White "decay" on Catlin Elm

[Ryan Cheng]

If anyone knows, would lemon juice (diluted in water) be just a good a substitute for vinegar to treat hard water stains?

P.S. Still would like to know if I should remove the whole leaf or only the affected area of the leaf (i.e. cut the leaf in half).

 

[0soyoung]

P.S. Still would like to know if I should remove the whole leaf or only the affected area of the leaf (i.e. cut the leaf in half).

It doesn't matter. On the outside of the leaf it is purely cosmetic.