I had no intention of growing an avocado tree, but some months back, I cut open an avocado and found the pit cracked and a little root inside. I didn’t have the heart to throw it away, so I put it in a glass of water, and then, at the appropriate stage of development, into a pot, where it’s been happily growing ever since. It’s rather surprising, since I live in cloudy western Washington.
About 3 weeks ago, I noticed a leaf turning black around the edges. The black spread inward, and I pulled the leaf. Now the other leaves are doing the same. Here’s the sickest leaf, and here’s one that’s just starting to turn.
What the heck is going on? A fungal infection? It’s been in the same pot with the same soil (Miracle Gro, fresh from a new bag) and the same (city) water it’s had all along. I have not fed it. The pot does have a water catcher at the bottom. Maybe I didn’t get all the water out, and some microbe or fungus or something traveled into the soil? It’s a big pot, much bigger than the root system.
It’s been such a determined little plant, I hate to just let it go if there’s a good chance to save it. I’d appreciate any diagnosis and/or suggestions.
It looks like a cultural problem rather than a pest issue.
If there’s been a saucer under the pot collecting water, too much dampness could be the problem. Does the pot feel heavy? If you unpot the plant is the lower soil medium soggy?
If that’s the case you can remove excess wet soil, trim away any rotted/black roots and repot in a smaller container (overly large ones contribute to persistent dampness since there isn’t enough root mass to take up all the moisture).
Another reason for leaf edge browning is low humidity, but if the plant has been doing well all along it’s less likely to be the problem.
I sincerely hope that your hardy little avocado isn’t toast.
I’m sympathetic. I grew one for a few years and it was a beautiful plant. It actually lived at work in front of a window and everyone complemented this young tree. About two feet tall from the soil surface with plenty of pretty leaves symmetrical all around.
One day, it began to drop leaves. They were all gone within a couple months. I don’t know what happened. I stuck with the same watering and fertilizer routine from when it was thriving. I continued to water it until the trunk shriveled which took another few months.
Sorry can’t help you myself, but have you done a Google search “diagnose my sick avocado plant” ?
Lots of helpful information available:-
https://www.google.com/search?q=diagnose+my+sick+avocado+plant&oq=diagnose+my+sick+avocado+plant&ie=UTF-8
Good luck 
Yes, of course. I did that before I turned to the ever-helpful Dope. Many of the sites dealt with full-grown trees. Others were helpful in ruling out possible causes like pests or many fungal infections but didn’t address black leaves.
I think this might be it. The pot feels heavy because it’s a big frickin’ pot. I foolishly thought, “Hey, this thing’s going to become a tree. Why transplant twice?” So I think you’re spot on. I’m going to un-pot it and check out the roots tomorrow. I don’t have a smaller pot that isn’t tiny so will have to walk to a store and buy one. Thanks so much for the help!
I laughed way too hard at this.
I’m sorry. Despite myself, I’ve grown attached to mine and have complete empathy.
My mom began growing a few avocados after my apparent success. I messaged her last night and hers have been growing over 10 years but she reported that the oldest one doesn’t look so hot this spring. She always summers them outside which I never did, maybe that’s important?
[Moderating]
“Let me Google that for you” responses are not appropriate for FQ. We all already know that Google exists. If you want to use Google to be helpful, then use it to find the answer, and then either link to or paraphrase that.
Last night I saw the opening of the movie “Red”, which shows the avocado plant of Frank Moses. I diagnosed Hollywood fakery, since the leaves seen emerging from the avocado pit were not avocado leaves.