White powder on roses

vdixitJuly 24, 2005


One of my rose bushes has a white powdery substance on its leaves. I am guessing its some kind of fungus. What should I use to get rid of it? Also their are other rose bushes around this diseased one. Should I also treat these to prevent a similar outbreak? I think I remember reading about some home remedy for it, perhaps baking soda solution or something. Tell me if I am correct and what concentration I should use. I would really prefer using a home remedy rather than buying expensive store chemicals or antifungals.

Thanks for your help.


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pitimpinai(z6 Chicago)

When I rinse my milk jugs, I sprinkle the water on my rose leaves. It seems to help prevent fungal infections. I have not seen any powdery mildew this year and only one leaf with black spots so far.

The Garden Experiments have a thread on using milk & water and another using corn meal.

Here is a link that might be useful: Milk & water to fight mildew.

    Bookmark   July 24, 2005 at 6:37PM
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Anyone else has any other suggestions? I looked closely and another one of my roses has the same stuff on it.
I will definitely try the milk.

    Bookmark   July 25, 2005 at 8:40PM
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I don't know what part of WA you are in, but if you have a little rain every few days and the roses stay wet for long periods, this is what can promote mildew. If you water them, don't water at night, water in the morning so things can dry up quickly. They should be in the sun too.

    Bookmark   July 25, 2005 at 10:20PM
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rhizo_1 (North AL) zone 7

I am going to guess that you have just started gardening, since you've been so blissfully unaware of the dreaded powdery mildew! Believe it or not, it is a plant disease that is almost entirely avoidable, if we take some proper steps in the first place and then throughout the year.

First of all, do a little bit of research before you purchase your next rose or garden ornamental. Some are notoriously prone to PM, while others will be cited as 'resistant'. Give your roses plenty of elbow room, and full sun conditions. Good air circulation also helps prevent PM from taking hold.

Attached is a very good fact sheet with plenty of 'home remedies' for you to try. Those, along with prevention, should go a long way avoiding another occurance next year.

Here is a link that might be useful: PM Fact Sheet

    Bookmark   July 26, 2005 at 8:33AM
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Most of the roses in my yard get full sun in the summer. You are right about my being a brand new gardner. I recently moved here and the house I moved into already had these roses for 2-3 yrs (my guess).
I will try not to water them in the evening and will prune some to give them more room.
Also what kind of fertilizer/plant food should I use to get maximum bloom and when should I fertilize?

    Bookmark   July 26, 2005 at 1:05PM
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rhizo_1 (North AL) zone 7

You should concentrate on getting rid of the powdery mildew first. Do everything you can to grow healthy plants in a healthy soil and you won't need to worry about fertilization too much.

Over fertilization is one of the factors that can contribute to PM, by the way. So easy on the nitrogen. Have you visited the Rose Forums here in Gardenweb? There's several of them, at least two on the specifics of rose culture. You could learn a great deal in there just by reading over old postings that ask questions that you may have on the tip of your tongue. And if you do a search in one of those forums using the key words like 'best fertilizer'....you will probably come up with many many old postings about that very subject.

    Bookmark   July 26, 2005 at 3:02PM
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rhizo has given you lots of good information. When you go to the Rose Forum, look at the green FAQ at the top of the page. Click it for answers to questions you may have.

rhizo is also correct about plants crowding around the roses. They do like "elbow room" which gives the air circulation they need.

Have fun with the roses!

    Bookmark   July 27, 2005 at 3:21PM
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