[Arid_gardener] Buddlea leaves discolored

[billw9 at highstream.net]

We have a buddlea (butterfly bush) which we planted a few months ago.  It is 
doing well and flowering but lately a few of the leaves turn dark brown. 
Part of the leaf may still be green.

It gets watered every other day for about 24 minutes with a 2 GPH dripper. 
It is on the south side of a column at south edge of our patio, so it gets 
sun all day until perhaps 5 pm.

Any ideas to remedy the discoloration?

Bill