Thrips (Western flower thrips and banded greenhouse thrips)
leaves become curled or distorted with silver-gray scars
or calloused areas where feeding occurred; thrips can transmit the impatiens
necrotic spot virus (INSV).
Control of thrips is difficult.
Infested rose blossoms should be removed and destroyed. Grass and weeds in the
area should be kept mowed or removed when possible. Insecticides are available
but timing of sprays is very important. They must be applied before thrips
enter unopened buds. In addition, because rose blooms expand rapidly, it is
difficult to keep them adequately covered with insecticide. If it becomes
absolutely essential to spray an insecticide, the following are available in
homeowner size packaging: acephate, bifenthrin, cyfluthrin, lambda cyhalothrin,
permethrin, or spinosad. Insecticidal soaps will help control thrips, but
thorough coverage is necessary. The soap spray must contact the pest to be
effective, and may require three sprays at 5 to 7 day intervals. Soil drenches
or granular applications of dinotefuran or imidacloprid will give thrips