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Natty Dread
Guest
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 Posted: Mon May 29, 2006 2:24 am Post subject: Treating powdery mildew in potted rose |
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[cross-posted to rec.gardens]
Hi all - I recently potted a new John F. Kennedy rose that is about 3.5 feet
tall and has multiple canes with a few buds which are about to open. A lot
of the leaves, especially at the top of the canes, are curling at the edges
and have a white cast to them, which from my online research looks just like
powdery mildew. What would be the best way to treat that in a potted rose?
Should I remove all the infected leaves and cut back the canes, or try to
treat it with fungicide first? It would be a shame to cut it back
severely -- the bush has a nice upright shape and strong, healthy canes.
Also, I read that neem oil shouldn't be applied when temps are over 90
degrees; does that mean it shouldn't be used in hot weather at all, or just
not actually applied to the leaves when the temp is above 90? Thanks in
advance for any assistance.
Rhonda
Richmond, VA
USDA Zone 7
*********
Basic human psychology is one of my subroutines. |
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Gail Futoran
Guest
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| Posted: Mon May 29, 2006 9:04 am Post subject: Re: Treating powdery mildew in potted rose |
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"Natty Dread" <rthissenYO@ADRIANcomcast.net> wrote in message
news:Q5qeg.10474$c92.3932@fe09.news.easynews.com...
| Quote: | [cross-posted to rec.gardens]
Hi all - I recently potted a new John F. Kennedy rose that is about 3.5
feet
tall and has multiple canes with a few buds which are about to open. A lot
of the leaves, especially at the top of the canes, are curling at the
edges
and have a white cast to them, which from my online research looks just
like
powdery mildew. What would be the best way to treat that in a potted
rose?
Should I remove all the infected leaves and cut back the canes, or try to
treat it with fungicide first? It would be a shame to cut it back
severely -- the bush has a nice upright shape and strong, healthy canes.
Also, I read that neem oil shouldn't be applied when temps are over 90
degrees; does that mean it shouldn't be used in hot weather at all, or
just
not actually applied to the leaves when the temp is above 90? Thanks in
advance for any assistance.
Rhonda
Richmond, VA
USDA Zone 7
|
I have one rose that occasionally gets powdery
mildew and I tend to use the organic
solution - baking soda. Check out the article
at the American Rose Society for a variety
of solutions:
http://www.ars.org/About_Roses/disease_powdery1.htm
I can't comment on the use of neem oil
over 90 degrees, first because I've never
used neem oil, second because it's hard to
find daily temps *below* 90 degrees around
here during the growing season!
Gail
near San Antonio TX Zone 8 |
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Natty Dread
Guest
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| Posted: Mon May 29, 2006 6:06 pm Post subject: Re: Treating powdery mildew in potted rose |
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"Gail Futoran" <futoran@nospam.worldnet.att.net> wrote in message
news:Nhveg.182227$eR6.17033@bgtnsc04-news.ops.worldnet.att.net...
| Quote: | "Natty Dread" <rthissenYO@ADRIANcomcast.net> wrote in message
news:Q5qeg.10474$c92.3932@fe09.news.easynews.com...
[cross-posted to rec.gardens]
Hi all - I recently potted a new John F. Kennedy rose that is about 3.5
feet
tall and has multiple canes with a few buds which are about to open. A
lot
of the leaves, especially at the top of the canes, are curling at the
edges
and have a white cast to them, which from my online research looks just
like
powdery mildew. What would be the best way to treat that in a potted
rose?
Should I remove all the infected leaves and cut back the canes, or try to
treat it with fungicide first? It would be a shame to cut it back
severely -- the bush has a nice upright shape and strong, healthy canes.
Also, I read that neem oil shouldn't be applied when temps are over 90
degrees; does that mean it shouldn't be used in hot weather at all, or
just
not actually applied to the leaves when the temp is above 90? Thanks in
advance for any assistance.
Rhonda
Richmond, VA
USDA Zone 7
I have one rose that occasionally gets powdery
mildew and I tend to use the organic
solution - baking soda. Check out the article
at the American Rose Society for a variety
of solutions:
http://www.ars.org/About_Roses/disease_powdery1.htm
I can't comment on the use of neem oil
over 90 degrees, first because I've never
used neem oil, second because it's hard to
find daily temps *below* 90 degrees around
here during the growing season!
Gail
near San Antonio TX Zone 8
|
Am I correct in assuming you make a baking soda solution in water? If so,
what concentration are you using and are you spraying it directly on the
leaves? Thanks so much for responding - I love this bush and I don't want
to lose it the first year!
