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Best Powdery Mildew Remedy

Posted by ocbrian 9 oc/so cali (My Page) on
Thu, Jun 18, 09 at 9:09

What do you think is the best solution to make at home to control powdery mildew. With the June gloom still hanging around here everyday, half of my roses have mildew. I saw a lot of solutions and chose one last month which was water, baking soda, dish soap, and vinegar. After spraying my plants with the stuff all my leaves turned yellow and brown and fell off the bush(I think it was the vinegar since that was the only recipe I caw with the stuff). Sadly half my roses foliage looks horrible and I felt like crying, but now today they have new leaves coming in everywhere. So please let me know what you do that is safe and works. Also, I do I upload pictures? Thanks!


Follow-Up Postings:

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RE: Best Powdery Mildew Remedy

Vinegar is sometimes used as a herbicide. Not good for rose leaves, but I see now a recipe for a "rinse" using a weak vinegar/water solution. The rest, without the vinegar, should work fine, but you have to make sure the plants are well hydrated before applying anything.

You can also try a solution of 1 part milk to 9 parts water. Some have even used just washing down the leaves with water, but the leaves have to dry out.

See the link below for info on posting photos. You have to first upload them to a site like Photobucket.com.

Here is a link that might be useful: how to add pictures of my garden under construction


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RE: Best Powdery Mildew Remedy

I just thin the plant so there is as much air flow as possible (and remove the bad looking stuff). One of these days the air will dry out and our roses WILL recover. Until then, try one of the methods recommended here if you must, and good luck.


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RE: Best Powdery Mildew Remedy

Messenger works well for me in my no-spray garden, but is expensive if you have many roses. Mostly I use plain water spraying of the leaves as frequently as possible in the morning. PM doesn't like to get wet. Also, in our area, PM is a nuisance but the roses grow through it and it goes away by itself.


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RE: Best Powdery Mildew Remedy

Curlydoc,
If you really like Messenger, you might want to buy now for future use. A recent mass email from Rosemania talked about it no longer being made by Eden Bioscience. See link below.

Here is a link that might be useful: about Messenger's availability


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RE: Best Powdery Mildew Remedy

Darn, I quickly went to the site and they're sold out of all quantities. Too late! Those in the know have gobbled it up. The early bird gets the worm. Thanks for the post. Other rosarians saw it before I did.


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RE: Best Powdery Mildew Remedy

With home remedies you have a greater risk of burning. Be sure the plants are well hydrated, and spray in the morning.

I never saw a mixture of baking soda and vinegar suggested by any responsible source. Also adding soap to baking soda makes no sense and it redoubles the harmful sodium.

You could do 1 TB of baking soda/ gallon, but the commericial products Remedy and GreenCure would be preferable and equally safe. See also Cornell Mixture on the Organic Roses FAQ.

Daily hosing off should be effective


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RE: Best Powdery Mildew Remedy

If it is a mature rose, and mildews consistently, the best remedy is a shovel.
Life's too short -- and there are too many roses that do not mildew -- to grow those that do.

Jeri


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RE: Best Powdery Mildew Remedy

Doesn't the Cornell Formula contain soap and oil? I think I would pick soap (Ivory or Safer's insecticidal or some mild liquid ) over oil.


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RE: Best Powdery Mildew Remedy

  • Posted by maryl Z7 Okla. (My Page) on
    Thu, Jun 18, 09 at 14:50

Years back when the "harmless" baking soda solution was first being bandied about I used someone's "Cornel recipe" from this forum and the foliage on most of my roses just fell off. Of course there was no Powdery Mildew any longer so I guess you could say it worked. I think the problem with some of these home remedies is that something gets lost in the translation. The next time I opted for "Remedy" which a company (Bonide) had done the R&D on in more then just their own back yard. It worked on mild cases of PM (although it does nothing for BS). Roses with a real lack of PM resistance are now gone from my garden, but when I had them and needed to ensure PM control on more then minor infections I used a product called Rubigan. I don't believe it's organic, but it works.


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RE: Best Powdery Mildew Remedy

Dr. Horst did include a small amount of Safer's Insecticidal Soap (potassium soap vs. the sodium in dish soap) as a surfactant (spreader). This link mentions 1/2 TSP soap/gal. It spreads and sticks the bicarbonate. Horst found potassium bicarbonate more effective than baking soda. The commercial products would include a spreader-sticker.

Here is a link that might be useful: ATTRA on bicarbonates.


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RE: Best Powdery Mildew Remedy

MARY SAID: "Roses with a real lack of PM resistance are now gone from my garden, but when I had them and needed to ensure PM control on more then minor infections I used a product called Rubigan."

Same here.
Rubigan, as a PREVENTIVE, did work.
There is a biological product: SERENADE
Not so easy to find, but it is somewhat effective. Again, as a preventive, rather than an eradicant.

ERASE (Eco-ERASE) is somewhat effective as an eradicant, but it is an oil, and I would not spray any oil on Southern California roses at this time. It's still cool here at the coast, but temperatures are rising inland.
I have had oil-treated foliage burn at temps not much over 75 degrees.

Like Mary, we do not keep roses with a real susceptibility to mildew -- or, for that matter, to rust. It's not worth it.

Jeri


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RE: Best Powdery Mildew Remedy

To me, the best remedy has been to place the roses in the right spot (i.e. good air circulation) and to select those roses that are very resistant to mildew in my climate.

Now mildew is virtually unknown to my roses, I hardly see even one leaf affected :-)


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RE: Best Powdery Mildew Remedy

Thanks Michael, I thought that's what it was for. A little goes a long way...


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RE: Best Powdery Mildew Remedy

I too have been trying a milk solution on some newly planted roses. It seems to be helping. It definitely did not burn any leaves.


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RE: Best Powdery Mildew Remedy

  • Posted by maryl Z7 Okla. (My Page) on
    Thu, Jun 18, 09 at 19:57

I also meant to mention that when I was having so much trouble with PM a rosarian told me that dry roots can contribute to the rose being more susceptible. Since our springs are usually rainy enough to suit Noah himself (and when PM is most prevalent here), I thought that this couldn't be my problem. Well, duh. When I finally pulled all the roses out from this border I found that even though the soil outside the border was wet it was barely moist where the roses had grown. Why? The rose border was partially shielded from any rain by a roof overhang. You get 5 inches of rain during the day and you wouldn't think that you still needed to water, but in this case the roses may have been bone dry. This caveat would also apply if you have tree roots or other thirsty plant roots sucking up the main part of the moisture. I have retained one fairly PM susceptible rose (Chrysler Imperial) but have it in another location with assured adequate moisture, and the odious amount of PM it used to suffer is no more.


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RE: Best Powdery Mildew Remedy

Over the years Nova has always worked for me, but you can
do nothing and let your roses suffer until temps reach and stay above 80 degrees. At those temps, mildew can't survive.


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RE: Best Powdery Mildew Remedy

Great, I think I will try either just spraying every morning with water or I will try the milk and water (I believe I just saw this on Martha Stewart). Thanks!


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