> I once lost an entire garden of 23 roses to stem canker, a disease which
> causes browning, shrinkage and ultimately death of the pith in rose canes.
> The external symptom is dark purplish discolorations on the outside of the
> The roses in my new garden are beginning to show evidence of this blight.
> Please help with any advice on controlling or eradicating stem canker!
> If you see a rose with purple blotches on the stem, do not buy it! The
> disease seems to be spread by pruning, and descends down the canes until
> the heart of the plant is killed.
There is an article called "Preventing Canker, Blight, and Dieback" by
AnnHooper in the 1994 "Rose Annual" of the American Rose Society. It
offers some advice on how to reduce the incidence of fungus-caused
The loss of 23 roses is a much greater incidence of stem canker than I am
used to. In my limited experience, the disease depends on growing
conditions. In dry California, it was uncommon, and was usually confined
to a few canes. I never lost a bush to stem canker per se. In humid
Hawaii, it is more common, but still I haven't lost a bush to it alone.
More often my losses are due to some root and soil problem - waterlogging,
over-fertilizing, etc. - that slowly kills the whole bush. The article by
Hooper suggests that severe New Enland winters contribute to theproblem by
stressing the bushes and damagng the canes.
If you haven't done so already, it might be helpful seek out an expert and
get some of the diseased bushes examined by a plant pathologist. Maybe you
have something else stressing the roses.
-- Chuck Bigelow