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A little more then an year ago I got six palm trees (two vases). It was the Californian equivalent of an Areca palm (the guy in the nursery suggested this one after I asked for an Areca for its air cleaning prowess but now I can't recall the exact name).

My forgot-the-species-palm-tree

After some six months it started to develop some white dots. My research showed up mealybugs. But they do not look like any infestation of mealybugs I could find! It does not have the silk-like thing anywhere.

white dots on palm tree

Used to clean them off the plants after I gave up on one of the plants:

white dots on palm tree white dots on palm tree stem

Some zoom in 10x the real width of the leaf is 2cm or 3/4 of an inch. They NEVER move like mealybug does. (The horizontal lightning on this photo highlights the dust too)

zoom in on white dots on palm tree

Week after week I'd spend hours cleaning the white dots. They are very easily removed by a damp cloth or paper towel. I tried spraying everything: vinegar, lemon juice, cleaning products. Nothing took care of it without wiping. I even put a net on the roots and trapped a ladybug that everyone says is the hellhound of mealybugs. It did not show any interest at all.

Also noteworthy, the plants are in a small apartment that has 3 EPA air filters on 24/7.

What is this thing?

More zoom, 10x of the magnifier + 6x camera's optical more zoom

The tip usually dries, but I'm not sure it's related to the disease. I'm a bad plant-parent that usually forgets to water.

The tip, which usually starts to dry

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did the plant get injured somehow (maybe by pruning or knocked) before the symptoms presented themselves? Have you tried repotting in a clean pot with new, clean potting soil? –  Mike Perry Aug 22 '11 at 18:33
    
It's happening on all 6 of the plants. on two different vases, on two separate rooms –  gcb Aug 22 '11 at 21:42
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where did you getting the potting medium from? Only asking, as I think it might have been that that brought in the problem, seeing as you say "It's happening on all 6 of the plants. on two different vases, on two separate rooms" –  Mike Perry Aug 22 '11 at 22:12

7 Answers 7

up vote 8 down vote accepted

Mealybugs are only one of over a thousand different varieties of Scale Insects which vary tremendously in appearance, and it is almost certainly one of these that is attacking your palms -see here and here.

Scale insects, apart from mealybugs, are mostly sedentary creatures (apparently, the females are usually immobile), and they are difficult to control because most types are equipped with a waxy covering which protects them against spraying. However, they can be suffocated with a vegetable or horticultural oil, and a quick online search has come up with the following recipe for a non-toxic spray:

2 teaspoons (10ml) vegetable oil

1/8 teaspoon (0.6ml) washing up liquid

230ml warm tap water

Shake vigorously in a spray bottle and spray the leaves.

There is a very useful article on scale insects by the Royal Horticultural Society here.

I hope this helps.

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followup on this. this didn't work for me :( actually nothing that you 'just spray' worked. after losing a few branches to it and testing several other things, the only thing that works is a cloth damped in vinegar and actually scrubbing them off. this will get the pests out of the leaves and trunks. for the hard to reach spots, mostly on the trunk between each leave, use a ear bud also soaked in vinegar, and after each pass, clean it on the cloth and keep moving. tedious work, but saved my two palms. –  gcb Dec 20 '11 at 23:03
    
I have had some good luck dislodging bugs with a a soapy toothbrush. –  Jonathan May 16 '12 at 17:33
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I have tried with soap and vinegar solution. I have managed to get rid of the bugs… but I have nearly killed the plant (it lost most of its leaves)… So, be careful with that. –  Jacek Konieczny May 18 '12 at 18:25
    
@JacekKonieczny i then used too little... in fact, i used undiluted white vinegar. and it did absolutely nothing to the bugs or to the plants. scrubbing with water had the same effect. In the end, I trashed both plants as the infestation in the impossible to reach places always make the whole plant infestation return. was a pointless effort. –  gcb Jul 30 '13 at 17:31

Your photos definitely look like a scale. Some information gleaned from "The Organic Gardener's Handbook of Natural Pest and Disease Control" (Rodale), Bradley et al, eds:

  • Armored Scales are part of the family Diaspididae. As Mancuniensis says, there are a lot of different species here -- over 2650 according to wikipedia.

  • In warm areas (I would presume this applies to your case too -- indoors), they can produce up to 6 generations per year.

  • The insects' process of building up the armor can take a month or more.

  • Adults are difficult to kill once protected by the armor. You will need to repeat the oil spray application described by Mancuniensis every 7 to 10 days for good control. The idea is to kill the eggs and nymphs because the armored adults are harder to kill.

