repot it... you won't have any issues. I repot trees all summer long from small to big pots...most are completely rootbound... have never noticed any issues (they usually respond with growth)...just water good/fertilize and be done.

Depends where your friend is trying to grow these. If he is near the coast they need full sun in order to ripen. If he's inland, they should be able to tolerate some shade. Also, what do you mean by "not ripen"? Do they fall off before getting ripe? could be frost and cold stress that is causing that. The banana problem is slightly different, if your friend doesn't cut off pups and focus all the energy into the fruiting corm, and doesn't fertilize, the fruit will stay small.

It can be brown rot, but I'm not sure. The way you can be sure you have brown rot is some of the peaches in an advanced stage will have the brown dull powdery stuff on the outside. If that is what you have you need to spray, primarily in the early phases of fruit formation, to prevent the disease, and also perhaps a spray in July just before fruits start ripening. I use Serenade, an organic product, and it seems to work OK. You can also use propiconazole (Monterey Garden Fungi-Fighter). The peaches rotting in the bag are probably rotting due to brown rot, so it does sound like the fungus is present. The only thing about your description that doesn't quite add up is the way the fruits are falling off before they ripen. When you have brown rot they usually don't drop early, and in fact they can "mummify" on the tree, turning all shriveled and gross. Also it sounds like the fruits falling off look fine, just hard and unripe. It makes me wonder a bit if a storm or hail or something didn't come through and blow them off. One last thing it could be is some varieties of peach can drop fruits when they are young trees. It is common for them to drop in June but is not common to drop so late. Overall, I would spray for brown rot next year and hope for better luck.. Scott

Maybe this particular tree just isn't 'ready' yet. Here is a link with a limited discussion on fruit drop. It's a good site though Here is a link that might be useful: Fruit Drop