In general, plants need to be of the same species to be able to cross pollinate. That is kind of the definition of what makes two similar things different species, whether or not they are naturally capable of reproducing together, though there are occasional exceptions.
Apples (Malus) and pears (Pyrus) are not only not the same species, they are not the same genus.
Hi Happy Seedling. Curious about your pear seedlings. What pears were you using as the mother? Growing seedling apples is quite common.....pears not so as far as I know so would be interested as to how you are getting on.
I think they were Bartlett pears. The pear seedlings (x4) are doing very well, given that one is sealed in a jar with no air and some water, and it's alive, and my first to sprout has a leaf bud and three big true leaves, but the third and fourth only have cotyledons so far.
When I wait 3 months for my mango seedling to sprout, and then it damps off.