Your plant has a bad infestation of scale insects. The cure is simple enough but actually doing it on the hedge will be challenging. What you do is spray the ENTIRE plant, ALL of the stems and leaves, completely covering the entire plant with the spray. The spray is Neem Oil. Get a fresh bottle because this stuff has a fairly short shelf life. Mix per directions and spray the plant every 7-9 days. You should do this at least 3 times. Some of the scale on your plant is called hard scale or armored scale. This insect has permanently attached itself to the plant and has grown and covered itself with a hard coating, sort of like a barnacle. The way these things are killed is by smothering them and the oil in the Neem Oil does this very effectively. Once the scale is dead it will NOT fall off of the plant. It will stay there until the plant grows enough to force it off. Your plant has both hard and soft scale, the soft scale being the young immature offspring of the hard scale. These scale are mobile and much easier to kill than the hard scale. The insecticide in the Neem Oil is what kills these insects. The reason you should spray at least 3 times is to make sure that you have killed all of the scale AND their eggs. Scale can and will kill a plant if it is not eliminated. Just remember that you MUST cover every inch of the plant with the neem.