Rhonda
> |
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jtill
Guest
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| Posted: Mon May 29, 2006 6:22 pm Post subject: Re: Treating powdery mildew in potted rose |
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Gail
Will this raise the pH in the pot above what the plant needs? Tha
baking soda.Do I need to do something to avoid that?
Joe T
Baytown
PS; The link you posted gave me the full story on PM for the first
time. Thanks. |
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Gail Futoran
Guest
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| Posted: Mon May 29, 2006 8:20 pm Post subject: Re: Treating powdery mildew in potted rose |
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"jtill" <jtill10610@aol.com> wrote in message
news:1148912545.735567.158210@g10g2000cwb.googlegroups.com...
| Quote: | Gail
Will this raise the pH in the pot above what the plant needs? Tha
baking soda.Do I need to do something to avoid that?
Joe T
Baytown
PS; The link you posted gave me the full story on PM for the first
time. Thanks.
|
Hi Joe -
The nice thing about potted plants is that the
water and excess minerals run out the bottom.
I'd be more concerned about an excess of
baking soda used on plants in the ground.
There are some great sites out there for
information. Several states and university
ag departments also have good information.
My bookmark file looks like the Library of
Congress! LOL
Gail
near San Antonio TX Zone 8 |
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Gail Futoran
Guest
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| Posted: Mon May 29, 2006 8:20 pm Post subject: Re: Treating powdery mildew in potted rose |
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"Natty Dread" <rthissenYO@ADRIANcomcast.net> wrote in message
news:_dDeg.133922$bL2.79987@fe02.news.easynews.com...
| Quote: |
"Gail Futoran" <futoran@nospam.worldnet.att.net> wrote in message
news:Nhveg.182227$eR6.17033@bgtnsc04-news.ops.worldnet.att.net...
"Natty Dread" <rthissenYO@ADRIANcomcast.net> wrote in message
news:Q5qeg.10474$c92.3932@fe09.news.easynews.com...
[cross-posted to rec.gardens]
Hi all - I recently potted a new John F. Kennedy rose that is about 3.5
feet
tall and has multiple canes with a few buds which are about to open. A
lot
of the leaves, especially at the top of the canes, are curling at the
edges
and have a white cast to them, which from my online research looks just
like
powdery mildew. What would be the best way to treat that in a potted
rose?
Should I remove all the infected leaves and cut back the canes, or try
to
treat it with fungicide first? It would be a shame to cut it back
severely -- the bush has a nice upright shape and strong, healthy canes.
Also, I read that neem oil shouldn't be applied when temps are over 90
degrees; does that mean it shouldn't be used in hot weather at all, or
just
not actually applied to the leaves when the temp is above 90? Thanks in
advance for any assistance.
Rhonda
Richmond, VA
USDA Zone 7
I have one rose that occasionally gets powdery
mildew and I tend to use the organic
solution - baking soda. Check out the article
at the American Rose Society for a variety
of solutions:
http://www.ars.org/About_Roses/disease_powdery1.htm
I can't comment on the use of neem oil
over 90 degrees, first because I've never
used neem oil, second because it's hard to
find daily temps *below* 90 degrees around
here during the growing season!
Gail
near San Antonio TX Zone 8
Am I correct in assuming you make a baking soda solution in water? If so,
what concentration are you using and are you spraying it directly on the
leaves? Thanks so much for responding - I love this bush and I don't want
to lose it the first year!
Rhonda
I honestly can't remember what I did but the |
instructions at the ars site seem pretty specific:
"Controlled experiments were conducted for some three years, using sodium
bicarbonate or potassium bicarbonate in various combinations with
insecticidal soap, SunsprayŽ ultra-fine spray oil, or only water. The
result: both diseases were subdued by a weekly spraying of either sodium or
potassium bicarbonate at 3 teaspoons per gallon of water, combined with
Sunspray at 2 tablespoons per gallon of water. The bicarbonates eliminated
the fungi, but addition of the Sunspray provided a spreader-sticker action
that increased its performance."
I've never used Sunspray. For sticking I tend
to use Ivory liquid soap. Yep, the solution is
to spray on the leaves. Moderation is the key.
