I agree with Ed that this is most likely to be a cottony mealybug.
- You can control this taking a paper towel soaked in dish soap and water and wiping the leaves down.
- Repeat for every leaf with the symptoms. Check the axils where the leaves join the stems too.
- After the treatment rinse or spray with water to prevent a soapy buildup
- repeat every five to seven days for at least three times
- continue to monitor as mealybug is hard to get rid of
- move the tree away from any other houseplants. Some adult mealybugs have wings and fly to spread the population.
- check for other plants that may have it too