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Blackspot on roses near tree

Does being near or under a tree make blackspot worse? My Kentucky Derby is
always COVERED with blackspot, and no amount of anything will keep it from
looking pitiful. The tree is a crabapple, I think. I have 3 other roses
under the same tree (it doesn't block their sun) and they all have minor
blackspot too, though not as much. I wonder if the tree makes it worse? Or
weeds? Does anyone else have a blackspot problem with Kentucky Derby?

JimS.
Seattle

Blackspot on roses near tree

"JimS." wrote in message
news:kPPBa.1038545$3D1.607580@sccrnsc01...
Does being near or under a tree make blackspot worse? My Kentucky Derby
is
always COVERED with blackspot, and no amount of anything will keep it from
looking pitiful.

The sun helps to keep the leaves dry, and direct sunlight helps to keep the
spores from germinating, so its position in partial shade may have more to
do with it than the variety. I don't have that variety, but I have noticed
that the roses in *full* sun have noticeably less fungal disease in general,
than those who share their sunlight.

Scopata Fuori

Blackspot on roses near tree

On Fri, 30 May 2003 21:12:48 GMT, "JimS."
wrote:

Does being near or under a tree make blackspot worse? My Kentucky Derby is
always COVERED with blackspot, and no amount of anything will keep it from
looking pitiful. The tree is a crabapple, I think.

I believe I read somewhere that roses and some fruit trees share the
same propensity for fungal diseases.

Anyone hear of that?

Blackspot on roses near tree

Shiva wrote:

I believe I read somewhere that roses and some fruit trees share the
same propensity for fungal diseases.

Anyone hear of that?

I've seen some of the same diseases listed, that affect my roses, listed on
my fruit tree sprays. But perhaps I have been lucky, or maybe my roses are
just much more tasty than my peach or apples, as I have never seen a trace
of BS on those. I do get a horrific blight on the peaches, though, that I
have yet to conquer, that turns them all into rotten, fly swarmed messes.
I'm hoping this year's spray of Messenger and bt will keep it in check. If
not, I plan to take a sample into the local county agricultural extension
office, for further identification and advice on how to thwart it.

Scopata Fuori

Blackspot on roses near tree

"JimS." wrote

Does being near or under a tree make blackspot worse? My Kentucky Derby
is
always COVERED with blackspot, and no amount of anything will keep it from
looking pitiful. The tree is a crabapple, I think. I have 3 other roses
under the same tree (it doesn't block their sun) and they all have minor
blackspot too, though not as much. I wonder if the tree makes it worse?
Or
weeds? Does anyone else have a blackspot problem with Kentucky Derby?

JimS.

Hello Jim,

Are you sure it is blackspot and not cercospora?
The trees in the park around us have a constant strain of cercospora and
naturally everything including our roses are spotted with it. Actually the
two roses under our crabapple Brandywine are clean as whistles. Check this
link for the cercospora info.

http://www.aces.edu/department/extco...5/anr-505.html

Allegra

Blackspot on roses near tree

Hi Allegra,
Nope, it's not cercospora. It's definitely blackspot. I think it's just a
problem with that Kentucky Derby. The spotting on the other roses is minor
and probably just because I'm not aggressive enough on the fungicides. But
the K.D. is almost a lost cause, spotwise. If the spot wasn't so crowded
I'd dig it up and plant something else. But considering how crummy a spot
it is, I guess I will just live with the spots. At least the blooms are
nice.

JimS.

"Allegra" wrote in message
et...

"JimS." wrote

Does being near or under a tree make blackspot worse? My Kentucky Derby
is
always COVERED with blackspot, and no amount of anything will keep it
from
looking pitiful. The tree is a crabapple, I think. I have 3 other roses
under the same tree (it doesn't block their sun) and they all have minor
blackspot too, though not as much. I wonder if the tree makes it worse?
Or
weeds? Does anyone else have a blackspot problem with Kentucky Derby?

JimS.

Hello Jim,

Are you sure it is blackspot and not cercospora?
The trees in the park around us have a constant strain of cercospora and
naturally everything including our roses are spotted with it. Actually the
two roses under our crabapple Brandywine are clean as whistles. Check this
link for the cercospora info.

http://www.aces.edu/department/extco...5/anr-505.html

Allegra

Blackspot on roses near tree

As has been mentioned, good horticultural practices and selelection of
resistant varieites are the best method to minimize black spot and the other
fungal diseases.

Note that the scientific name of most of the fungal diseases include the
word 'rosa' in some form. These diseases are specific to roses and are not
transmitted from non-rose plants or trees.

Education and prevention are the operative words, good garden sanitation,
selection of resistant varities and if necessary a regular preventative
spray program will keep your roses healthy and disease free.

I have 'shovel pruned' a number of varities over the years,
the 'disease magnets' are just not worth keeping.

Just my $0.02 worth,

Tim

Blackspot on roses near tree

After Tim Tompkins got finished preaching to us about proper selection
techniques that would rule out most if not all of the roses I want to
grow here in the swamps, he said:

Note that the scientific name of most of the fungal diseases include the
word 'rosa' in some form. These diseases are specific to roses and are not
transmitted from non-rose plants or trees.

