The gall wasp grubs
develop inside these structures. (This gall is also called the oak
seed gall.) Fortunately, wool sower galls are hardly ever abundant
enough to cause harm to white oaks. If the galls are actually
damaging the trees, the best time to control them is mid-winter
when the wasps are laying their eggs or spring just as the buds are
breaking. The eggs hatch just as the new growth emerges in spring.
Orthene or another contact insecticide should give adequate
suppression of these insects. However, by the time the galls are
noticed, it is too late to effectively control the gall wasps.
Gall wasps invariably have alternation of generations in which one
generation develops in one kind of gall (leaf gall) and their
offspring develop in another kind of gall (stem gall). Wasps of
each alternate generation are slightly different is size and the
galls of each generation are enormously different from the parents.
The wool sower gall is probably the leaf gall of this species
because of its transient nature. Ornamentals and Turf Insect Note
No. 5 provides additional information on galls. A copy of the
note is available from county extension centers in North Carolina.
Web page last updated on May 12, 1997 by Stephen J. Toth, Jr..
