Avocado brown leaves

HI,

I have searched and searched on the internet and cannot find what seems like something obviously wrong with one of my two avocados. The one just up the slope a few feet has a nice crop on it right now with just a very small amount of some brown leaf tips.

The one below it which has not looked good since we moved in over a year ago has A LOT of brown leave margins. At first when we started watering and fertilizing it (cow manure), the new growth really perked up and it looked great. But, it just has not improved. It looks like it has flowers emerging now though. I am attaching two photos.

Please tell me what could be causing this and what I can do to solve it, if possible.

Thanks so much!

EDITORS NOTE - PLEASE SEE PHOTO BELOW

Here's the photo for Sierra:)

Hi Sierra,
My Avocado looks exactly like that every year about this time. Last year I took a leaf down to Walter Andersen Nursery and they said I had two problems, a bug that causes little brown spots on the back of the leaf and Salt in the soil which causes the tips of the leaf to turn brown. It seems that the water we use around here (I'm in San Diego Too) has a lot of salt and that over time it builds up in the soil. There suggestion was to give a really good deep watering once or twice a year, this releases the salt accumulation in the soil and it's released deeper into the soil where it won't cause trouble for your Tree. It's tough to do because of the water restrictions, but it seems to work (if I remember to do it). If I forget to do it seems like the tree takes care of itself, as the old brown leaves eventually fall off and the new growth takes over. This good clean wonderful rain we've been getting is doing the same thing for us right now:laugh:
The cow manure probably doesn't help at all, I think it has a lot of salt in it too...

About the spots on the back of the leaf, I'm not sure you have that same problem (i couldn't tell absolutely) but it looked like you may. - oops I have to go, i'll get the rest later today.