Question
I know that rust occurs on roses since I had that problem two blooms ago. This last fall, one of my rhodies and several arronsbeard st johns wort turned rust in color. Rhodies on either side were not affected. Is this a bacteria or parasite and can you recommend a solution. Thanks

Answer
Dorene,

There are two seperate things that I could attribute the rust color to- Mites or Phythophora canker. I would lean more towards Mites.

To treat mites, use a registered miticide on the undersides of the leaves. This should be done at least twice. Ferilize the plant and keep it well watered.

For Phythora, you will need to treat the plants with a registered fungicide that is labeled for the disease.

Good luck,
Ed Gulliksen