Answer: The white patches could be powdery mildew fungus, or mealybugs. Try washing the patches off. If they stick around, they're probably mealybugs. These insect pests attach themselves to stems and leaves and feed on the fluids within plant tissues. Spraying weekly with insecticidal soap will deter these pests. You should be able to purchase insecticidal soap at your local garden center. You can also try spraying with a soapy water mixture. Or, try dabbing them with rubbing alcohol. Keep a very close eye on your other houseplants, as all these pests spread easily.
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