Picking pears is a risky business. If you wait too long the pears might ripen on the tree and then be almost impossible to pick because the fruit will dissolve around the core causing the fruit to be mushy. You have to have the foresight to know when the picking is good to get the best quality fruit. Many amateur pear growers use the thumb method. This is a method I use on my pears and it seems to be okay for the most part. The thumb method is used when you grab your pear and put a fair amount of pressure on the fruit. If there is a small indention in the pear, but the indentation still holds firm, the pear is ready to be picked.
One of the tell tale signs that you may have missed your ultimate opportunity to pick your pears at the right time is when you see that a few pears have ripened and have fallen from the tree. If this is the case, it is time to harvest now. Waiting even a couple of days, especially warm days, you may lose your whole yield.
Another form of evidence that ensures you that it is time to pick your pears is the twisting technique. With this technique, you grab the pear at the base of the stem as close to the fruit as you can. Spin the pear in either a clockwise or counterclockwise direction. If the stem is easily broken and the pear falls free, then it is time to harvest your pears.
Remember different types of pears will ripen at different times. There are many factors of when the pears should be picked. The weather plays an import part in harvesting pears and the length of the day due to latitude is also deciding factor. Bartlett Pears may be ready in early fall in the Northeast, but in the humid Southeast, the pears may still be on the tree well past harvest time and will be mushy in the middle when they are picked too late.
If you do pick your pears a little early, find some place shady to put them to ripen. I have used a root cellar or just the shade from a tree to ripen my pears. You just have to remember to check on your ripening pears often. One day can make the difference between a pear that is so hard it will crack your teeth and a pear that will melt in your mouth with sweet goodness.