Question
I have a orchid plant that has developed small brown round growths under the leaves.The plant seens to be healthy and has just finished flowering.Should I be concerned. It also has new groth on it.

Answer
My best guess is that you have a brown scale infestation. To test this hypothesis, take a Q-tip and soak it in rubbing alcohol and rub one of these "growths".  If it readily comes off. it is likely a scale insect. Each scale insect is less than a 1/4" in diameter but they multiply rapidly and can form colonies.

If it is scale, you should be concerned. They are sucking insects, multiply rapidly, and eventually will crawl to all parts of the plant and kill it. If the adult form of the scale is limited to certain parts of the plant, you can clean those parts of the plant with cotton or cloth soaked in alcohol to be rubbed on the affected areas. The part you are observing is the adult phase and called a "sacle' due to appearance. There also is a "crawler" phase in its life cycle (before it forms the scale) which blends in more  with the plant tissue and moves from one part of the plant to another.  So, you could remove all of the visible scale under the leaves and still have crawlers and eggs.  You will need to continue to watch for continued infestation.  As a preventative, you could use a systemic insecticide which gets into the plant tissues and kills the insects as they suck the plant juices.  Check with your local garden center for the type of systemic insecticide they have available.