Q: My basil plants have brown bumps on the lower part of their stems, and my diagnostic app said they could be scale. A: Apps vary in how accurate they are for any given diagnosis, and the more likely explanation in this case is that the bumps are adventitious roots. Adventitious roots do not typically finish developing into fully-fledged roots, and instead remain as firm, brownish or pale green nubs clustered on the stem. If the bumps on your basil stem do not rub off easily and are not associated with honeydew (a sticky, clear residue), then scale insects are not likely. In comparison, adventitious roots will not come off unless you scrape them away, which will injure the stem in the process.
