What is the plant growing in? The ground? A container?
If the latter, what did you fill the container with?
And how do you decide it's time to water?

The cupping and edge yellowing followed by necrosis is very similar to boron deficiency, but I am extremely hesitant to advise any boron adjustment unless you know the base value of your boron content to begin with.

It is both very easy and very detrimental to plants to over-apply boron and it should only be done with a soil test.