Help! Massive leaf loss in 10 ft Alii Ficus
A month ago, I bought a 10 ft tall huge beautiful ficus alii from pike. Since the day it came home, its been steadily losing leaves. I have another much smaller ficus alii that I've had for 6 months and its never lost leaves. I put the new tree right next to my old one, in my sunroom where it gets bright indirect light. The leaf loss was mostly seen as leaves that had brown streaks coming from the center vein. Leaves on the trees also developed dry brown tips but those doesn't fall off.
I read that streaks from the center vein mean too much water and that the cells are essentially rupturing. However, I read that brown tips are a drought response. I watered once a week but every time I watered (room temp water) I noticed the next day there were tons of new dropped leaves, mostly with brown streaks.
Three days ago, I pulled the tree from the pot and saw that the entire root ball was basically one giant white mold colony. I spent an hour washing the very compact and paper-like soil away from the very very dense roots. I had to take a knife and make some vertical cuts through the root ball to get to the center. There was mold growth all the way through! I repotted with a 30% pine bark, 30% soil conditioner (ingredients say >90% tree bark, looks almost identical to the pine bark), 40% perlite soil mix. I mixed in a handful of Osmocote all purpose plant food pellets. Watered until water ran out the bottom, and put the tree back in its spot in the sunroom.
The next day, I only noticed one leaf on the ground! I thought I had solved my problem. However, its not three days later and the leaf drop rate is back to what it was before. The dead leaf appearance has changed though. Before, it was mostly large mature leaves that dropped. Now, its a 50/50 mix of big leaves and smaller leaves. Also, some leaves show the same brown streaking from the center, but now there are leaves with brown streaking on the edges.
My original, smaller, ficus alii is right next to this tree and still doing great. For that tree, I just transplanted the whole root ball into a larger pot and filled in with miracle grow moisture control potting soil.
What can I do? This large tree was $400 and I don't want to lose it. Aside from the price, its literally my dream tree and its very special to me and the centerpiece of my sunroom! Including the pot, it almost touches the 12 ft ceiling!
Attached is a pic of dropped leaves and how the tree looks. You can't tell, but its already dropped half its leaves. Note some are crinkled while others drop in their healthy shape.