Though folks are often intimidated by the thought of tending an orchard, fruit trees don't require any special sort of fertilizer. You can choose between an organic compost, well-dried manure or a commercial mix, which could be any complete fertilizer. You can even mix compost and manure together to create your own custom blend. The most important part of fertilizing pear trees is knowing exactly when to apply the fertilizer, and it isn't as often as you might think.
Mix a small amount of fish emulsion (a few tablespoons) with water and apply every other watering when helping a newly planted pear tree get established. Continue this practice from the planting through the tree's dormancy in winter.
Apply organic compost or well-dried manure to the base of the tree, raking it in to a depth of about 6 inches, if you notice poor growth. Alternately, apply a commercial fertilizer blend designated for fruit trees according to package directions.
Wait for the tree to reap the benefits of the fertilizer and watch for growth and fruiting before applying fertilizer again.
Fertilize only if you notice poor growth on the tree; otherwise, let the tree take care of itself by pulling up nutrients from the soil.