Spray with an insecticidd and make sure the insecticide covers the undersides of leaves. Buds do not open, or flowers are deformed. Petals have brownish yellow streaks and small dark spots or bumps. White and pastel roses are particularly susceptible. Thrips, tiny orange insects with elongated bodies.
Thrips feed at the bases of rosebuds and on the petals of open flowers.
They seem to be attracted to light-colored blossoms. To discourage thrips from attacking, spray plants with a systemic insecticide just before the buds open. If signs of thrip damage appear, remove and destroy infected flowers and buds. Spray infected plants with an insecticide. If the infestation is severe, repeat applications may be necessary.