http://www.trees-for-you.com/dwarf-fruit-trees.html

Feed your dwarf fruit trees once every two weeks or so in the summer growing season from about May to August with a high-potash food - look for a liquid fertiliser that is specifically blended for flowering and fruiting plants in containers. Pears don't seem to respond to inorganic fertilisers, so use an organic one.

What the heck? Why would this be?