Roses are flowering perennial plants prized for their beautiful flowers, which are made up of delicate and layered petals. One of the best ways to propagate new roses is to take a cutting from an existing plant and grow it into a whole new rose bush. When you grow roses from a cutting, you cut a stem from a healthy plant and root it in a growing medium so it grows into an independent plant of its own. However, you can also propagate roses by dividing an existing plant, but this requires a little more effort than with cuttings. To propagate by division, you have to dig up an entire rose bush, cut the root system in half, and replant the two halves as separate bushes.
This is a fungus called black spot. Left untreated, it can cause all the leaves on your roses to turn yellow and fall off. It will also affect nearby plants, as it spreads by spores. Remove ALL INFECTED material and throw it away or burn it. Do NOT leave it on the ground as this fungus is very hardy. It can survive winter and travels very easily, even after being removed from the affected plant. Spray your plants regularly (bi-weekly) in the growing season with a good fungicide (I like the Bayer products). You can also add a little bit of dish soap and baking soda to a spray bottle with water and spray the entire plant.
Cover the cutting loosely, pot and all, with a plastic bag or plastic wrap and keep the soil moist. Putting a tall stake into the pot will hold the plastic away from the leaves. If the plastic touches the leaves, they remain wet and can succumb to a fungus disease. Along the same lines, make sure the condensation can escape from the plastic or the stem will rot.