Stephie could be right...what I see as your main problem from your photograph is POWDERY MILDEW. All those whitish blobs across veins. Very common on a lot of different species of plants and easy to control/treat.
You need more ventilation/aeration and lower humidity. Free water on the leaves is helpful. Continuously damp soil and little air movement provides ideal environment for this fungus. Powdery mildew is not good for plants!
A mix of 1 part milk to 9 parts water sprayed once per week regularly helps tremendously. I just learned this from 'Bamboo' last summer off this site. Neem works very well. Just read the label very closely and spray in isolation from bees and birds and pets.
Fix the problem. Get a little fan to keep air moving and allow the soil to dry out between waterings. Pay attention to this trunk! Get all gravel, moss pulled away from the base. Make SURE that the bark of the upright trunk is never covered. Moisture on the bark will allow bacteria to kill the cambium just beneath the bark. This is the vital vascular conduit system to transport food produced by the plant down to the roots and minerals/chemicals/water conduits upward to support the food making factories in the leaves. Find the fine line where bark stops and roots begin. Keep the bark dry! All woody plants indoors as well as outdoors need this care.
After soaking your plant, allowing it to drain (try not to use our tap water unless on private wells), keep the saucer emptied...allow to dry before watering again. Never water a little everyday. Place this plant in your tub and water with non-softened water. Soak this plant and wash off leaves. Again, allow soil to dry before watering again.
Your problem is too much humidity. Your plant is still very healthy if bark has no soft spots. What are you doing for adding important nutrient/chemicals back to soil? Fertilizers? What are the lighting conditions? Might not need a fan if you reduce waterings...only fill your pots for plants with sterilized potting soil. Never garden soil. And gravel/rocks below the soil only worsen drainage!!!!