I have a barlett pear the leaves are healthy and so is the fruit. Hard, crunchy, and white fresh but it taste bitter. Why? should I use a fertilizer or something?
Maybe more info needed for useful suggestion here. How old is tree (if unknown, what is approximate trunk diameter)? When do you pick them? Whether commercially or homegrown, Barlett, or other European pear, is picked and shipped green, but mature. This may be what needs attention. Picked late, they develop grit cells and won't keep long before rotting (often starting in at the core.) Picked too early, they won't have any sugar, and could potentially be bitter. Another question is whether you know for sure it is Bartlett (or perhaps a seedling, which could account for a different flavor) or it just looks similar. For ripenning, I'd usually set a couple pears on the kitchen counter for a few days. If they're still very hard after 4 or 5 days, then they were picked too early. Hope this starts to answer your question.
Should be able to pick 'Bartlett' ripe from the tree. I too wonder if your tree is not really a 'Bartlett' but rather another European pear that requires storage - or is even an inferior seedling rather than a named variety selected for good fruit quality.
Bitter pears typically are known as Perry Pears and have been used for thousands of years to make a pear wine known as Perry. I'd guess your Bartlett died and you have the rootstock which is probably a perry pear. So, celebrate your bitter pears and make wine out of them. :)