Ask a Question forum: Aucuba japonica Blight on leaves

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Perryville, MD (Zone 7a)
Feb 24, 2018 10:41 AM CST
Hi All,
This is all the same plant, but the left side is almost black, and has a greasy appearance. We had this last year, but not nearly to this extent. The good side of the plant looks perfectly healthy. It is possible that there are two different root systems, but it looks like a single plant. This is about 4-5 feet tall. Any ideas on what got to it, what to do now, and how to prevent it ??

Maryland garden, zone 33/34 near Chesapeake Bay

Thank you, Craig
Thumb of 2018-02-24/CalicoSilver/23ea41

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Name: Carol H. Sandt
Lancaster County, Pennsylvania (Zone 6b)
Peonies Butterflies Region: Mid-Atlantic Hibiscus Daylilies Xeriscape
Hostas Roses Celebrating Gardening: 2015
Feb 24, 2018 10:58 AM CST
Are you certain the problem is disease?

I have many Aucuba japonicas, and they have experienced what I think is the problem you have described and illustrated, especially after winters with extended very cold spells. It has been necessary for me to remove the black portions completely. When not removed completely, mine have sometimes sprouted foliage that lacks the waxy cover that characterizes Aucuba japonica.These leaves eventually died. Such leaves have signalled branches that needs to be removed completely. Completely removing these branches as soon as possible opens up the shrub to sunlight and new growth.

I live on a hilltop where drainage is never a problem, but extreme cold is.
Carol H. Sandt

β€œOnce you stop learning, you start dying.” – Albert Einstein
[Last edited by csandt - Feb 24, 2018 4:06 PM (+)]
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Name: Daisy I
Reno, Nv (Zone 6b)
Not all who wander are lost
Garden Sages Plant Identifier
Feb 24, 2018 4:00 PM CST
I think it happens when the roots get water-logged in winter. Cut off the bad parts and try to improve drainage.
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and proclaiming...."WOW What a Ride!!" -Mark Frost

Perryville, MD (Zone 7a)
Feb 24, 2018 5:09 PM CST
Thanks Carol and Daisy. No, I am not sure the problem is a disease, I was not sure what it was. We had a very cold winter, particularly in early January (as Carol will remember). We have other plants like this around the yard, all in about the same growing conditions, but only this one suffered this way. I thought perhaps it was the cold, or possibly some sort of root rot. It is clay soil, and on a hill, so standing water is not a problem. Sunday I will take a closer look and make sure this is all one plant. If it is two, that does help understand it better. Thanks for your thoughts. Craig
Perryville, MD (Zone 7a)
Feb 26, 2018 10:36 AM CST
We cut down the Aucuba yesterday, but I did not have a camera handy. The image here shows about what we saw. The small branches near the top were woody, and the small core was a black. As we cut into larger branches further down the black core increased, until at the very bottom the largest stocks are very woody, tough, and all black.

After removal, we can see better and much of what is in the original photo is from healthy green suckers from the ground. It is possible that that two large branches are still coming from the roots of the sick plant. We will see if they survive. I cut a couple of the green branches nearby, and those were softer, yellow/green inside, and moist -- like a healthy plant.

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Name: Philip Becker
Fresno California (Zone 8a)
Feb 26, 2018 11:08 AM CST
My thoughts are frost damage.
Frost can act strange.
Like, when is raining on your side of the street, and it's dry on other side of street.
Personally, I would wait until danger of frost is over, to cut it back.
Anything i say, could be misrepresented, or wrong.

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