Question
Hi Will, Well, the pest is back...it seems that it comes back every six
months....the plant is in a huge pot of mostly water with lava rocks and a
chunck of soil at the bottom for nutrition.  Symptoms:  Black spots, not many,
but they are tarrish, and sticky.  I see a lot of tops of the stems yellowing
from the top down.  I thought I had success with a pesticide last spring, and
the plant thrived outside throughout the summer.  Now it is full and beautiful
again, but the tops like I said, are yellowing and it seems to be having a
tough time.  We had spoken before about there being a tiny varmint that was
nearly microscopic in size and that to the naked eye looked like a sooty dust.  
Well, as I recall, it did in fact start with this tarrish black substance last spring
and seems to be growing back again.  I will try to send a picture asap.  As you
know, I am in germany, and thank you for your help in this matter.  I see my
papyrus as a kind of reminder of my life in NYC where I had huge and
beautiful and varied sorts.  This one is just the plain gargantuan
one....without the fuzzy leaves, just the finger like ones.

Thank you for your expertise.  Again, I know you need a picture, and I will do
my best to borrow a camera.

All good wishes,
Tara

Answer
Hi Tara,

From your description, I suspect that you have a scale insect infestation.

Scale can be hard to detect. When they are young, these sucking insects are slightly oval, slightly raised, translucent bumps about an eighth of an inch long. They can be found along stems and on the undersides of leaves. They don't look like bugs and don't appear to move. As they get older, they develop a hard, dark brown shell and look like a small mole. As the infestation increases, these sucking insects will secrete a sticky substance called honeydew that falls onto leaves, furniture and floors. This stickiness is the most obvious sign of scale and the one that most people notice first.

The key to eliminating scale is to treat even the ones that you cannot see. That means thoroughly drenching all leaf and stem surfaces until they are dripping wet. It is also best if you repeat this treatment all over again in 5 to 7 days to catch any crawlers (the translucent young ones) that you missed the first time. After that, you should check your plant weekly to see if they return.

I do not recommend any pesticides because they are all hazardous to use and not 100% effective against scale. The best non-toxic treatment for mealybug and scale is called Brand X Foliage Cleaner. It is available through Southwest Plantscape Products in California (www.southwestplantscape.com). Their phone is 1-800-333-7977.It is a silicon-based product so it is very slippery. Its ability to penetrate is probably the key to its effectiveness because it gets into the tiny crevices that other sprays miss.

You may want to try spraying with rubbing alcohol that will help break through the hard outer barrier of the scale and kill it. Mix 1 part alcohol with 5 parts of water. Add a little liquid soap to help it spread.

Sun Spray Ultra Fine horticultural oil is also mixed with water and effectively smothers the scale. Complete coverage is important.

Another good non-toxic spray is Hot Pepper Wax. Its main ingredient is hot cayenne pepper that overheats the plant pests. There is an information website for it at www.hotpepperwax.com.

Finally neem oil works similarly to horticultural oil. It should be diluted with water and Pine Sol to counteract the onion-like odor. All of these are available nationwide at plant and garden centers and also by mail order.

Important: None of these should be applied to plants in direct sun or in high temps.

Visit my website at  www.HorticulturalHelp.com

If you would like to e-mail me some photos, I may be able to provide some additional insights. Please let me know if any of this is unclear or if you have any additional questions.

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Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

You can E-mail me directly at: [email protected]