1. Black Spots on Leaves     

This disease is commonly known as black spot. Black spots appear as circular with fringed edges on leaves. They cause the leaves to yellow. Remove the infected foliage and pick up any fallen leaves around the rose.

2. Stunted or malformed young canes

Known as powdery mildew, this is a fungal disease that covers leaves, stems and buds with wind spread white powder. It makes the leaves curl and turn purple. Spray with Funginex or Benomyl to treat this fungal disease.

3. Blistered underside of leaves

Known as rust, this disease is characterized by orange-red blisters that turn black in fall. Collect and discard leaves that are infected in fall. a Benomyl or Funginex spray every 7-10 days may help.

4. Malformed or stunted leaves and flowers

This is caused by spider mites. They are tiny yellow, red or green spiders found on the underside of leaves where they suck juices. The application of Orthene or Isotox may help in treating this infestation.

5. Weak and mottled leaves with tiny white webs under them

Often clustered under leaves and flower buds, they suck plant juices from tender buds. Malathion or diazinon spray may help roses to survive these bugs.

6. Flowers that don’t open or are deformed when they open.

Cut and discard the infested flowers. Orthene and malathion may also treat this problem.

Remember that roses are hungry feeders that require much fertilizer to become healthy bushes.