Q.bad tasting lemons
I have a very large lemon tree in my back yard that is about 10 years old. My mom bought it for me from a farmer’s market. It produces large lemons every year, about the size of a grapefruit. They smell great like lemons should smell, but they taste awful! We can’t use them for anything! Is there anything I can do other than chop it down?
What kind of lemon tree is it? How much water and fertilizer has it received? Is the tree showing any signs of stress such as yellowing leaves or fungal problems?
Has the tree never produced good tasting fruit? Since the tree has apparently been this way for a decade it could have been a problem with the rootstock - it may have taken over the crown. I think this may be the case due to the shape of your lemons. The variety of root stock for most citrus is "Sour Orange" which is very bitter, but it has the shape of a large orange, not a Lemon.
Barring that, it could also be the timing of harvest. Lemons that are harvested too soon will be overly sour. Those that are harvested too late will be overripe with little taste.
For more information on growing lemon trees, please visit the following link:
https://www.gardeningknowhow.com/edible/fruits/lemons/how-to-grow-a-lemon-tree.htm