Fertilizing for fruit tree longevity?
I received an email from an expert at NAFEX (Bob Purvis) with regard to longevity of fruit trees. He mentioned that the reason he believes fruit trees eventually give out:
"...is partly a matter of exhausting the nutrients in the soil around the roots, probably also a matter of a gradual build-up of soil pathogens. Another thing is that if a tree is unpruned for a long time and allowed to bear heavy crops, the terminal growth gets shorter and shorter each year, and the canopy thinner. This in turn means less photosynthates stored in the roots for the winter. However, regular pruning maintains vigor in a tree if coupled with giving it the water and nutrients it needs. Peach trees are inherently short-lived, but I saw a peach tree in a yard in Yakima, WA that was 31 years old. (That's equivalent to an apple tree 120 years old or a pear that's 250 years old.) The peach tree had been regularly pruned by its owner."
So I am very curious as to how to fertilize fruit trees to promote this longevity. I am assuming that each kind of fruit tree would benefit from different fertilizers.