Since this may be caused by improper watering, can someone give me some tips on watering?
These plants are on my 2nd floor balcony in Los Angeles and it's been very hot and sunny here for the past month or so, in the 90's most days.
Many of the leaves are drying up and the plants look very bad in addition to having BER, though some parts of the plants look healthy - but other parts look like they're dying because the leaves are drying up.

How much should I be watering them? (They're in big 20" wide by maybe 20" high containers. I know bigger containers would be best but this is what we have.) I have been watering them every morning, giving each one maybe a quart or more of water each day. I figured it was too much but since the leaves are drying maybe it's not enough? I'm terrible at figuring out how much water to give plants! Unless the plant is wilting, then I usually know it needs water - but otherwise, sometimes I get confused...

It was asked "Since this may be caused by improper watering, can someone give me some tips on watering? "

Maintain evenly moist soil or potting mix.

It was asked "If I can use powdered milk, how about pouring regular milk into the dirt..."

The calcium you add now won't be available for a while.

Milk is wasted effort.

As said above, "Maintain evenly moist soil or potting mix." That's the key.

THANKS!!

So am I correct in thinking that using Schultz 10-15-10 plant food daily or every other day was probably what caused this to happen where it had not happened in previous years? Too much nitrogen in that fertilizer?

Plants are not like you, must be feed every day, but more like a snake that must be feed about once a month or so. And, the answer to your Q is: it was a major contributing factor.