Hydrangea leaves are getting yellow with rust spots

vika(7)July 21, 2009

I planted 3 "All-Summer-Beauty" Hydrangeas this spring in different sun-locations. I fed them with acid in the spring, and they looked amazing till the summer came. At first flowers started get green and dry, and then some of the leaves got yellow with rust spots on it, I thought that maybe the sun and the heat in June was unusually hot for this area and it hurt them, but in the July we got really cool temperature for this summer and spots on leaves are still in progress. What could cause these burned, rusty spots on leaves and why do they get yellow? And when can I deadhead those half-dry flowers? Are they going to bloom this year again if I do it in July?

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I just added an image of my hydrangea's leaves
thank you...

Here is a link that might be useful: image of hydrangea's leaves

    Bookmark   July 21, 2009 at 1:50PM
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IanW Zone 5 Ont. Can.

Your Hydrangea has Cercospora leaf spot.

    Bookmark   July 22, 2009 at 12:07AM
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Thank you for your help ians_gardener!
Is there any way I can fix it?

    Bookmark   July 22, 2009 at 1:37PM
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IanW Zone 5 Ont. Can.

You could try a fungicide, but it is hard to eradicate or control once it gets a hold. It doesn't hurt the plant, just makes it look a bit unsightly.

It may not show up again next year, depending on the weather conditions etc.


    Bookmark   July 22, 2009 at 9:36PM
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laura55(z8 SC)

Hi, excuse me for jumping on this thread, but I have the same problem. I live in the Charleston SC area and this forum helped me last year by diagnosing the spots as Cercospora. I bought an fungicide (Spectra Immunox) and have faithfully been spraying my hydrangeas per the directions, every 2 weeks since mid-May. Although the spots are not as plentiful as last year, the color of the leaves is awful. Very sick and pale looking. Washed out. I'm regretting I ever sunk the money into these plants because they are very sad looking. They looked great when they were in bloom. They are 3 years old. Here are pictures. Do I need fertilizer? Are they getting too much sun? (Direct till 1:30) Unfortunately, it is the shadiest part of my yard. Help.

    Bookmark   July 28, 2009 at 11:53AM
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Not sure it is circospora, but it looks like the beginning of it. Keep in mind Hydrangeas like shade, and lots of water. Copper fungicide used as per directions will control this outbreak. Follow up faithfully every three to 4 weeks, and pick off affected leaves. Rake up and remove all fallen leaves as that is how it is spread. I hate circospora. My plants have been perfect and disease free for ten years. I am in the Pacific Northwest (lots of rain)so I had a bad outbreak of it last year. Water from below also, very early in the morning. I hope this helps.

    Bookmark   July 28, 2009 at 8:10PM
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laura55(z8 SC)

Norma2009, thanks for your advice. I also saw your posting on another hydrangea question, whereby you mentioned a systemic fungicide called Ferti-lome. Are you saying that both measures should be taken.....that AND a copper fungicide? What is a "copper" fungicide? Guess it's different than my Spectra Immunox? Where do you find those products? Like I said, the Immunox has made a very good improvement over what my hydrangeas looked like last year at this time, but the overall leaf color is pale green and sick looking. Do you think a fertilizer would help? I have to admit, I'm afraid they are getting too much hot sun (till 1:30). I have been very good at reducing the overhead watering I've done this year. Sorry....so many questions.

    Bookmark   July 30, 2009 at 5:52PM
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Unless the outbreak is very severe, I would not bother to treat for cercospora in a home garden. This tends to be primarily a nursery issue and most plants in the landscape will outgrow it. Just practice good sanitation and avoid overhead watering. Immunox is registered for this purpose (control of cercospora leaf spot) so I would not see the need to use a copper based fungicide as well. FWIW, I work in a nursery and bring home various unsalable or returned plants and nurse them back to health. Without exception all of those hydrangeas that have been afflicted with cercospora leaf spot show no sign of it the following season.

The above plant does look extremely chlorotic (but otherwise relatively healthy) and a fertilizer may be advised. Often, less acidic soils do not allow proper absorption of iron, one of the primary causes of chlorosis, and acid lovers would benefit from chelated iron or a fertilizer for acid loving plants. These typically have iron supplements included.

FWIW, sun only until 1:30pm should not be too much, although SC sun is much more intense than mine up here in the PNW. Your plant does not show obvious evidence of scorch and if it is not wilting excessively, it is probably sited OK.

    Bookmark   July 31, 2009 at 11:15AM
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laura55(z8 SC)

Thanks for the info,Gardengal. Unfortunately, I checked for responses first thing Friday morning and didn't see any, then forgot. Now I am kicking myself because I already bought and applied a different fertilizer. I had went to a hydrangea website that suggested Osmocote so I mixed some in the soil yesterday. It is 19-6-12. Previously, a neighbor had suggested something with iron like Miracid, and instead I went with what the hydrangea website said. I even saw the chelated iron at the store. Oh gee. I'd probably be overdoing it if I added that now, wouldn't I? (The hydrangea website I looked at actually said one shouldn't fertilize after August because the plant is preparing for dormacy.)

FYI, I had the soil checked by Clemson Extension 3 years ago and the ph was 5.1. I had pine straw back then, but switched to mulch last year. Also, I have had leaf spot every year since I planted these plants 3 years ago. I attribute less spots this year to being proactive with the Immunox and minimizing overhead watering.

    Bookmark   August 2, 2009 at 7:52PM
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