Umbrella Plant/Arboricola

Question

My plant is losing leaves. The leaves have turned dark brown/black and fall off. The plant is located near a window, pot is large with proper drainage. I feed the plant once a month and water every 10-14 days. During the hot weather my city is experiencing, I spritz the plant. My Marginata is also losing a number of leaves. Both plants are large. I have been closing the blinds more than ususal to keep the sun out.

Answer 1

I would check the roots for root rot. It may be that this fungus has set in and the plant is dying that way. Here is more information on root rot:
https://www.gardeningknowhow.com/plant-problems/disease/treating-root-rot-gardening-tips-for-housplants.htm