Question
Hi Will,
Is it possible for scales to infect ivy's and spider plants? I have 5 plants that are infected now (2 rubber plants, poinsetta, and two I don't know what they are). I have given them a mild soap bath with warm water followed by applying rubbing alcohol to each scale. How do I know when the scales are dead? Does moisture activate the scales? I also have about 10-12 spiders and ivy's that I don't want to get infected but isolation is tough due to limited room, or more appropiately, excessive plants.
Thanks,
Julie

Answer
Hi Julie,

I'm glad you found me because I can help!

Yes, scale insects like Hedera ivies and spider plants. Look on the underside of the leaves for early signs of these critters.

I know that quarantine is usually recommended, but I know that is both impractical and unnecessary if you follow a good treatment plan.

SCALE INSECTS CANNOT BE TREATED ONE-BY-ONE. This is where most treatment plans go wrong. Dabbing each scale with a Q-tip is not only tedious and time consuming, it is not effective.

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. (Moisture does not activate or deactivate these critters.)

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.

If you are thorough with your spray coverage, then you can be reasonably sure that they will all be dead within 24 hours. They may not look dead, but you should be able to wipe them off the leaves with little effort.

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]

Visit my web site at www.HorticulturalHelp.com