In flowers, pollination is the transfer of pollen from the anther to the stigma. After pollination and fertilization, fruit set occurs. There are two types of pollination. Self-pollination occurs when the pollen is transferred from the anther to the stigma on the same flower, from another flower on the same plant, or from a flower on another plant of the same cultivar. Self-pollinated plants are said to be self-fruitful. Many plants cannot produce fruit from their own pollen and are considered self-unfruitful. These plants require cross-pollination for fruit set. Cross-pollination is the transfer of pollen from one plant to the flower of a genetically different plant or cultivar. Pollination is an important factor when selecting and planting tree fruits. A list of pollination requirements for the various tree fruits is presented below.
Fruit trees that require two different cultivars for pollination should be planted within 50 to 100 feet of one another to insure good fruit set.
Apples are regarded as self-unfruitful. Most apple cultivars will set a small crop with their own pollen. However, for maximum production, plant at least two different cultivars with overlapping bloom periods to insure cross-pollination and fruit set. Apple cultivars can be classified as early, mid, and late season blooming. The bloom periods of early and mid-season bloomers overlap, allowing for ample cross-pollination and fruit set. Good pollination can also be expected with mid and late blooming cultivars. However, the bloom periods of early and late blooming cultivars may not overlap, resulting in poor pollination. The bloom periods of commonly grown apple cultivars in Iowa can be found in PM-453 Fruit Cultivars for Iowa.
Few apricot cultivars are reliably cold hardy in Iowa. ‘Moongold’ and ‘Sungold’ are hardy throughout Iowa and self-unfruitful. Plant at least one of each for proper pollination. ‘Moorpark’ can be successfully grown in central and southern Iowa. ‘Moorpark’ is self-fruitful.
Sour or pie cherries are self-fruitful.
Most sweet cherries are not reliably cold hardy in Iowa. Most cultivars are self-unfruitful. ‘Gold,’ BlackGold™, and WhiteGold™ can be successfully grown in central and southern Iowa. ‘Gold’ is self-unfruitful. BlackGold™ and WhiteGold™ are self-fruitful. (BlackGold™ will pollinate ‘Gold.’)
Peaches are not reliably cold hardy in much of Iowa. ‘Reliance’ (yellow flesh, freestone), ‘Contender’ (yellow flesh, freestone), and ‘Polly’ (white flesh, clingstone) are most successfully grown in the southern one-third of Iowa. Most peach cultivars are self-fruitful.
Most European pears are self-unfruitful. Plant at least 2 different cultivars for maximum fruit production. Asian pear cultivars are partially self-fruitful, best yields are obtained when two or more cultivars are planted together. Most Asian pears are not as cold hardy as European pears. Asian pears perform best in the southern half of Iowa.
Japanese plums are not reliably cold hardy in Iowa. However, European and hybrid plums can be successfully grown in the state. European plums are partially to entirely self-fruitful. Hybrid plum cultivars (crosses between American and Japanese plums) are self-unfruitful. Plant 2 or more hybrid plum cultivars to insure cross-pollination and fruit set. European plums will not pollinate hybrid plums and vice versa.
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