I’m having my first case of “something is wrong and I have no idea what it is”. I have a very young Dawn Redwood I’ve been growing for future use. It’s been growing aggressively this spring; by volume, I think it’s doubled in size every month since May.
Around the time of the awful PNW heat wave, it got brown tips on some of the longer needles. I figured this was heat burn, and since the growing tips remained bright green I wasn’t too concerned. But over the past couple days the browning has been spreading. More needle tips have gone tan, and there’s a rusty brown color patching across some of the needles too.
The tree is an an air pot. Currently in regular potting soil. I’ve been fertilizing with high nitrogen granular fertilizer. I haven’t fertilized since I noticed the problem, but there’s some still in the pot. It’s 2 or 3 years old. I’ve been watering about once a day; less when it’s humid since it’s in potting soil. None of my other trees are behaving like this.
I’m consuming as much Dawn Redwood content and Fundamentals content as I have time for, but I’m still very new (first year doing bonsai!) and the problem is progressing faster than I can figure it out. I’d really appreciate any insights!