A couple of my rose bushes have thick stems shooting up between the green stems. They have buds on them that appear to be smaller in size compared to the green stems. Each of the plants have 3 or 4 of the thicker, almost deep red in color. These stems tower above the green stems by nearly double in height.
They are suckers. Cut them all the way down to the main part of the bush. They make the plant weaker by taking more water from the main plant.