Scales on seedlings

Asked April 30, 2020, 11:35 AM EDT

I started various plants from seeds under grow lights - ricin, datura, tomatoes, etc. I now find some of them have little round insects on the stem with a sticky substance. I assume they are scale. Now idea where it could have come from. Could it have been in the Miracle Grow Moisture potting soil from Sam's Club? Now, how can I get rid of these critters without killing the seedlings?

St. Louis County Minnesota

1 Response

The sticky substance is honeydew, so you are probably describing scale, mealybugs or aphids. I doubt they came from infested potting soil. More likely they are around your home - they are attracted to any plant material. They could have been on any container you used (if you didn't clean it with bleach). Your plant growing environment was probably ideal for them. It is important to check plants regularly for scale, aphids and other problems so you can treat before they become serious.

As for treatment, this is tricky. Normally, insecticidal soap or horticultural oil is effective, but too much can set back the plant dramatically. You might start by simply trying to wash the scale off. If that fails, try insecticidal soap. Read here:
https://extension.umn.edu/product-and-houseplant-pests/insects-indoor-plants

And, btw, I hope you know that ricin and datura are both very poisonous.