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-   -   Battle with blackspot on Roses. (https://www.gardenbanter.co.uk/gardening/150062-battle-blackspot-roses.html)

[email protected] 03-10-2006 07:49 PM

Battle with blackspot on Roses.
 
I am fairly new to Rose gardening and have one hybrid tea rose (Chihuly) right
now. I have the plant in a large plastic pot where it has been for 2 years, here in
the Dallas, TX. area. For two years I have been removing leaves that appear
infected, and spraying the top and bottoms of the leaves with the ortho
commercial fungicide (chlorothanonil). I didnt think it was helping much because
this is a constant battle, having to remove leaves, pick up the dead ones, spray,
etc... every week... I recently decided to try baking powder (I didnt have
baking soda), vegetable oil, and insecticidal soap. Mixed the appropriate levels
of each, and sprayed... Since approximately 1 week, nearly half of the leaves
appeared infected, and most have dropped off. I want to keep the rose, but I
want to try and kill this fungus somehow... ill try anything. I even thought that I
would wait until fall temps dropped and I would pull the plant out of the original
container, remove the soil completely (bare root) and cut back the topgrowth.
Bleach the container, discard the soil, and lightly spray the outside surface of the
rose plant with a 1/10 mixture of bleach or soak the plant, etc.. for a brief
period of time. What can I do? Anything?





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JoeSpareBedroom 03-10-2006 08:24 PM

Battle with blackspot on Roses.
 
"Nevermind" wrote in message
...
I am fairly new to Rose gardening and have one hybrid tea rose (Chihuly)
right
now. I have the plant in a large plastic pot where it has been for 2
years, here in
the Dallas, TX. area. For two years I have been removing leaves that
appear
infected, and spraying the top and bottoms of the leaves with the ortho
commercial fungicide (chlorothanonil). I didnt think it was helping much
because
this is a constant battle, having to remove leaves, pick up the dead ones,
spray,
etc... every week... I recently decided to try baking powder (I didnt have
baking soda), vegetable oil, and insecticidal soap. Mixed the appropriate
levels
of each, and sprayed... Since approximately 1 week, nearly half of the
leaves
appeared infected, and most have dropped off. I want to keep the rose, but
I
want to try and kill this fungus somehow... ill try anything. I even
thought that I
would wait until fall temps dropped and I would pull the plant out of the
original
container, remove the soil completely (bare root) and cut back the
topgrowth.
Bleach the container, discard the soil, and lightly spray the outside
surface of the
rose plant with a 1/10 mixture of bleach or soak the plant, etc.. for a
brief
period of time. What can I do? Anything?



1) Insecticidal soap will serve no purpose in the spray you made, and might
mess with the pH, which IIRC is the reason baking soda is sometimes
effective.

2) When you say "large plastic pot", how large, in height and width?

3) Spend some big money on a really big box of baking soda. Baking powder is
not a viable alternative.

4) Describe the placement of the pot, relative to sun, wind, other plants.



JoeSpareBedroom 04-10-2006 12:00 AM

Battle with blackspot on Roses.
 
Mixed with water and sprayed on. It then dries, leaving a bit of a film.


"Gravelle" wrote in message
...
Is the baking soda just sprinkled on the leaves, or is it mixed with
something else?

Thanks.

"JoeSpareBedroom" wrote in message
...
"Nevermind" wrote in message
...
I am fairly new to Rose gardening and have one hybrid tea rose (Chihuly)
right
now. I have the plant in a large plastic pot where it has been for 2
years, here in
the Dallas, TX. area. For two years I have been removing leaves that
appear
infected, and spraying the top and bottoms of the leaves with the ortho
commercial fungicide (chlorothanonil). I didnt think it was helping much
because
this is a constant battle, having to remove leaves, pick up the dead
ones, spray,
etc... every week... I recently decided to try baking powder (I didnt
have
baking soda), vegetable oil, and insecticidal soap. Mixed the
appropriate levels
of each, and sprayed... Since approximately 1 week, nearly half of the
leaves
appeared infected, and most have dropped off. I want to keep the rose,
but I
want to try and kill this fungus somehow... ill try anything. I even
thought that I
would wait until fall temps dropped and I would pull the plant out of
the original
container, remove the soil completely (bare root) and cut back the
topgrowth.
Bleach the container, discard the soil, and lightly spray the outside
surface of the
rose plant with a 1/10 mixture of bleach or soak the plant, etc.. for a
brief
period of time. What can I do? Anything?



1) Insecticidal soap will serve no purpose in the spray you made, and
might mess with the pH, which IIRC is the reason baking soda is sometimes
effective.

2) When you say "large plastic pot", how large, in height and width?

3) Spend some big money on a really big box of baking soda. Baking powder
is not a viable alternative.

4) Describe the placement of the pot, relative to sun, wind, other
plants.






Gravelle 04-10-2006 12:00 AM

Battle with blackspot on Roses.
 
Is the baking soda just sprinkled on the leaves, or is it mixed with
something else?

