Poor flowers on Knockout rose bushes - Knowledgebase Question

Lancaster, Ma
Avatar for themacleodfa
Question by themacleodfa
June 30, 2010
I have four single Knockout rose bushes that have been excellent and trouble free for years. This year most of the flowers are only about an inch across, pink and whitish and mis-shaped.Some buds don't open at all.The bushes look healthy. Could it be Thrips or do you think it is a disease? Thanks, Bruce

Answer from NGA
June 30, 2010
It sounds like it could indeed be thrips. Feeding by these tiny insects causes flower buds to be deformed and often fail to open. Open blossoms, especially light colored ones, may have brown streaks or spots. Unfortunately, they are hard insects to control because they are safe from pesticides when they are inside the buds. Remove and destroy infested buds and flowers as soon as you notice them, keep down weeds in the area as thrips breed in them, and spray with insecticidal soap, spinosad or neem oil.

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