Kath says... From Susanna Lyles book - Discovering Fruit and Nuts, page 282
Flowers may be self-infertile, so you may need more than one trees. Insect pollinated: mostly by thrips, which live within the flowers and move onto a new flower once the food reserves have been depleted, inadvertently taking pollen with them. Pollination may be a problem in some locations, although bees will do some. Fruit-set is very variable and many flowers do not develop into fruits.