Question
i have a large area of red apple on a slope.  part of it is a nice green and part of it is yellowish to brown in color.  what do i do to the part that is not green--water more, fertilize, or both.  

Answer
Hey, Gary.

The yellow/brown red apple could have one of three problems:

1 - Lack of water
2 - Lack of fertilizer, particularly iron.
3 - No roots.

I've found that here in California, #3 is the most likely, and you're probably wondering how a plant has no roots. Those little critters called gophers like to eat the red apple roots, and when they dig their tunnels in the area, any roots left behind are in their tunnels and not in soil anymore, so then #1 and #2 come into play.

Go out and see if it's easy to pull up a small section of the yellow areas. If it is, no roots. You might also find that the soil kind of sinks in the area when you step on it, indicating underground gopher tunnels.

If everything is okay relating to tunnels and roots, then some localized fertilizer and watering should do the trick.

Hope that helps.

Russel