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Weird, dark spots.

Posted by sickac none (My Page) on
Fri, Nov 29, 13 at 16:57

Hi!

We have this plant growing in front of our house (possibly damaging its foundations, but that's a topic for another forum...). We really like it and would hate to see it dying. I found a little dark spots on it and it just does not look good. Would you know what that is and how to take care of it?

https://plus.google.com/photos/116445721004889030648/albums/5951802159342600545?authkey=CIar0d3W_OCbQA

Thank you in advance!

Cheers,
sic


Follow-Up Postings:

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RE: Weird, dark spots.

Examine the spots (that look like a colony of raised brown bumps) more closely to see if they are a scale or cushion insect.

Try the Name that plant forum.

I have reposted your link, removing the space that generates for multiple-line image URLs, rendering the image unviewable.

Here is a link that might be useful: brown spots on tropical-looking plant


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RE: Weird, dark spots.

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Sat, Nov 30, 13 at 13:37

Yeah, those look like brown soft scales. Plant is probably not damaging foundation unless foundation is fragile or vulnerable in some way to begin with. Which would mean it needed to be beefed up anyway.


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RE: Weird, dark spots.

If it's scale, the individual bumps should be easy to remove with a fingernail.

And if it's scale, the plants are heavily infested. Thus, something is wrong in their environment. Perhaps water, too much or too little?

And where do you live other than in the "northwest?"


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RE: Weird, dark spots.

Hey!

Sorry for delay, I'm in Poland at the moment (brrrrrr....), will be back around Dec 20th and will examine those spots with a greater detail. I live in the Bay Area, and if it comes to rainfall, it's been pretty dry (multiple months without rain) till very recent. I do not water this plant at all, so if it is watering issue it will definitely be lack of water, rather than excess.
I feel a little bit guilty, we bought this place 2 years ago and still working on the house, never really got a chance to spend some time with this plant (would you be able to say what it is?). Anyway, I hope it is not all lost so far, really appreciate all your help so far!

Cheers,
sic


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RE: Weird, dark spots.

  • Posted by bboy USDA 8 Sunset 5 WA (My Page) on
    Sun, Dec 8, 13 at 17:35

Probably Yucca aloifolia. I don't see it as overgrown so much as the foundation shrub right against the house, which now looks all over the place.


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RE: Weird, dark spots.

Hi!

Finally got a chance to take a video of those bumps, maybe that would help to identify them. You can find a link to it below.
Please, let me know if you know what that is, I still hope I can save it.
Happy New Year!

Cheers,
Pawel

Here is a link that might be useful: Video - Scraping bumps off the yucca leaf.


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RE: Weird, dark spots.

Too much motion and blur in video for positive ID, but the way the bumps came off readily without removing any plant tissue would be consistent with scale insect.


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RE: Weird, dark spots.

Looks like scale to me. Did the yellowing of the leaf happen before or after you noticed the bumps? Often scale is an indicator that the plant is unhappy for one reason or another. Could be a change in the water cycle, could just be the seasonal differences. It could also just be a seasonal thing. I get scale like crazy on our camelia in late winter, then the leaves drop and it is pretty much gone till next year. You could be seeing a seasonal thing like that with this.

IF you want to try and get rid of it, you can use a q tip dipped in rubbing alcahol and rub it against the bumps to kill them without doing any harm to the plant. On a large plant like this, that may take a while, lol. A dormant spray of 1 tablespoon of canola oil, a tablespoon of Dawn type liquid soap in a liter sized bottle of water, sprayed on may also do the same. This is a CONTACT poison though, so make sure you hit the undersides of the leaves and any nooks and crannies where these little buggers are hiding.

These bumps are the larval or nymph stage of the scale insect. The adults are little gnat like things. You can help control them with a tangle trap, usually a bright yellow or red piece of plastic painted with a sweet sticky substance. You can get these at most lawn and garden stores. The little bumps are stationary, so easy to kill. The adults are highly mobile, so can move around the neighborhood really easily. Long term control of scale is difficult at best because of this, and the little bumps like to hide in the most difficult to reach places on a plant.

Honestly, watch the plant and see how it does as spring warms things up. This may just be a seasonal thing and no big deal, or it may be a signal of something more problematic. If the latter, find someone local who knows the plant better. Its a beauty, but we can't grow them up here in Seattle, lol. I do wonder though. if this is the same Yucca they grow in the tropics, and eat the flowers. If so, they have a distinctive taste.

For what its worth, Yucca typically are not overly sensitive to drought. Too much water, yes, and also to cold temps. Like most drought tolerant plants, they can also be very sensitive to CHANGES in water regimes, as in if a leaky gutter was recently fixed, a downspout added or removed, timed irrigation turned off, that kind of thing. I don't know though, how hardy this one is in your area, to either drought or the cold you have their.

Overall the plant looks pretty healthy to me. I suspect the yellowing of the leaves I can see is mostly do to the natural cycle of leaf aging and decay, and since it is winter, this is a likely time for the plant to drop old leaves getting ready for spring. The yellowing may not be anything more than the plant trying to "harvest" as much of the nutrients out of those leaves as possible, getting ready to push out new growth and possibly making flower spikes for spring. Evergreens like this typically hold onto their leaves for a set number of years, then drop them like this- first yellowing at the base, then gradually softening and the base of the leaf separating more easily, till it turns brown and falls off naturally.

At any rate, good luck with your yucca tree. I don't see anything to raise too much alarm with it for now, but watch and see what it does.


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RE: Weird, dark spots.

I do not know what to say, really. So, so impressed!:) A little bit embarrassed at the same time... It has been two years and I still know next to nothing about those few plants that we have around. Q tip may be too ambitious to me, but I can definitely spray it and set some tangle traps. I will try to monitor it on a weekly basis, we will see.
Anyway, no matter what, the fact that there are people willing to share their knowledge to that extent - now that is impressive. Thank you very much!!!

Cheers,
Pawel


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