PLEASE, PLEASE help with stem canker!

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PLEASE, PLEASE help with stem canker!

Post by Wendy B » Sun, 23 Feb 1997 04:00:00



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
canes.

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.

 
 
 

PLEASE, PLEASE help with stem canker!

Post by Wynand Har » Mon, 24 Feb 1997 04:00:00


Wendy, This is caused by a parasitic fungus entering the stem through a
wound.  Brown and rough with swollen edges, stem canker resembles an
infected wound, and when it has encircled the stem the stem will die.
Control - Cut off the affected stem as soon as canker is noticed, and
disinfect the secateurs in a bucket containing one part formalin and 5
parts water.  As hailstorms frequently cause damage to young stems, it is
sensible to inspect all rose plants after a storm, cutting off those stems
that have been badly battered and spraying others that are less bruised
with Dithane M45 at four times the usual strength.  In caring for roses,
prevention is always better than cure, so it is sensible to spray every two
weeks from the end of Sept (SA) using the relevant chemicals.  Removing
dense lower growth regularly from your roses will improve air circulation
around the plants and inhibit the spread of certain diseases, it will aslo
make the application of all remedies more feective.  Petro  
--
Petro And Wynand Hart
Pietermaritzburg
South Africa



Quote:
> 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
> canes.

> 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.

 
 
 

PLEASE, PLEASE help with stem canker!

Post by sub ros » Mon, 24 Feb 1997 04:00:00


There are a number of cankers (see "Compendium of Rose Diseases") and
some can be controlled and some can't. I suggest you call your local
extension agent and/or Consulting Rosarian. Your roses need to be looked
at. Meanwhile, cut below the discoloration and spray any cuts with a
fungicide.Cankers are a fungus and can be spread by
contact/air/water,etc. You really need to find out which one you have.

 
 
 

PLEASE, PLEASE help with stem canker!

Post by Charles Bigel » Mon, 24 Feb 1997 04:00:00




Quote:
> 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
> canes.

> 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
diebacks.

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