I hear what you're saying about loving the
bush - I have a number of roses like that - but
the John F Kennedy rose shouldn't be that
hard to replace it. It's one of the hardest
lessons I had to learn! Even now I have
favorites that won't thrive in the ground, so I
coddle them in pots. :)
Gail
near San Antonio TX Zone 8 |
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elsie
Guest
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| Posted: Tue May 30, 2006 10:23 am Post subject: Re: Treating powdery mildew in potted rose |
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Hi Rhonda, to stop the powdery mildew from spreading you should remove
the infected leaves and cut back the stems, (not too severely - only
just past where the mildew grows down to - which shouldn't be too
far).....I know it's heartbreaking to do, but it does repeat flower,
so you will still get your flowers -just a little later than you'd have
prefered! and I'm sure you'd rather get rid of the spores now, to
prevent any more spread of the disease. Also throw the diseased
material in the garbage or burn it. The carb soda recipe should do the
trick, I'll give you the recipe i have used with success at the rose
garden i tend that has over 60 roses growing in it. 3 tspns bicarb, 1
and 1/2 tbspns vegetable oil and 1/2 tspn dishwashing liquid (the
dishwashing liquid helps disperse the oil into the water) mix this with
1 gallon of water. and spray every 7 - 10 days on all the leaves and
stems of the rose. Don't spray this during the hottest part of the day,
and make sure you give the plant a good watering the day before you
spray.(esp seeing it's in a pot) You may have to keep this up for 4-6
weeks or longer until the ideal environment for mildew to develop (ie
warm days/cool nights/humidity) passes and the new spring growth
"toughens up" and is not so susceptible. Also, next year, get in
earlier with this spray, maybe early spring, to prevent it from
re-occuring. Good luck with it, Elsie
This is for Joe, the amount of bicarb being sprayed every 7-10 days
isn't anywhere near enough to change the ph of the soil. Cheers |
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jtill
Guest
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| Posted: Tue May 30, 2006 6:44 pm Post subject: Re: Treating powdery mildew in potted rose |
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Thanks Elsie
Joe T |
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Gail Futoran
Guest
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| Posted: Tue May 30, 2006 10:02 pm Post subject: Re: Treating powdery mildew in potted rose |
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"jtill" <jtill10610@aol.com> wrote in message
news:1149000275.750843.47960@j73g2000cwa.googlegroups.com...
| Quote: | Thanks Elsie
Joe T
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Agreed, that was a good post - well worth
saving! Thanks to Elsie.
Gail
near San Antonio TX Zone 8 |
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jtill
Guest
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| Posted: Tue May 30, 2006 11:15 pm Post subject: Re: Treating powdery mildew in potted rose |
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Hey all, dropped by LOWE's , "YEAR AROUND DORMANT OIL" 11.98 per quart.
I checked contents. CANOLA OIL 98%, Inerts 2%. WOW!
CANOLA is $2.50 qt. at Kroger.
Joe T |
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Gail Futoran
Guest
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| Posted: Wed May 31, 2006 2:31 am Post subject: Re: Treating powdery mildew in potted rose |
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"jtill" <jtill10610@aol.com> wrote in message
news:1149016527.741058.231800@i40g2000cwc.googlegroups.com...
| Quote: | Hey all, dropped by LOWE's , "YEAR AROUND DORMANT OIL" 11.98 per quart.
I checked contents. CANOLA OIL 98%, Inerts 2%. WOW!
CANOLA is $2.50 qt. at Kroger.
Joe T
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LOL! And with the grocery store canola oil
you can fry up and eat the rose blooms after
you treat the leaves. :)
Gail
near San Antonio TX Zone 8 |
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elsie
Guest
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| Posted: Wed May 31, 2006 2:34 pm Post subject: Re: Treating powdery mildew in potted rose |
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jtill wrote:
| Quote: | Hey all, dropped by LOWE's , "YEAR AROUND DORMANT OIL" 11.98 per quart.
I checked contents. CANOLA OIL 98%, Inerts 2%. WOW!
CANOLA is $2.50 qt. at Kroger.
Joe T
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Hi Joe
I haven't ever used Canola oil, only vegetable oil, so use your own
judgement. And, yes, the price dif is amazing....why would you spend
all that extra money on dormant oil, when vegetable oil (or canola, if
you're going to use it) does the trick beautifully. ( I learnt this
from an old gardener who had used veg oil instead of dormant oil on his
plants with success for years.) I also make up my own white oil (pest
oil) based on vegetable oil to combat scale on the roses. I have not
had to buy dormant oil/pest oil for years. Much more economical - more
money in our pockets to buy another rose plant! Happy gardening, Elsie |
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