I bought this dwarf avocado (Wurtz) tree this spring. I potted it and left it on the deck for the summer, where it thrived. It probably added 10" of growth. Brought it inside just before the first frost.

I misted it every day, and had only watered it once since bringing it in. I kept checking the soil, and the soil didn't seem to be drying out at all. Today marked about 9 weeks since I last watered it, and the soil is just now dry to the touch.

The leaves started browning and falling off. I thought it was just adjusting to the lower light levels, but they kept dropping, until it hit it's current state: most of the leaves are gone. The few that remain are browning. The exception is at the top, where I appear to have some new healthy growth.

I also began to notice a few fungus gnats, so I expected the worst: root rot. However, today, I unpotted it and inspected the roots: there were no brown or rotted roots, and the soil smelled fine. I repotted it after drilling some more drainage holes in the container (using fresh soil).

So I'm a bit stumped on what this could be. Here is what I *think* I've eliminated:
1) Root rot- no visible signs
2) Salt buildup- only watered 5-6 times TOTAL since getting it, as rain took care of that
3) Insufficient water
4) Insufficient nutrients- mixed a citrus/avocado fertilizer in with the soil when I repotted it

My only other guess is that while it wasn't bad enough to rot the roots, the plant didn't like having wet feet for so long. I would appreciate any thoughts or feedback.