Q: My indoor Kentia palms have some light brown crusty stuff on them. Is this normal?
A: Midsummer is a good time to check all your indoor plants for problems. Better sunlight and dry air conditioning can stimulate tender new growth that is excellent feed for plant diseases and insects.
As sunlight increases, the likelihood that your plants may need extra fertilization also increases to make sure that the new growth is healthy and vigorous.
It sounds as if your palms have a scale problem. Scale appears on interior plants along the midrib or on the underside of leaves and can grow along the stems and branches of many plants and trees, such as ficus.
Scale looks like little bumps on the plant. They are camouflaged to appear like part of the plant. Scale insects can be especially damaging to new tender growth.
To check for scale, push gently against the bump with your fingernail. The bump should flake off, and you can squash it.
An insecticidal soap such as Safer's can be used to wash the plant thoroughly. Spray it on, and then rub gently with a sponge to wash off the scale. You can also use a gentle dish detergent like Ivory soap.
If your plant is movable, you can take it outside and wash there, and then hose the plant down thoroughly. You can also clean and rinse it in the shower.
Be sure to scrub the surface of the pot, since scale can hide there. Next remove the top inch of the potting soil from the affected plant and replace with a layer of fresh sterile potting soil.
Give your plant a gentle feeding with a liquid plant fertilizer so that new growth will be healthy. Check the stems and midribs of your palm after about 2 weeks for infestation, and then spray with Safer's soap again or repeat the washing.
Scale rarely kills plants unless it is allowed to multiply unchecked. It can weaken the plant, so prompt action is required.
Email Pat Lea at firstname.lastname@example.org.