Question
We have a large Schefflera, not sure what kind it actually is, it is somewhere around 6 to 7 feet tall and we keep it in the dining room and it gets plenty of sunlight.  It is growing great but we have been noticing a problem with sticky leaves and sticky floor under the leaves.  We was told that this might be some kind of disease but I have not been able to find any articles that have said anything about sticky leaves.  We have looked extremely close at the plant and can not find any kind of bugs on it and have had no browning of the leaves or anything.  Do you know anything about what could be causing this, is it something we should really be worried about and if it is what should we do about it?

Answer
Hi Jake,

Your Schefflera is probably a Schefflera actinophylla.

The stickiness is caused by either scale insects or mealybugs, probably the former. Mealybugs look like tiny bits of white cotton and are more noticeable than scale insects. Let me tell you about scale so you will better understand them and how to treat them.

Scale can be hard to detect. They resemble insects when they are babies, but they are smaller than a pinhead and very hard to see. When they find a suitable site, they insert their tiny probes into the plant tissue and stay there. As adults, these sucking insects are slightly oval, slightly raised, translucent bumps or blisters 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.

Soap sprays are not as effective as some other treatments because soap doesn't always penetrate the hard outer shell of the scale.

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 8 to 10 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.

Please let me know if any of this is unclear or if you have any additional questions.

Regards,
Will Creed, Interior Landscaper
Horticultural Help, NYC

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

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