ORNAMENTALSAND
TURF
ORNAMENTALS
The information and recommendations in this newsletter are applicable to North Carolina and may not apply in other areas.
Japanese beetles and twospotted spider mites are still abundant on
bedding plants and shrubs in the landscape. Second generation
azalea lace bugs are also damaging azaleas and rhododendrons where
they were not controlled earlier.
As field corn dries out and become less suitable for egg laying,
summer generations of yellowish-brown European corn borer moths
oviposit on more than 200 different plants including
chrysanthemums, asters, cosmos, dahlia, gladioli, hollyhocks,
roses, zinnia and some vegetables as well. There may be three
generations of borers per year. The moths first appear in late
spring. Females lay up to 400 eggs in flat masses on the underside
of host plant leaves. The eggs resemble tiny fish scales in shape
and arrangement. The borers hatch and feed on the surface of
leaves for a few days. As the borers mature, they bore into the
host plant stalk to feed. The borers push frass mixed with silk
out of the entrance hole. European corn borer caterpillars are
cannibalistic. This explains why only one or two borers are found
in a pot of mums even though the moth laid dozens of eggs. This
pest overwinters in the stalk as mature larvae, so destroying the
stalks of corn, dahlia, mums and weeds in the area will help to
suppress next season's population. They pupate inside the stalk.
The best pesticides recommendation is a spray with a pyrethroid
such as Talstar, Mavrik, or Tempo 2 every month
or so. After the borers are in the stalk it is essentially too
late, although a desperation spray of Dursban (DuraGuard) could be
tried. Culling and destroying infested stalks in the winter may be
helpful. There is additional information on the biology of the
European corn borer in Publication AG-136, Insect and Related
Pests of Flowers and Foliage Plants. A copy of this North
Carolina Cooperative Extension Service publication should be
available in each county Extension center in North Carolina.
Greenstriped mapleworms are one of the more common caterpillars on
maple although they usually are not a widespread pest.
Occasionally greenstriped mapleworms become locally abundant.
When fully grown, the caterpillars crawl to the soil and dig in to
pupate. A few weeks later, the pupae molt into beautiful pink and
yellow moths called rosy maple moths. These moths then lay masses
of bright yellow eggs from which hatch a second generation of
greenstriped mapleworms. Every few decades, these caterpillars
become abundant enough to cause significant damage to maple. I
have not seen it yet, but older literature refers to episodes in
which the first generation strips the maples bare and then just as
a new flush of growth emerges, the second generation emerges to
defoliate the trees again. This kind of defoliation can seriously
weaken maples to the point that borers may infest the trees and
finish them off. Sevin or some other contact insecticide should
give adequate control. Bacillus thuringiensis should provide
adequate control is it is applied when the worms are small. The
county Extension centers in North Carolina should have a copy of
Ornamentals and Turf Insect Note No. 7 that give some
recommendations for caterpillar control.
The adult green June beetle is an attractive green and gold beetle
that emerges from a pupal cell in the soil and feeds as a chafer on
the foliage and fruit of trees in mid summer. Green June beetle
grubs are unusual in that they sometimes emerge from the soil and
crawl on their backs. Sometimes homeowners find hundreds or
thousands of these large, white grubs on the sidewalks and
driveways around the house. Green June beetle grubs are unusual
also in that they are susceptible to Sevin insecticide applied as
a dust or spray to the surface of the soil or infested turf. The
Sevin should not be watered in. The only complaints heard about
using Sevin for green June beetle control is that it works so well
that the grubs produce a noticeable odor as they decay (if there
are large numbers of grubs present).
Mole crickets have hatched in the Southeastern portion of North
Carolina, Japanese beetles are happily laying eggs in irrigated
turf throughout the state, chinch bugs are getting a foothold in
St. Augustinegrass, cutworms are appearing sporadically across the
state, and millipedes are everything. This is a normal year for
turfgrass.
Web page last updated on July 14, 1997 by Stephen J. Toth, Jr..
