Pollination

Pollination is the sexual portion of a tree's life cycle and involves the integration of several biological and physical factors, including cultivar compatibility, synchronous blooming, insects, and proper weather conditions. If any one of these components is missing or limiting, crop yield and quality can be affected.

All apple cultivars require cross-pollination to ensure commercial crops. Varieties differ in their self-fruitfulness. For example, Golden Delicious is considered partially self-fruitful, while Delicious largely is self-unfruitful. Regardless of the degree of self-fruitfulness, provide cross-pollination in every planting.

With respect to cross-pollination, all red sports and spur types are considered the same as the parent variety. For example, Yorking is not a pollinizer for York Imperial. Closely related varieties do not pollinate each other; for example, McIntosh, Early McIntosh, Cortland, and Macoun. Triploid varieties do not pollinate any varieties. Otherwise, all varieties with satisfactory pollen are pollinizers of each other if the bloom periods overlap. It is advisable to have three pollinizer varieties in all Stayman and Winesap blocks.

Cold periods during flowering can reduce pollination and subsequent fruit set. Pollen may fail to germinate when temperatures are below 41°F, and pollen tube growth is extremely slow below 51°F. Therefore, in some situations, temperatures could be warm enough for bees to fly (65°F), but if the weather turns cold the pollen tubes may not grow fast enough before the embryo sac deteriorates.



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