"Natty Dread" wrote in message
...
"Gail Futoran" wrote in message
...
"Natty Dread" wrote in message
.. .
[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