Brown spots on houseplant and avocado leaves.
Two viewers have similar issues on two different plants, both grown in containers. Eloise Hunt’s Dracaena has developed yellow leaf margins that eventually turn brown, and the edges of Anita Shekar’s avocado leaves are turning brown.
Although the symptoms look slightly different, both plants are suffering from the same problem: a buildup of salt in the leaves, which leads to marginal tip burn.
To understand this, think about the way your tongue feels when you’ve eaten lots of popcorn with too much salt. It feels kind of raw and burns a little. Well, leaves are just as sensitive to salt, so when they take up water that contains too much salt, then the water evaporates from their leaves and the salt is left behind, the tissues get burned, turn yellow or brown, then die.
Some plants are more sensitive to salt than others, and container-grown plants will struggle more than those in the ground, since they’re growing in a finite amount of potting soil, where salt builds up more easily.
Although you likely won’t be able to get this issue totally under control, there are a few things you can do to keep it at bay.
First, soak the container in a basin of water for a few hours, so that the potting soil can fully and uniformly rehydrate. Upon subsequent waterings, you should flush the container very well, making sure that lots of water passes all the way through and out the bottom.
You could also switch to using bottled water or rainwater for these plants. With the avocado, the plant looks overall very healthy to me.
Try to get the watering more uniform and work on protecting the plant from heat: tender new leaves are especially vulnerable to heat, wind, and salinity.
And take heart: according to our AgriLife Extension fruit specialists, the most common problem with avocados in Texas is tip burn and marginal necrosis, caused by water stress and salinity.