One of my jade plants has some sort of white fluff on the stems. Is this normal?
White fluff is not normal. Your jade plant is no doubt hosting an infestation of mealybugs, tiny sap-sucking insects that will damage the plants if they are left to multiply. They appear as small, cottony growths on the stems and leaves of jade plants and many other houseplants. They do their damage by inserting their piercing mouthparts into the plant’s tissue and extracting the juices.
Mealybugs thrive in a warm, dry environment – such as inside a home in winter. Female mealybugs don’t fly, but once established on a plant, they can find their way to nearby houseplants so it’s good to get rid of them as quickly as you can – not always an easy task, because that fluff is rather waxy and resistant to pesticides.
The best way to begin to eradicate the insects is to remove them by hand. Dip a cotton swab in rubbing alcohol and wipe them off. You may have to do this two or three times until all the unseen eggs that may have been deposited have hatched. If the infestation is heavier, follow up with a spray of insecticidal soap.
Always be watchful for insects to reappear, and try to get rid of them quickly. In addition to jade plants, mealybugs may find their way onto African violets, ferns, pothos, Norfolk Island pine, schefflera, diffenbachia, pothos, philodendron and many other popular houseplants.
Mealybugs are a common problem, and information is readily available. The North Carolina State University Cooperative Extension provides information here.