Roses forum: Rose Problem

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Name: Shannon
Burkeville,Va (Zone 7a)
The House on the Hill Gardens
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Shannon
May 24, 2012 7:46 AM CST
My boys( Liam & Seamus ) and BF gave me a couple of roses for Mom's day. But,one of them is getting a greyish spots on the leaves Glare I can wipe it off but,it comes back. we have been getting alot of rain lately so Im thinking a fungus.

Help what can I do for her ? I already fed with the Bayer granular food. Is there some
thing I can spray on all of them just in case Whistling They are in sun for about 5 to 6 hrs a day
The horse is God's gift to mankind. ~Arabian Proverb
Name: Toni
Denver Metro (Zone 5a)
Whiskey Tango Foxtrot.
Charter ATP Member Irises Salvias Xeriscape Birds I was one of the first 300 contributors to the plant database!
Garden Ideas: Master Level Garden Procrastinator The WITWIT Badge Region: Colorado Enjoys or suffers cold winters Cat Lover
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Skiekitty
May 24, 2012 9:34 AM CST
Powdery Mildew. Here's what I posted on a different thread. :)

Did some quick research on powdery mildew. Here's why watering makes the white go away:
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http://scvrs.homestead.com/MarchMildewMalady.html

Powdery mildew affects roses grown in dry climates and is common in much of California, including the Santa Clarita Valley. Caused by Sphaerotheca pannosa var. rosae, it forms a white, powdery film on the leaves, stems, and flowers of infected roses. Young peduncles, sepals, petals, and stems become twisted and distorted and new growth buds and growing tips may be killed.

Powdery mildew is common in the spring and fall when warm days are followed by cool, damp nights. Spore maturation and release usually occurs during the day when the relative humidity is low. At night when temperatures drop and the humidity increases, spores germinate and the fungus penetrates the plant's surfaces. Spores need low humidity, warm temperatures, and dry leaves to mature and be released, hence the advice to hose off the leaves of infected plants during the day. The only caveat being that the plant must be dry by nightfall.

Again, prevention is the best cure:

Plant resistant rose varieties
Plant them far enough apart to allow lots of air circulation
Plant in full sun
After pruning, strip the leaves from your roses and discard to the trash
After pruning, use a dormant season horticultural oil spray
During optimal growth conditions, wash all surfaces of the plant with hose water.
Do so early enough in the day that the leaves dry out before nightfall.

One of the easiest ways to control powdery mildew is to give your roses a thorough wash at least two mornings a week. A morning bath raises the humidity so spores can't mature. Free water left on the plants also discourages spore maturation. Plants must be dry before nightfall so residual moisture does not provide favorable conditions for spore germination.

Powdery mildew is attracted to lush, new growth. Rosarians growing for spring shows feed their plants heavily early in the year in order to have roses ready to cut. If you are not pushing your plants for a show, try cutting back or postponing the early spring feeding.
Roses are one of my passions! Just opened, my Etsy shop (to fund my rose hobby)! http://www.etsy.com/shop/TweetsnTreats
Name: Shannon
Burkeville,Va (Zone 7a)
The House on the Hill Gardens
Roses Butterflies Seed Starter Enjoys or suffers cold winters Birds Peonies
Sedums Hostas Cottage Gardener Echinacea Clematis Irises
Image
Shannon
May 24, 2012 10:17 AM CST
Thanks...Rose proberly already had the mildew. I have it away from the others and will work on her
AM baths
The horse is God's gift to mankind. ~Arabian Proverb
Name: Steve
Prescott, AZ (Zone 7b)
Region: Southwest Gardening Roses
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Steve812
May 26, 2012 10:53 AM CST
If you bother to bathe your rose in the morning anyway, I might suggest mixing into a gallon or two of water a few drops of Dawn or your favorite dish detergent, and either potassium bicarbonate - sold online as Green Cure - or two teaspoons of sodium bicarbonate AKA baking soda. If the rose is in a pot, you might tape newspaper over the top and immerse the whole thing upside down in a big can of the mixture.

There are more expensive cures for fungal disease sold at Rosemania, but IMO that way lies madness.

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