What's the problem here?

[Shufigo]

Here's a pic of some Ayers pears off a graft onto a native deer pear tree. Most of the other pears on this year's grafts are normal. I do, however, have about 20 with this cracking appearance. Can anyone help on ID'ing the problem - and how to avoid it in the future? Thanks for any help you can give.

 

[Native Hunter]

I've never seen it myself, but below is probably your answer. There is also a disease called pear scab that can cause fruit to crack:
Why Fruit Skins Split - Advice from Ashridge Nurseries (ashridgetrees.co.uk)

 

[Mennoniteman]

Did you have a very wet week as the fruit was maturing? This was a common condition with my dad's cherry orchard, the fastest growing, softer varieties were more susceptible, and the split usually heals a skin over it and isn't an open wound, so they are still edible, and it didn't affect the flavor, in fact, the split ones often have the best flavor.