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Pollination

In order for fruit to develop, pollination must occur at blossom time. Pollination is the transfer of pollen from the male part of the flower to the female part of the flower. Some types of fruit trees may be pollinated with their own pollen and are considered self-fruitful or self-pollinating. Other types of trees require pollen from a different variety of the same type of tree and are considered self-unfruitful or self-incompatible. The transfer of pollen from one variety to a different variety of the same type of tree is called cross- pollination. Cross-pollination is essential for apples, pears, most sweet cherries, and most Japanese plums. Cross-pollination is not essential, but does improve the number of fruit that form on apricots, European plums/prunes, tart cherries, peaches and nectarines.

Pollen is primarily transferred by honeybees. Trees placed more than 100 feet away may result in poor pollination. Bees work best when temperatures are above 65oF. Cool weather, rain or winds may prevent bees from leaving their hives. Most pesticides are toxic to bees and should not be used during bloom time. For more about honey bee pollination in orchards, including placement, numbers of hives, ways to enhance bee habitat and pesticide effects on honey bees visit our page on Honey bees.

Apple Pollinizer Information

All varieties of apple trees require some cross-pollination for fruit set. Even though some varieties are listed as self-fruitful, they will set fruit more heavily and more regularly if they are cross-pollinated. Flowering crabapples (see variety list below) have become popular pollen donors because they generally have longer bloom times than apples and are easily cared for.

Good Crabapple Pollinizers:
  • Crimson Gold – Blooms midseason to late
  • Indian Summer – Blooms with King bloom of Reds
  • Manchurian  –  Blooms early to midseason (linked to certain postharvest rots)
  • Mt. Blanc™ (x6114 cv.) – Blooms late
  • Mt. Evereste™ (permute cv.) – Blooms early to midseason (scab resistant)
  • Snodrift – Blooms midseason to late
  • Whitney Crabapple
  • Wickson Crabapple
There are some apple varieties that cannot be used as pollinizers:
  • Baldwin
  • Gravenstein
  • Jonagold
  • King
  • Mutsu
  • Winesap
Apple Bloom Chart

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Pollen Compatibility Chart

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W-D_Apple-bloom-chart Apple-pollen-chart

Resources

 

Pear Pollinizer Information

Pear blossoms have a short season and the small amount of nectar produced is not attractive to bees. Twice as many bees should be available to pears than for other fruits. Move bees into the pear orchard when the trees are in one-third bloom.

Although Anjou and Bartlett are partially self-fruitful, they should be cross-pollinated to produce heavy and regular crops. Bartlett, Comice and Hardy may set large crops of parthenocarpic fruit. European and Asian pears will cross-pollinate if blooming at the same time.

 European Pears

Pear Fruiting Variety

Compatible Pollinizer

Anjou Bartlett, Bosc, Comice, Anjou*, Seckel
Bartlett Anjou, Bosc, Comice
Bosc Anjou, Bartlett, Comice, Seckel
Comice Anjou, Bartlett, Bosc, Seckel
Seckel Bosc, Comice, Bartlett

Asian Pears

Asian Pear Fruiting Variety

Compatible Pollinizer

Chojuro Shinseike, Bartlett
Nijisseiki (20th Century) Chojuro, Shinseike, Bartlett
Hosui Partially self-fruitful; any other pear in same bloom time OK.
Shinseike Chojuro

Resources

Cherry Pollinizer Information

Most sweet cherry varieties are self-unfruitful (self-incompatible, SI) and require cross pollination with another variety as the pollen source.

Some varieties, e.g. Bing, Lambert, Royal Ann/Napoleon, are also cross-unfruitful and cannot be depended upon to provide pollen for each other. Index, Lapins, Skeena, Sweetheart, White Gold, Sonata, Stella, Symphony, Sunburst, and Black Gold are self-fruitful (SF) and can serve as “universal” pollen sources for many self-unfruitful varieties with the same bloom time. However, Stella has been found to not work as a pollinator for Bing in some areas.

Their use as “universal” pollinators should also take bloom timing into consideration as follows. Early-bloom: SI – Somerset; SF – Lapins and Skeena. Early- to early-mid-bloom: SI – Kristin, Chelan, and Black Republican; SF – Sweetheart and WhiteGold. Mid- to late-mid-bloom: SI – Royalton, Summit, Ranier, Royal Ann / Napoleon, Bing, Burlat, Van, Regina, Lambert, Sam, and Windsor; SF – Sonata, Stella, Symphony, and Sunburst. Late-bloom: SI – Gold and Hudson; SF – BlackGold. Move bees into orchards on the first day of bloom. The pollination table below is a partial guide to help select pollen source parents.

Pollen Compatibility Table

Fruiting variety

Compatible Pollinizers

Bing Sam, Van, Montmorency*, Rainier, Stella, Compact Stella, Garden Bing
Lambert Sam, Van, Montmorency, Rainier, Stella, Compact Stella, Garden Bing
Rainier Sam, Van, Bing, Royal Ann, Lambert, Montmorency, Stella, Compact Stella, Garden Bing
Royal Ann Sam, Van, Montmorency, Rainier, Stella, Compact Stella, Garden Bing
Stella, Compact Stella, Garden Bing Self-fruitful
Van Sam, Bing, Royal Ann, Lambert, Montmorency, Rainier, Stella, Compact Stella, Garden Bing
Montmorency (*tart cherry) Self-fruitful

Resources

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