diagnose brown leaves

I have three flowering (not yet actually flowering) hydrangeas in containers in my courtyard, which is generally very shady and sheltered. For the last three years, the hydrangeas seemed to be growing pretty well, though the one which got the most sun grows less than those which get more sun. But this summer, about a month ago, the leaves of the sunniest one started to turn brown, and then the middle one, too, and now all three have brown leaves. At first I thought it might be sunburn, but the conditions haven't changed since they were planted, so why just now? There has been root rot in other containers in my courtyard, but these leaves are not wilting, just turning brown.
Any diagnoses? HELP!
P.S. Is there a better place to post this inquiry where I could include a photograph?
KTW
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It is most likely a fungal disease. Here is a like to a wonderful article, with pictures, on diseases of hydrangeas: http://www.aces.edu/pubs/docs/A/ANR-1212/ANR-1212.pdf
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"Vox Humana" wrote:

One of the pictures looks like that black spot fungus that grows on roses.
One of the treatments for black spot on roses is suggested by mixing a bottle of water with a teaspoon of baking soda and a teaspoon of cooking oil. I tried that but my squirt bottle tended to get all choked up for some reason and all the leaves ended up being cut off.
I had tried some 12-10-5 vigoro tomato food on the roses with no visible immediate success. I then noticed that the rose food at the store had a high content of potassium. So i chopped up four banana peals in a blender and then put the whole goo into the soil at the base of the roses.
That worked wonderfully. A month later, leaves bloomed, and a full set of roses started blooming.
Also, I've read that chives will help deter the black spot on roses, so I've planted some chive around the base of the roses. I've not had any success at all with planting chives though, so I cannot say one way or the other if that is a good suggestion for your problem. But it might be something that you can do searching via google on by typing in the keywords, the name of your plant, etc. When I was looking for black spot help for roses, I was doing searches for "black spot"+rose+organic and I pulled up a link about the baking soda and cooking oil. While I can't say that was any help for me, maybe someone else that has actually gotten a squirt bottle to work with such a concoction might be able to comment. Since bananas hold a high content of potassium and I've read some stuff about using banana peals for potassium I decided to try it and it worked fabulously. But ALL the leaves with the black spot were cut off first before I had an opportunity to witness if it would work while black spot still infected the leaves.
One thing that I keep in mind when is that usually infections are caused by a deficiency of vitamins or minerals. The same is true for humans as anyone will tell you that you should have some kind of vitamin C, especially on long boat rides or visits to other countries. The folks back in time used to take 1 orange for each person that came over to the United States when it was being colonized to prevent scurvies and various other ailments.
I don't know nothing about nothing, and I don't have a clue about those hydrangeas, just passing along some information.
--
Jim Carlock
http://www.microcosmotalk.com /
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wrote:

I've had pretty good luck using the baking soda/oil/water spray that you described to control black spot on roses. I have also used it for control of other funguses also. It seems to work better preventatively; once I've had an all out fungus outbreak, it doesn't work as well as other items (for example copper solutions seem to work better to control blight on potatoes/tomatoes once there is an outbreak).
One of the keys with not clogging the sprayer is to fully dissolve the baking soda in a cup of warm water and then add that to the sprayer and then fill with water (the trick being getting it fully into a warm water solution rather than adding the baking soda directly to the sprayer). It doesn't seem to precipitate out again when it cools.
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Thanks, Ally.
Yes, I've read that it's used successfully as a preventive measure and that other measures are needed for full outbreaks. For some reason that slipped to the back of my mind and I forgot about it. I'll have to try that heating with a cayenne pepper solution. Them silverleaf whiteflies are vicious.
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