Answer: I susepct it is an insect. Inspect them very carefully for aphids -- small, soft-bodied insects that suck plant juices. They would be right in the tenderest newest leaves and at the tip of the stem. If you find some, rinse them off with a strong stream of water from the garden hose or spray with insecticidal soap according to the label instructions and covering top and bottom sides of the foliage and the stems. If it's just a few plants, you could also carefully hand pick them off.
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