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Plant Diseases/diseased rose stems


a shrub rose, "cariad" in it's second year has signs of diseased stems.
can you suggest treatment or even a plant rescue?
there are blackish reddish speckles all over, with one brown all over,
and another looks dead- yellowish.

thankyou melissa and god day


Dear Philip, It sounds like you have canker on your rose stems.  It is a pesky disease, but you should be able to cure it.  You need to prepare a solution of 1 part bleach to 10 parts water, and get clean pruning shears.  And often I hear this advice on keeping the shears sterilized between cuts and I rarely go to that much trouble, although this is one time when you really should.  You need to cut off each affected stem well below the diseased part, and place each diseased stem in the trash and remove it from your garden.  DO NOT compost any of the stems.  Cut each affected stem cleanly and then dip the pruners in the bleach solution.  This should help the new stems come out disease free.  However, you also mention speckles and I wonder if you also may have spider mites.  This would be a reasonable assumption since you already have a plant that is sickly and bugs will attack plants more often if there is already something wrong with it.  To test for spider mites, take a few leaves, hold them over a white sheet of paper and rap them sharply over the paper.  You may see something falling on the paper.  If any specks move, then you have spider mites.  (Interestingly, and completely beside the point, if you draw a circle around the spider mite with an ink pen, the mite will wander around the circle and be unable to cross the line for a while.  If you make a circle with an opening, then the mite will walk around until it finds the opening and leave that way.)  If you do have spider mites, you can spray the plants with NEEM or another product specific for killing spider mites.  Other than that, dispose of the diseased stems and be vigilant about looking for new cankers on stems, and your roses should be in fine shape very soon.  I hope this information helps you, but please write back if you have more questions.  Good luck, Melissa

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Melissa Johnston


Plant diseases, landscaping, tropical plants, roses, herbs, plant care, grafting, horticulture, plant identification, anything about plants I can likely answer.


35 years experience in various plant businesses, 1984 Certified Texas Master Gardener.

Master Gardener Association of Texas charter member

none as of yet, but I have a plant q&a book I am in process of submitting.

Magna cum laude graduate of Texas A&M, 1978

Awards and Honors
Plant growing awards, highest grade for Texas Master Gardener graduates.

Past/Present Clients
Past member of and was very highly rated. Owned landscape company in the past, Almost Paradise, and was very successful despite little equipment, no help, and no advertising. Lived well for two years until 9/11.

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