If the pollen has to come from a different variety for pollination to occur the process is called self-unfruitful . Therefore two varieties have to be planted for fruit set to occur. This is called cross-pollination . The following is a pollination guide for various fruit trees grown in Arizona. As a rule self unfruitful and need two varieties to ensure good fruit set, Red Delicious and uts strains need a pollenizer.
Golden delicious is a good pollenizer.
Rome strains, Yellow Transparent, and Grimes Golden are usually self-fruitful. Winesap and Stayman winesap have sterile pollen. Crab apples that bloom at the same time as apple can be used as pollenizers. Always need two varieties to ensure good fruit set. Variety Seckel is not a good pollenizer.