This is hairsplitting of the highest degree. The same mold or other
fungus spores that cause downy mildew on peach trees causes downy
mildew on rose plants. Once on the rose plant, it gets the "rosae"
tag, Latin for "of rose" simply because in that particular case it is
ON A ROSE PLANT.

As for black spot, the fungus Diplocarpon rosae causes black spot in
roses.

The fungus Diplocarpon earliana causes a similar disease in
strawberries. Here is a site that discusses it:

http://www.inra.fr/Internet/Produits...ne/6dipear.htm

Diplocarpon mespili causes leaf spots in hawthorne trees that result
in defoliation. While the disease is referred to as Hawthorn Leaf
Blight, its action is the same as that of diplocaron in roses. Here is
the Cornell site that discusses this:

http://plantclinic.cornell.edu/FactS.../hawblight.htm

Therefore, while one may certainly say that apple trees do not get
black spot, one may not say that the fungus causing the disease is
specific to ROSES.

Here is one link that demonstrates that apple and peach trees are
subject to thesome of the same fungal diseases as roses.

http://www.ca.uky.edu/agcollege/plan...n/homefung.htm

Here is another that describes fungal diseases roses and fruit trees
sha

http://pearl.agcomm.okstate.edu/plan...ses/f-7617.pdf

This site discusses anthracnose in trees--we already know it occurs in
roses:

http://pearl.agcomm.okstate.edu/plan...ses/f-7634.pdf

Although certainly not a fruit tree, Dogwoods are quite common around
here and are prone to Cercospora leaf spot, just as roses are.

This UC Davis site discusses the fungus Sphaerotheca pannosa, which
causes powdery mildew, and notes that rosae is one variety of the
disease caused by this fungus--the one on roses.

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7463.html

What I was remembering was reading that roses and some fruit trees
share a propensity for fungal disease--not necessarily black spot,
just fungus in general.

Apple and Pear trees are susceptible to scab, which is a disease
caused by the fungus venturia inaequalis. If you look at the photos
on this page:

http://www.caf.wvu.edu/kearneysville/wvufarm11.html

you will see that apple, cherry, and peach trees suffer from a variety
of leaf spot diseases that cause defoliation. While these specific
diseases may not travel from the fruit trees to roses, the conditions
which would foster fungal disease in fruit trees would also do so in
roses.

All of the above may be avoided by the regular application of
appropriate fungicides. If one is willing to do this, one may grow any
rose that strikes one's fancy. I do this and I highly recommend it.

Blackspot on roses near tree

"Shiva" wrote in message
s.com...

This is hairsplitting of the highest degree. The same mold or other
fungus spores that cause downy mildew on peach trees causes downy
mildew on rose plants. Once on the rose plant, it gets the "rosae"
tag, Latin for "of rose" simply because in that particular case it is
ON A ROSE PLANT.

Excellent points. It could well be, that whatever was bothering my roses,
was what was eating my fruit trees, although the symptoms may not have been
identical. Same disease, different effects. I'm hoping that Messenger gives
my fruit trees enough resistance this year to ward off the rotting blight
that ruins every last peach. My neighbor came over this afternoon, and
commented on how noticeably free of blackspot my roses are, and was
impressed by the significant difference in my group of seven Messenger
treated mini in pots, vs. the seven controls.

I hope this is not a "diminishing returns" sort of thing, where the effects
will lessen over time. I don't expect this product to be a "magic bullet,"
but if it gives my plants enough of a boost so they can fight more of their
own battles, that's less chemical warfare I have to wage. I use a modified
IPM program, but have had to resort to the Weapons of Fungal Destruction
when the determination of the local fungus population overwhelms the care I
have taken to provide a fungus-unfriendly habitat. The botrytis outbreak was
quickly curbed by the prompt application of the Banner Maxx mixture I
sprayed last week. And I hope keeping the rose gardens airy and uncrowded
discourages its return anytime soon.

Scopata Fuori

"Bad cat!"

Blackspot on roses near tree

lms wrote:

R. foetida, full sun 24 hours a day;

Where are you that you get 24 hours of sun?

--
Henry

Blackspot on roses near tree

Where are you that you get 24 hours of sun?
must be up north.... way up north...
:)

--
be safe.
flip
^___^ Count to three. Make a wish. Close your eyes.
\^.^/ Wait. Scratch that, reverse it.
==u== - apologies to Roald Dahl

Blackspot on roses near tree

On Mon, 2 Jun 2003 11:57:50 -0400, Philip Edward Lewis
wrote:

Where are you that you get 24 hours of sun?
must be up north.... way up north...
:)

He's from Outer blinking Space.

The sun is on the other side of his eyes. Set Number 2.

Blackspot on roses near tree

On Sun, 1 Jun 2003 18:00:11 -0400, "Scopata Fuori"
wrote:

Excellent points. It could well be, that whatever was bothering my roses,
was what was eating my fruit trees, although the symptoms may not have been
identical. Same disease, different effects. I'm hoping that Messenger gives
my fruit trees enough resistance this year to ward off the rotting blight
that ruins every last peach.

So that is what Messenger is for. I'll have to look into it.