Thanks.

"JoeSpareBedroom" wrote in message
...
"Nevermind" wrote in message
...
I am fairly new to Rose gardening and have one hybrid tea rose (Chihuly)
right
now. I have the plant in a large plastic pot where it has been for 2
years, here in
the Dallas, TX. area. For two years I have been removing leaves that
appear
infected, and spraying the top and bottoms of the leaves with the ortho
commercial fungicide (chlorothanonil). I didnt think it was helping much
because
this is a constant battle, having to remove leaves, pick up the dead
ones, spray,
etc... every week... I recently decided to try baking powder (I didnt
have
baking soda), vegetable oil, and insecticidal soap. Mixed the
appropriate levels
of each, and sprayed... Since approximately 1 week, nearly half of the
leaves
appeared infected, and most have dropped off. I want to keep the rose,
but I
want to try and kill this fungus somehow... ill try anything. I even
thought that I
would wait until fall temps dropped and I would pull the plant out of the
original
container, remove the soil completely (bare root) and cut back the
topgrowth.
Bleach the container, discard the soil, and lightly spray the outside
surface of the
rose plant with a 1/10 mixture of bleach or soak the plant, etc.. for a
brief
period of time. What can I do? Anything?



1) Insecticidal soap will serve no purpose in the spray you made, and
might mess with the pH, which IIRC is the reason baking soda is sometimes
effective.

2) When you say "large plastic pot", how large, in height and width?

3) Spend some big money on a really big box of baking soda. Baking powder
is not a viable alternative.

4) Describe the placement of the pot, relative to sun, wind, other plants.




Kay Lancaster 04-10-2006 03:40 AM

Battle with blackspot on Roses.
 
I am fairly new to Rose gardening and have one hybrid tea rose (Chihuly) right

Baking powder is the wrong stuff, and a whole lot more expensive than
baking soda. A pound will set you back less than $1.

Blackspot is a fungal disease, worse during warm humid weather. The
spores are pretty ubiquitous. It tends to be worse on stressed plants,
and plants in pots are almost by definition, stressed.

Your choices are a regular program of spraying and sanitation, learning
to live with blackspot, or choosing disease resistant cultivars

American Rose Society has chapters all over:
http://www.ars.org/Districts/districts.htm, and there is also a Houston
Rose Society. A&M maintains a list of very disease resistant roses:
http://www.houstonrose.org/earthkin.htm -- you may find one there
you like better and is a whole lot easier to grow for a beginner.

Kay



Flora[_1_] 04-10-2006 10:28 AM

Battle with blackspot on Roses.
 

JoeSpareBedroom wrote:

Mixed with water and sprayed on. It then dries, leaving a bit of a film.


I usually mix baking soda 1 tsp to a litre/quart, though I suppose you could
use more
(until your sprayer nozzle blocks up).

I read about using skim milk, possibly in rec. gardens. roses, and tried it.
Apparently there's a protein in the milk that stops black spot from replicating
or sending out spores. You use skim milk because it has all the protein and
none of the fat of 2% or homo, which can
stink up your plants. It's fairly cost effective, and easy to do.

You mix 3 parts water to 1 part skim milk.

I've tried it on my roses and think it's as least as effective as baking soda,
and maybe even a bit better. It won't get rid of the black spot that's already
there, but if you spray it twice a week, and after every rain, you'll probably
see new healthy leaves growing. I also spray the ground around the plants as
there are spores in the earth as well.

Flora



Gravelle 04-10-2006 10:15 PM

Battle with blackspot on Roses.
 
Thanks, Flora. I'll give this (skim milk) a try.


"Flora" wrote in message
...

JoeSpareBedroom wrote:

Mixed with water and sprayed on. It then dries, leaving a bit of a film.


I usually mix baking soda 1 tsp to a litre/quart, though I suppose you
could
use more
(until your sprayer nozzle blocks up).

I read about using skim milk, possibly in rec. gardens. roses, and tried
it.
Apparently there's a protein in the milk that stops black spot from
replicating
or sending out spores. You use skim milk because it has all the protein
and
none of the fat of 2% or homo, which can
stink up your plants. It's fairly cost effective, and easy to do.

You mix 3 parts water to 1 part skim milk.

I've tried it on my roses and think it's as least as effective as baking
soda,
and maybe even a bit better. It won't get rid of the black spot that's
already
there, but if you spray it twice a week, and after every rain, you'll
probably
see new healthy leaves growing. I also spray the ground around the plants
as
there are spores in the earth as well.

Flora





Myrl Jeffcoat 06-10-2006 03:47 AM

Battle with blackspot on Roses.
 
You guys are on to a topic that I have been wondering about for awhile
now. I have a small rose garden in the front of my yard, which contain
7 rose bushes. All bushes appear very healthy, except for one near the
middle. Every year, it starts out ok in the Spring, but by Summer it
has developed the Black Spot that you are speaking of. No amount of
spraying, or treatment has brought it out of it. Then the following
year, it begins the cycle all over again. The first blooms of this
bush is amazing, they are absolutely abundant and beautiful, but the
bush does frustrate me.

