Hydrangea leaves have brown spots on them

moshie01August 7, 2011

My hudrangea has flowered beautifully this summer and I've done nothing to it. I just noticed today that the several of the leaves have brown spots on them. Any ideas what this could be from and what I can do about it.

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Here's a picture of the brown spots on the hyndrangea leaves

Here is a link that might be useful:

    Bookmark   August 7, 2011 at 5:22PM
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luis_pr(7b/8a Hurst, TX)

It looks like a fungal infection called leaf spots, caused by too much humidity and-or overhead watering. I would try to control it by making the environment less humid and using good cleaning practices.

There is no way to control humidity from storms but you can control waterings by making the sprinkler water early in the mornings. If you do overhead watering by hand, you can water the soil instead early in the mornings. If your mulch is often moist or wet, you are watering too much. You can switch to water when a finger inserted to a depth of 4" feels almost dry or dry. Separate shrubs from each other to improve air flow, which will reduce humidity levels.

You can also throw in the trash plant debris found under the bush, replace the mulch with new mulch when more than a third of the leaves are affected, dispose in the trash all the dried out blooms and dried out leaves in the Fall.

You can also try to use fungicides but they can be expensive and we are so close to the end of the growing season (when the leaves dry out anyway) that it is a toss as whether one should apply it or not. I guess if you have a considerable number of leaves infected, you should replace the mulch (it is probably full of spores) and spray sulfur-based fungicides on the leaves (top and bottom) as well as in the stems. If you have an organic regimen in your garden, consider applying a copper fungicide. Affected leaves will not be cured back to all green by fungicides. A drip irrigation system can help reduce this problem too.

Note: in order to minimize spread of the fungal infection, it is best to throw away in the trash the dried out leaves, not in the compost pile (if you have one). Do the same with the spent blooms when you deadhead (throw them in the trach).


    Bookmark   August 7, 2011 at 7:57PM
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Thanks for the information! My hydrangea leaves & stems have them, too. I live in FL, where it's already humid, but this year we had a "two hundred year flood". I'm hoping by next year, they will have had a chance to recover.

    Bookmark   October 4, 2014 at 3:31PM
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luis_pr(7b/8a Hurst, TX)

Oh, wow! I was unaware that it was raining a lot in parts of FL. It has not made the news yet. Out of curiosity, in what part of FL are you?

    Bookmark   October 4, 2014 at 4:05PM
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