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This looks like Boisduvals scale to me. You can read more here On plants with hard leaves you can take a scrubby to them and physically remove them. However they tend to shelter deep within the root axils and I have never been able to eradicate them with soap and water.
As I try to reduce the maintenance I have to do on indoor plants I usually get rid of infected plants with problems that cannot be controlled in the long term with soap and water.

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hum. it does look more like it than the previously measly bugs... or is this technically a family of them? Anyway, i observed the same spot for weeks. Was never able to see one of them move. or show any member/antennae/whatever. they all just popped into existence... i'm probably a lousy watcher. –  gcb Jul 30 '13 at 17:34

If you live near a hydro grow shop they will carry a product called Mighty wash. It's like 20 bucks but if you spray every 3 days for 2 weeks it will clear it up, I had the same problem. And your plant will look green and heathy again. It's worth a try.

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lots of my old questions are getting new answers these days... thanks for the suggestion, but those plants are long dead now :( I could take them out by hand using a wet cloth (soap, vineager, i did with everything) but the bugs in the middle of the steams that i had no access to eventually killed them. –  gcb Apr 15 '14 at 22:08

They are scale insects; spray the plant with summer oil mixed with systemic insecticide (Acitamiprid or Imidacloprid) according to the concentration mentioned in the label. Then do a repeat spraying after two weeks. It is better to add some foliar fertilizers to the solution sprayed.

Note: do not use winter oil instead of summer oil. If you have not found the oil mentioned, spray only the insecticide.

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Do you have any references to adding a foliar fertilizer to a pesticide? As a former licenced applicator I think this would not be recommended for any product due to the unknown interactions between the fertilizer and the other ingredients –  kevinsky Jul 15 '14 at 15:57
    
what exactly are winter/summer oil? all my searches on that turn up car engine oil discussions for winter/summer. –  gcb Jul 16 '14 at 17:28
    
Kevinsky...this is an indoor plant, yes? Are the dormant oils used inside? –  stormy Mar 5 at 21:11

Have you tried NEEM? This is a pretty great insecticide. Don't worry about total kill. Scrubbing these guys off even with water will hurt the leaves...With vinegar? Alcohol? Ouch. The adults have a bit more protection, but your goal is to get the scale 'under control'...your watering technique is far more preferable to watering a little everyday. Make sure to dump the water out of the saucer and take your plant into the shower, cold water and allow the water to wash off all the leaves, soak the soil then allow to drain before taking back to it's normal location.

Spray with Neem, please read the label...at least 5X! Grin, that is the main message we learn in pesticide school. A good place to do this is after it has been watered and washed by the shower and after allowing to dry and drain. Spray while in the shower...always use sterilized potting soil for plants in pots. Did you use garden soil? Any other house plants with scale? If you used garden soil, this is where you got your scale starts...

Don't physically try to remove the scale. Spraying at least once every two weeks when you can still see these critters is plenty. If you don't see any, please stop using the pesticide. Also, spray the top of the soil. If you have birds don't spray anywhere near them or in the same room.

I'd replace the soil, put in a clay pot versus plastic, all soil, no gravel at the bottom, a saucer and try to get the bottom of the pot up off the saucer or surface to increase drainage. Fertilize sparingly. Plants inside need to be treated like plants outside in the shade. If you are a novice the best fertilizer is Osmocote, twice per year. If you know plants and are able to see when they need fertilizer, the symptoms of deficiency as well as excessive nutrients, then use organic fertilizers. Even a watering with fish emulsion once or twice per year is a good idea as this stuff has been shown to make plants a bit hardier. If you have equisetum (horse tail), collect a bunch of the tops, dry, powder in a cusinart or blender, add to water and the silicon helps to boost a plant's hardiness.

Watch all your houseplants for scale as it is now in your environment. Just make it not so nice to live for scale...I prefer neem to soap sprays and dormant oils. Both help, but Neem is a better control, in my opinion.

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I've had every kind of pest and didn't want to trash my babies. The only thing that has worked for me is to take them, pot and all, if small or if large, out of the pot wash roots and submerge them completely under water. I have a small creek by my home so it's convenient.

Tubs will work just the same: bury them completely under the water, make sure not one leaf is sticking out and leave them for up to 4 hours.

Believe me, it's way better than spraying everything under the moon on them. That just weakens the plant and it loses leaves. Repeat if necessary for baby bug eggs being hatched.

I have over 100 houseplants for 3 years now, fought every kind of bug and haven't lost one yet: it's the only way to go

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