Trouble with oleander

Hello Dave Gardeners,
I have another problem, this time with an Oleander tree.
The leaves are turning black . I have been told that , "it just happens, just cut it back", but I would like to know why.
I have sprayed it a couple of times and trimmed it, but it continues.
There is an asparagus fern growing at the base of it and I am starting to wonder if the roots of the fern could be choking the oleander out. Both have been planted for a few years now.
The roots of an asparagus fern are fierce-to say the least .
Could I dig out part of the fern without hurting the Oleander????
Any suggestions

Thanks,Mary

Are the leaves black but otherwise still look alive (looking like they're covered in something black, but the leaf shape hasn't changed), or are they turning black looking like they're shrivelling or dying? There are two possibilities I can think of--one would be that it's affected by scale (or aphids) both of which secrete honeydew which can lead to black mildew on the leaves. The other possibility is bacterial canker which would make the leaves look more dead, and you may also notice it affecting the stems as well. Canker is going to be more prevalent in wet conditions so I've never seen it on oleanders out here, but I have a book on pests of trees/shrubs which says that oleander is susceptible to this. A picture of the affected leaves/branches would help figure out if it's one of these problems or something else entirely. Neither of these conditions have anything to do with the asparagus fern, and unless the oleander is a very small plant and the asparagus fern is huge I don't think the asparagus fern roots should cause too much problem. However, I found asparagus fern to be a huge pest at my last house--it spread everywhere so removing it might not be a bad idea anyway!

Mary, did you start the Oleander from seed, or purchase it as a plant? Do you have it inside, or outside? I don't know that either of these would have anything to do with your problem, but just curious more than anything.

Jeanette

Thanks for the replys.
The leaves look like there is a black sooty mold on them, and just "hanging" there. It is a well established outdoor plant.
I hate to cut the thing all the way down, so I am just waiting and watching.
I have sprayed it with the same thing I use on my roses, but it did not help the affected leaves, but the new growth looks good. It looks like the same thing on a "Tulip tree" which is not in good full sun like the oleander. I just wonder if it is not getting enough good sun.?????
I have seen two others that get more sun and they look good. I guess I'll just have to wait for spring and hope for the best, keep the bad leaves off of it, and spray.
I would just like to know exactly why it happened, that way I know what to watch out for.
Mary

Mary

Have you tried spraying real hard with the hose?

The black stuff on the leaves can be hard to get rid of--spraying really hard with the hose can help, or a bit of soapy water. Spraying with antifungal may kill the mildew so it doesn't grow anymore, but until you wash it off the leaves they will still look black. The key though is to get rid of whatever was making the honeydew that caused the environment to be hospitable to the mildew because otherwise it could come back and affect your new growth too--if it was aphids then soapy water or a hard blast from the hose will probably do the trick but if it's scale, they're a bit harder to get rid of, as I said on mine the easiest thing to do was cut out the branches that had lots of scale on them. Scale will look like little black or brown bumps on the branches--it's pretty easy to see.

It sounds to me like whatever it is that you can't do anything about the old leaves, but, since the new leaves do not appear to have it, due to the rose spray, if it were mine I would take off the old leaves, spray it down good, including the stems, with the rose spray and continue with that per the directions, or get some Bayer 2 in 1 rose care and try that. It is a systemic plus the rose fertilizer, but that won't hurt them.

I have an Oleander in my bedroom that is about 3 feet tall with several side branches. It is 2 years old and has not bloomed yet. I should have but it outside over the summer and it probably would have. My daughter has one that she started from seed about the same time and it bloomed this year. She lives in Seattle and is the same zone as you are. I'll bet she never thought about planting it outside.

Thanks again for the replys. I will continue to spray and take the bad leaves off.
Mary

OK, I forgot. How do I mark this as solved.
Mary

You can't in this forum--it's just the ones like ID and trading that have closed/solved options.

I see the problem of this black mildew or whatever it is on oleanders is quite common. Living in Bermuda we have lots of mildew and fungus, as the weather is quite humid.
My oleander hedge has been planted for years and suddenly a few months ago I noticed black appearing on the leaves. I was away for a month over Christmas/New Year and since my return see that some parts of the hedge have actually died. It is very widespread. all along the front of my property. (The hedge goes up the sides, too, but so far the problem is only in the front). We have to be careful with water in Bermuda, so using the hose extensively is a No-no. I have been spraying with Neem, but will try the soapy water route now. I'll be 71 in less than two weeks, so this is taking a lot of my energy!

The oleanders they have planted along the freeways here get covered with that black sooty mold fungus, yet it doesn't seem to hurt them any...they keep growing and blooming like crazy.

Like mentioned above, try using one of the insecticidal soaps on it, and really drench it.

A friend of mine gets the same problem and we've sprayed them and it seems to work, but we had to do it a few times.

Are you sure that isn't black aphids you have? Altho, I wouldn't think Oleanders would attract aphids. Maybe Scale, but that doesn't sound like any scale I have ever seen either.

Jeanette

Sooty mold. Doesn't hurt the plant but looks bad. Aphids usually the cause of the sooty mold.

I think it's probably scale not aphids--scale also secretes honeydew also which is what the sooty mold grows on. I've never seen aphids on my oleanders, but I have found scale on numerous occasions. Unfortunately scale is harder to kill than aphids. The key to keeping the sooty mold from getting worse is to get rid of the scale (or aphids if it's them instead), otherwise it's just going to keep coming back again and again. If you can get rid of the scale, then it's just a matter of washing the sooty mold off the leaves (easier said than done though--it's stuck down on the sticky honeydew, so if you're limited in your water use and if it hasn't affected too many branches it may be easiest to prune out the sooty parts)

Don't you use oil to suffocate the scale? Neem, or Canola? LOL I would say almost anything would work. Jeanette

I thought the "diseases" section in this link was pretty good. ck it out. Somewhere recently here on DG, there was a good thread concerning diseased oleanders but I couldn't find it. I know that in my area they have begun replacing the oleanders along the freeway because they're suffering from some terminal disease. Mine have not been affected but supposedly it is a matter of time.
http://edis.ifas.ufl.edu/MG348

If I find it I will post here and maybe some kind soul will remember it and post it, pls?

Those along the freeways wouldn't be covered with vehicle emmission would they? When I lived in Seattle I lived near Sea-Tac Airport. I had 2 huge Madrona trees that had died. I finally worried enough about their falling on my house, or the neighbor's house, that I called 3 different arborists about why they died, and taking them down. They said they were the biggest Madronas they had ever seen and the only thing they could think of that would kill them like that was the fallout from the airplanes and/or the noise from them.

Jeanette

I think the terminal disease you're referring to is oleander leaf scorch which is a bacterial disease that's transmitted by some insects. The symptoms described in this thread are not consistent with the symptoms of leaf scorch, Mary's description definitely sounds like sooty mold. The leaf scorch disease makes the leaves turn yellow and eventually die http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7480.html

thanks ecrane, leaf scorch is what I was referring to. Also, I agree that it seems that the symptoms described here are sooty mold. I just wanted to mention the leaf scorch for reference.