I'm thinking of simply digging it out, and replacing it with another of
the same variety. . .Whatya think? Could this just be a weak bush,
that is more problem than it's worth?

Myrl Jeffcoat
http://www.myrljeffcoat.com


JoeSpareBedroom 06-10-2006 04:08 AM

Battle with blackspot on Roses.
 
"Myrl Jeffcoat" wrote in message
oups.com...
You guys are on to a topic that I have been wondering about for awhile
now. I have a small rose garden in the front of my yard, which contain
7 rose bushes. All bushes appear very healthy, except for one near the
middle. Every year, it starts out ok in the Spring, but by Summer it
has developed the Black Spot that you are speaking of. No amount of
spraying, or treatment has brought it out of it. Then the following
year, it begins the cycle all over again. The first blooms of this
bush is amazing, they are absolutely abundant and beautiful, but the
bush does frustrate me.

I'm thinking of simply digging it out, and replacing it with another of
the same variety. . .Whatya think? Could this just be a weak bush,
that is more problem than it's worth?

Myrl Jeffcoat
http://www.myrljeffcoat.com


Well, it could be that you've got a bush with absolutely no resistance to
disease. And, I've also read over the years that real rose fanatics plant
with a lot of space around the roses, for better air circulation. It seems
to me they'd have to be VERY crowded in order to cause problems, but maybe
not.



Myrl Jeffcoat 06-10-2006 05:41 AM

Battle with blackspot on Roses.
 
That's my take on it too Joe!. . .I think I just have a sickly bush!
The roses aren't that close together, and their is plenty of air
circulation around them, because they are out in the open, not even up
against a fence.

This January, I'm yanking that one out, giving it a proper burial, and
I'm going to replace it. . .No looking back;-)

Myrl Jeffcoat
http://www.myrljeffcoat.com


JoeSpareBedroom 06-10-2006 12:40 PM

Battle with blackspot on Roses.
 
"Myrl Jeffcoat" wrote in message
ups.com...
That's my take on it too Joe!. . .I think I just have a sickly bush!
The roses aren't that close together, and their is plenty of air
circulation around them, because they are out in the open, not even up
against a fence.

This January, I'm yanking that one out, giving it a proper burial, and
I'm going to replace it. . .No looking back;-)

Myrl Jeffcoat
http://www.myrljeffcoat.com


Every now and then, I pretend for a few minutes that bud-eating deer don't
exist in my yard, and I entertain the idea of planting some roses. At those
times, I look at one of my books which reminds me that one entire category
is pathetically weak with regard to fungal diseases, and need more chemical
support than any plant deserves, sort of like green seedless grapes. If I
recall, it's the hybrid tea roses. You should probably do some reading
before choosing your next rose. You obviously got lucky with the ones that
aren't having problems.



Kay Lancaster 07-10-2006 03:42 AM

Battle with blackspot on Roses.
 
is pathetically weak with regard to fungal diseases, and need more chemical
support than any plant deserves, sort of like green seedless grapes. If I
recall, it's the hybrid tea roses. You should probably do some reading


They'll also do well with decent soil, a little fertilizer and water
and some benign neglect, if well chosen.

Quite a few current breeding programs stress developing disease resistant,
resilient cultivars.

JoeSpareBedroom 07-10-2006 04:11 AM

Battle with blackspot on Roses.
 
"Kay Lancaster" wrote in message
...
is pathetically weak with regard to fungal diseases, and need more
chemical
support than any plant deserves, sort of like green seedless grapes. If I
recall, it's the hybrid tea roses. You should probably do some reading


They'll also do well with decent soil, a little fertilizer and water
and some benign neglect, if well chosen.


True. In my previous house, I had "beach roses" - rugosa, I suppose. Utterly
bulletproof. No diseases, they laughed at chunks of ice that fell from the
roof, and they bloomed from spring until heavy frost. They were single
flowers, which don't make rose worshippers' hearts flutter, but they scented
the whole yard.



Ann 07-10-2006 12:04 PM

Battle with blackspot on Roses.
 
"JoeSpareBedroom" expounded:


True. In my previous house, I had "beach roses" - rugosa, I suppose. Utterly
bulletproof. No diseases, they laughed at chunks of ice that fell from the
roof, and they bloomed from spring until heavy frost. They were single
flowers, which don't make rose worshippers' hearts flutter, but they scented
the whole yard.


I love them for that very reason - their perfume.

To me, no matter how beautiful a multipetaled rose is, if it has no
scent, it's just not going to grow in my garden.
--
Ann, gardening in Zone 6a
South of Boston, Massachusetts
e-mail address is not checked
******************************

[email protected] 07-10-2006 02:56 PM

Battle with blackspot on Roses.
 
when I was in my "rose" phase I became aware of how important early morning sun and
good ventilation is to drying off the bush. and needless to say, no watering after
morning that would get the leaves wet. Ingrid


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