Question
I grew this tree from a seed, and it's now (I think) 7 years old.  It nearly died the 2nd year because my patio in washington DC gets unbearably hot in the middle of summer.  Since then I have been bringing it in in both summer and winter.  2 years ago, I left it out too long in the fall, and it died in a frost--or so I thought.  After almost a year of dormancy (yes, I was lazy) it resprouted, and is now again a little over 3' tall and starting to grow branches. It has a really fascinating root ball due to its many incarnations.  HOWEVER, I see scales on the undersides of the leaves.  I have had bad luck in the past removing scales from plants, but I really don't want to have to throw this one out.  The infestation isn't bad right now.

I am concerned that it's living in recycled soil and the soil should be replaced (last time it was replaced was over 3 years ago.)  However, I do not want to damage the root ball by removing too much, so how much is this necessary to avoid the scale infestation?  Do you have any suggestions for me?

Answer
Hi Deb,

The scale insect infestation is not related to the soil. The scales do not live in the soil.

To teat the scale, mix a solution of 5 parts water, 1 part rubbing alcohol and a squirt of liquid dish soap. Take your tree outside on a cloudy or overcast day and spray the entire tree until all leaf and stem surfaces are dripping wet. The spray must make direct contact with every scale insect, even the ones that are virtually invisible. That is why complete coverage is necessary although messy. After spraying, you can wipe away the visible scales. Move it back inside as soon as the dripping has stopped. Protect it from any direct sun while it is wet with spray.

If you are really thorough, one treatment is usually adequate.

Although I don't recommend using recycled potting soil, I also do not recommend ever replacing soil. To do so will damage most of the tiny roothairs that do most of the work. So leave the soil alone. If you think the soil is depleted of nutrients, then use a standard fertilizer diluted to half strength and applied monthly.

I have written articles on treating plant pests that I will email for free to you (or anyone else) who emails a request to me at [email protected].

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

Visit my website at: A link to HorticulturalHelp.com