ORNAMENTALSAND
TURF
ORNAMENTALS
The information and recommendations in this newsletter are applicable to North Carolina and may not apply in other areas.
Green June beetles and Japanese beetles are still pestering rose
growers and other horticulturists. Soon we should see bluewinged
wasps (Scolia dubia) and other beetle grub parasites flying over
the turf. Cicadas are singing and cicada killer wasps and
cowkillers are also present (see the August 8, 1997 North Carolina Pest
News). Keep watching for spider mites. It is also time to start
preparing to apply insecticides for peachtree borers.
There are many species of leafhoppers and leafhoppers are sometimes
quite abundant. Aside from their direct damage to ornamental
plants, leafhoppers are also important because of aster yellows and
scorch diseases they transmit to shade trees, fruit trees, vines
and even grasses! Unfortunately, except for a few really
distinctive types of leafhoppers, most can be quite difficult to
identify to species. On most of the samples I receive, leafhoppers
are represented only by their injury (the tiny chlorotic spots)
because leafhoppers are skittish and agile. They often jump from
plant samples as the samples are cut. On trees, there is a real
hazard that leafhoppers may infest the plant with various sorts of
virus-like diseases or the xylem-inhabiting fastidious bacteria.
It is amazing that with the constant hazard of being infected by
leafhoppers that there are any live sycamores and oaks in North
Carolina, but apparently the leafhoppers are not that effective at
transmitting the diseases. Beauveria bassiana parasitic
fungus (Naturalis-O), diazinon, Dursban, neem seed extracts,
Orthene, pyrethroids and Sevin are all products labeled for
leafhopper control. However, because leafhoppers migrate readily
from place to place, it is almost impossible to get long-term
control without lots of spraying! There is additional information
on the biology of southern potato leafhoppers in AG-136, Insect
and Related Pests of Flowers and Foliage Plants, a North Carolina
Cooperative Extension Service publication that should be available
in each county Extension Center.
In North Carolina, the citrus whitefly is a pest of gardenia and
Swedish ivy. This is a relatively husky whitefly. The immature
stages of citrus whitefly are scale-like insects that suck sap from
the lower leaf surface. The eggs are so small that most people do
not even notice them. There are two or three generations of the
citrus whitefly each year. These pests suck sap from the plant and
excrete honeydew, a sweet, sticky substance. Sooty molds grow in
the honeydew and cause infested bushes to become blackened.
Orthene or Dursban should give adequate control, but horticultural
oils (Volck, Supreme, Sunspray etc.) should also give adequate
control of the citrus whitefly and should aid in causing the sooty
molds to flake away more effectively than any other pesticide.
There is additional information on the biology of citrus whiteflies
in AG-136, Insect and Related Pests of Flowers and Foliage
Plants, a North Carolina Cooperative Extension Service publication
that should be in each county Extension Center.
Orangestriped oakworms are sometimes very abundant on oaks in late
August and September. They occasionally feed on other hardwoods as
well. The moths are brown with a white spot and a dark stripe on
each forewing. The moths emerge in June and July and deposit their
eggs in clusters of several hundred eggs on the underside of oak
leaves. The eggs hatch in about a week. The tiny, greenish
caterpillars eventually grow into black caterpillars with yellow or
orange stripes running lengthwise along their bodies. These
caterpillars have a prominent pair of spines or slender horns
emerging from behind the head. Young caterpillars feed in groups,
whereas older caterpillars tend to be solitary although there may
be thousands of caterpillars on a single tree. Small trees are
sometimes completely defoliated by these pests by mid summer. Even
mature oaks may be defoliated to the point that twig dieback may
occur due to sun scald or other factors. As the caterpillars
mature, they are often seen crawling along sidewalks, driveways and
yards. These caterpillars may wander for a considerable distance
while searching for a place to pupate. They dig into the soil
three or four inches and pupate there. There is usually one
generation of orangestriped oakworms per year, and the caterpillars
overwinter as pupae in the soil. Control is complicated by the
size of many of the infested trees. Most people do not have
sprayers that can reach up very high into shade trees, and by the
time the caterpillars descend and crawl about on the soil, they are
extremely resistant to pesticides. Fortunately, late summer
defoliations are much less damaging to the health of trees than
early spring defoliations. In most cases it is probably better to
rely on birds, diseases and parasites to lower the population the
next year.
Armyworms are showing up on turf in scattered locations. If birds
are observed feeding in a turf area, this is often an indicator
that caterpillars are present. Use a soapy water flush to scout
for damaging armyworm populations. August is the time of year to
treat for white grubs. This is also the time of year that chinch
bugs begin their attack on St. Augustinegrass lawns. The dry, hot
weather we have had in many areas increases the likelihood of
damage from this pest.
Web page last updated on August 18, 1997 by Stephen J. Toth, Jr..
