When that happens around here the general consensus is that the tree needs to be fertilized. It seems that if the tree is not getting enough nutrients it will start dropping fruit. My young trees dropped their fruit last year and the year before. This year I fertilized them in late spring. They began dropping fruit. I fertilized them. They stopped dropping fruit and are now holding them.

I did fertilize in the spring.. maybe not enough. could squirrels be a factor?

That is a possibility. Rats are known to climb the avo trees to get to the fruit. I do not know about "tree rats" though. Are you finding aborted fruit on the ground under the tree? Or, are they disappearing completely? I've noted that the trees will set many more fruit than they will end up carrying to maturity. Whether that is normal or a condition, I do not know.

they are on the ground under the tree. thanks for your input

It's normal for trees to set many more fruit than they can carry to maturity. My tree often sets six to eight on a single inflorescence, but it will only keep one or (rarely) two. Based on the photo, your tree's fruit look pretty mature, though small. Have you taken any inside and tried to ripen them? Don't assume that because the mother tree had large fruit, your tree's fruit will be the same, or even similar. The only sure way to get the same fruit is by cloning--typically by grafting. Planting a seed may yield a tree with excellent fruit, or it may not--it's simply a roll of the genetic dice.

thank you for your input.. However, at this point, all the fruit has fallen off the tree. I did try to bring some in to ripen, but didnt work. After further review of the fruit, it seems that the stem area on fruit is hollowed out, if that makes sense. The tree is very tall. (not sure what you consider small). just cant believe that a tree that had hundreds of avocados, now has nothing.. so disappointed.

That's too bad. Sometimes a tree will drop all or most of its fruit the first year is sets any, but your tree is clearly large enough to support a good crop, so I don't have much to suggest. You could try waiting another year or two, but if the same thing keeps happening, it will be a good indication that your tree is just another losing entry in the "seedling lottery." If you want good avocados, you'll probably have to buy a good grafted variety from a nursery.

Two issues I think:

#1 If i understand correct, it is from seed. So the variety is a bastard. They may be a small variety at maturity.

#2 if they are falling off at grape size or smaller, it is a pollination issue at the peak flowering time. Be it a cold snap or some other stress to tree or insect, the flowers did not pollinate. Hence early fruit drop.

yes its from seed.. the fruit to which it came from was a regular sized avocado, if that makes sense. #2 some of the fruit was grape size, but some got bigger (2 1/2-3" long), then fell off. All I can hope for now, is that next year will be better.

Shellroc, The seed is not true to the parent tree. So you basiclly have a rootstock of an unknown avo variety. They may only get 3" long. But if this is the first year of fruit production, I would expect the next 2-3 years to improve on this one. But again, being a seed start, you never know. I hope for the best.