How long have you had this tree?
What kind of soil is it in?
How often do you water it?
Where do you normally keep the tree?
How long ago did you start using Daconil?
How long between successive treatments of Daconil?
It does look like a fungus but it also could be a root issue.
I’ve had the tree for a year.
I'm not sure what soil it's in. There's a top and bottom layer of what appears to be perlite or some kind of rock mixture. I've never been able to see what kind of soil lies beneath it, it's a very thick layer.
I got my tree from this seller:
https://dandyfarmer.com/products/zen-the-japanese-elm
You can see from the pictures how the plant is potted and what the top soil looks like (the rocks). My tree is similar to the pictured trees and my pot is identical to the black/dark pot on that page. The pot does seem to retain a lot of moisture for a long time.
I water it when it needs to be watered, or sometimes wait longer and let it dry out a little more. The seller advised me to water it using submersion on a schedule of 5-7 days. But I've learned on these forums how bad that is for the tree so I stopped taking the seller's advice and I'm following the advice from people on here now. I have a toothpick in the soil that I pull out every few days to check and see if it's dry or still wet. If it's dry I'll water the tree from the top until it starts draining out of the bottom. I've been using a liquid fertilizer (bonsai-pro) with every other watering as well for about the past 3 months.
I keep the tree on my west-facing windowsill. Yeah yeah, keep it outside you'll say, I know. I can't. I live in a new york city apartment with no outside access, not even a fire escape, so this is the best I can do for the little tree. On sunny days, it does get about 6 hours of direct light through that window, during late day sun. I also supplement the window light with two grow lights hanging directly above the tree. So it's not all bad - and I also have a humidity meter near the window which consistently reads between 35% - 55% humidity depending on the day, which is not bad for indoors I think.
The first application of daconil was about 4 weeks ago, and re-applied it again last week. I figured it doesn't need to be re-applied as much because the tree is not exposed to the elements? The pictures I posted earlier are from before the first application of daconil.
