OMG thank you so much for such a detailed reply.

I have only had it for two months. Didn't fertilize it yet. I mean I did when planted it back in September. And it is in the ground, yes. We live on the hills in LA. So I admit the soil is difficult. It doesn't drain well, but I kept close eye on its drainage. And I do water religiously. Now, about the light :). The very second day I could see the leaves totally wilted on the sun. Since then every time the temp was going higher than 30°C (90F), I put the screen to cut half of the sunlight. It seemed to be working well this way until a couple of weeks ago suddenly the temperature went all they way to 100!! In three days leaves dried out and started just falling off! And I couldn't help it.

So you're having the complete opposite problem with lighting. It seems like your tree is drying out or getting leaf sunscald, which is basically leaf sunburning. Did the leaves turn white before falling off your tree? Or it could be the temperatures.

I think it may be getting too hot where you live - they do better in coastal areas where the temperature rarely goes above 90°. Mine loses leaves seasonally, but never all at once. I'm growing mine in a whiskey barrel planter, since my soil does not drain well, and I give it full sun. I've gotten fruit each year for the past three years, and the tree made fruit the second year that I had it, although never very much.

Here'ssome more info on growing them. They recommend 8-8-8 fertilizer. If mine gets rootbound (which so far it has not), I will plant it in the ground.

It went from growers light shade cloth..to hot L.A. sun. Now,just water it heavy and MULCH it. It should recover now that winters low sun is here with full sun foliage.

The more sun- the more water they need. You are not too hot for them,just too dry..for now.

Thank you so much for your replies!!! I am going to do that. I'll try to move it also, so it'll stay in a shadier spot... Hopefully it'll recover.

The link is so helpful! thank you, Lars(Z11a, Sunset 24)!

It's a "tropical mountain" plant.....it needs warm, not hot climate....half day of direct sun is often enough. Ideally, in not tropical region with very hot summer, should be to plant it in a position where it gets shadow (for half day) from decidoduous tree, so during winter will be in full sun.

Sometimes A. cherymoya loses its leaves, usually before flowering...so you should wait to understand if its physiological or not.