It is normal for MOST of the tiny fruit to fall soon after blossom, but you should have some set and stay on. I am a huge believer in mulch for fruit trees, especially shallow rooted ones like citrus and Avo's. It keeps soil temp cool, acts as a buffer for water so the soil doesn't have such big swings of too wet to dry between waterings, it feeds the full spectrum of nutrients as it decomposes, it helps healthy soil horizons develop, just to name a few of the best reasons. All of these things help the tree grow healthy and strong and so better able to carry good fruit. Put about 6 inches of mulch under the tree and extending out 2 feet past the drip line. Pull back a little away from the trunk fro several inches, so you don't get rot at the base. Water it down so that it will stay in place. Add more each year so that you always have at least 2 to 3 inches covering the soil. Remember mulch is a slow process, just like trees are slower than squash, so mulch is slower than chemical fertilizer. You won't mulch on Monday and see this huge bunch of fruit this weekend. But a good mulch builds a good soil that supports a good tree. You will see real results over the next few months and I would guess good fruit next season. One last thought, there are A and B flower Avo's. One of each is not needed for pollination but it helps. Still, in LA there are lots of Avo's in lots of yards, so there may be other trees close enough to help with pollen.

Looks like significant stem damage on the last picture. Return it and get another. Do not expect them to do any growing until it warms up in spring. Baby avocado trees won't grow at this time of year (unless you are in southern Mexico). They grow when it is warm. Mulch the area around the base with a thick (4-6") mulch, keeping the area immediately around the base of the trunk clear. The root systems are sensitive and like protection.

I've been trying for years to help my parents in Walnut Creek, CA grow avocados bc we see and know of nearby trees, including a friend's tree that survived the all time record freeze of 1990, and they've lost several trees, always during the summer, due to these same issues of leaf browning, blackening and shriveling of stems and trunk, etc. They grow sapote, guava, and macadamia in the same part of the yard, but those darn avos won't make it. With low watering, high summer heatwaves, and clay soil, it sounds like we're getting to the bottom of things. If I can persuade them to try another Mexicola Grande, then with more water and lots of gypsum, maybe theyll have better luck. Thanks for the tips!

The color on the leaves is from spider mites damage ( tiny insects sucking the life out of the leaves), spray the plant and leaves thoroughly, underside of the leaves as well with water and then spray again everything including the soil with horticultural oil spray. The brown spots are from too much water. Remove the stake, let the tree stand on it's own to get stronger.