Munalos: To the best of my knowledge, apple pollen will not set fruit on pear and the other way around won't work either. If they did, you would have a cross. Having said that, they have crossed other fruits like peach, apricot, and plum to give hybrids of those fruit. But if you are wondering if an apple will pollinate your pear, no, don't expect that.

The Fruitnut

Not long ago both apple and pear were classified in the same same genus.

I was not asking if they would set seed but, I was wondering if they would set fruit.

Triploids will set fruit but are generaly sterile.

I did not know if something like that may happen with the appels and pears.
thank you
Munalos

Munalos: No they won't set fruit on each other.

I would like to say that while apple and pear are not used commercially to pollinize each other, it is not impossible for them to use each others pollen. I have in my collection an actual Red Delicious crossed with a pear. It is a part of a certain research project I am conducting.

I'd love to hear more about your research plumfan.