ORNAMENTALSAND
TURF
ORNAMENTALS
The information and recommendations in this newsletter are applicable to North Carolina
and may not apply in other areas.
The flower thrips is an common and sometimes very damaging pest of
roses and other ornamental plants, especially those plants with
white or pale blooms. Flower thrips breed on grasses, weeds,
field, forage and truck crops, fruit trees, shade trees, brambles
and vines. They prefer grasses, legumes, roses and peonies. As
the winter grains mature and the winter annual weeds die, a
tremendous number of flower thrips will start flying in search of
new host plants. When their host plant becomes unsuitable or the
thrips become crowded, flower thrips start flying whenever light
intensity reaches 100 foot candles and the temperature reaches 63
to 68 degrees F. In North Carolina, there is a major thrips flight
in late May and early June and another noticeable flight in late
August and early September. Because of the tremendous feral
population of flower thrips which is never sprayed, the flower
thrips is among the most pesticide-susceptible thrips. However,
during the spring and summer flights, they appear to be resistant
because of the number of new thrips which begin arriving as soon as
the pesticide residue dries. Almost half of the complaints
concerning flower thrips received by the Plant Disease and Insect
Clinic at North Carolina State University are from people bitten by
the thrips. Migrating thrips probe new plants as they land and
apparently probe humans as well. Ornamentals and Turf Insect Note
No. 21 gives additional information on the biology and control of
flower thrips.
Pine bark adelgids are tiny, aphid-like insects that secrete a
fluffy, white material on the bark of white pines. They are the
most commonly reported pest of white pine and are often confused
with woolly aphids, mealybugs or fungi. Pine bark adelgids usually
do not cause dieback unless their populations are very dense. They
seem to do the most harm to small trees. Heavily infested trees
may turn yellow and be stunted. White pines in many parts of North
Carolina should almost be considered bedding plants. They are not
adapted to areas other than the mountains and a few native stands
in Chatham and Durham Counties, North Carolina. However, even in
the Coastal Plains of North Carolina an occasional white pine may
survive for decades (perhaps, 1 of 100 trees). There is no problem
with planting seed-grown white pines in the Piedmont and Coastal
Plains as long as people realize some of the trees may die each
year. At least they get some enjoyment from the trees for 5 to 7
years. Adelgids are susceptible to insecticidal soaps and
horticultural oils. Ornamentals and Turf Insect Note
No. 62
gives more information on the biology and control of pine bark
adelgids. A copy should be located in each county extension center
in North Carolina.
Boxwood psyllids are small, leafhopper-like insects that overwinter
as nymphs in the buds of boxwoods. In the spring, the nymphs feed
in new growth causing it to become cupped and distorted. The
cupped leaves form a shelter in which the nymphs feed and secrete
their fluffy white wax. Adults emerge in May and June. Eggs are
laid in early summer and hatch in late summer, but the new psyllid
nymphs stay buried in the buds until the following spring. The
best time to treat for boxwood psyllids nymphs is in April. Adults
can be treated in May and June. Ornamentals and Turf Insect Note
No. 53, the Boxwood Pest Control Calendar, provides information
on the best time to treat for the various pests of boxwood and
which pesticides are available. A copy should be located in each
county extension center in North Carolina.
Web page last updated on 3 June 1996 by Stephen J. Toth, Jr..
