Q.Avocado sapling has brown tip leaves
I’ve grown an avocado from seed. Recently the end of the leaves have started to crisp up and turn black/brown.
I repotted it but still seems to be getting worse.
Any feedback as to the cause of it would be appreciated.
Certified GKH Gardening Expert
This is very common, and almost unavoidable if this was started using toothpicks and water. This will introduce an infection immediately. Starting seeds this way is really more of a novelty, than lucrative if you wish to obtain fruits one day.
If this was started in soil, then it will have come from oversaturated, and thus infected soil.
What you can do from here is try peroxide. Mix a solution of 1/4 peroxide to 3/4 water. Water this in once your soil is almost completely dry down to two or three inches (if your container has drainage holes), or almost completely dry down to the bottom if you don't have drainage holes.
Wait until this treatment dries as described above and do this again. (It should be about a week in most normal cases between treatments.) After two of these, if the new growth still comes out with brown tips, then do it one last time. This will usually correct it.
If not, you will have to go to a treatment that is safe, but not easy to obtain in your country. DOLOMITIC LIME and WETTABLE SULFUR will be the next option. A handful of DOLOMITIC LIME, and a teaspoon of WETTABLE sulfur (since your container is small) will kill off the fungal infection.
The best way to start these seeds in the future will be direct sowing in soil OR wrapping the seed in a lightly moist papertowel and storing it in a sealed bag in a dark drawer for a week, or up to three.