What’s the problem of this besseae leaf?

[Daniel2]

An old leaf of a besseae. Several new leaves have the same symptom. Wish to know the cause and how to treat?

 

[Cheyenne]

In my experience my besseae look like this if I don't use very good quality water or they still have fertilizer in there mix when they dry out a little. Use rain water or RO water and flush good a few days after you fertilize. I thought I was using good water but after going to rain water for them they are looking good again.

 

[Shiva]

besseae are not easy to grow well sometimes. Like Cheyenne says, they need rain or ro water, and very little fertiliser. Your's is not so bad...yet!