You never fertilize for "a little browning on leaves". Actually you probably never need to fertilize a normal tree at all, though since this is a fruit tree I guess it would help with that.

As to what to do now... IDK, chop it down? Sounds like a gonner...

what did you do for 3 days.. that involved fertilizer???

ken

Lad, I don't see a "slow trickle" style of watering doing much good in this case if, as I surmise, the fertilizer was broadcast over the entire root zone. If this is the case, get one of those cheap little rotating sprinklers and water the entire area deeply. One of the things you have done with all that fertilizer is caused the tree to dry out. So you need to not only attempt to flush out nitrogen salts from the root sone, but also replace water that was removed from the plant's roots by the presence of all that salty stuff.

+oM

We've had EXTREMELY hot weather in So Cal for the past two months and Avocados got a lot of sunburn in our area. That was probably what happened, and water would have been the right thing, not fertilizer.

I would trickle water again and wait. It may be survive. My neighbor's large Avocado (30') was completely and totally wilted, and it has come back via a couple of deep waterings. Is the area around the roots mulched? They like a cool root area.