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The A Bees Cs of Pollinations

It takes two species for fruit trees to blossom

A Bay Weekly reader complains that her apple trees have not produced any fruit during the five years that she has had them in her garden. All five, she told me, are of the same variety: golden delicious trees. She was told that for the trees to produce fruit, she needed to plant more than one tree. Since her preference was for Golden Delicious, that is what she purchased and planted.

Help Bluebirds
Help You

    Bluebirds are great to have around the garden because they are primarily insect eaters. Having a few bluebird houses can help reduce your garden insect problems. Set the boxes approximately 300 feet apart.
    The first brood has left the nest, and mother bluebird is now getting ready to prepare a nesting box for her second brood. I help her by cleaning out the bluebird nesting boxes and spraying the inside with a 10 percent bleach solution to kill the mites that invade nesting birds.
    Lothian Ruritans build bluebird nesting boxes and sell them for $15 each. Get yours in time for this year’s second brood at ­www.lothianruritans.org.

    She was traveling to an orchard under bad advice. Golden Delicious is a clone, and clones cannot pollinate themselves. Apples require cross-pollination from a different variety to produce fruit. The pollen from the Golden Delicious apple flower cannot pollinate the stigma of that same flower or an adjoining flower.
    For an apple to be produced by the Golden Delicious apple tree, the pollen has to come from a different variety. She should have planted a Red Delicious, Jonathan, Gala, Granny Smith or such as a pollinator.
    This is where bees come in. In their search for nectar, bees carry pollen on their hind legs. As they enter the flower, the pollen from their hind legs brushes against the stigma of the flower, resulting in cross-pollination. You can do the same thing with a small camel’s hair brush as plant breeders do when their intent is to develop a new variety.
    Even though the pollen is from another variety, the fruit remains Golden Delicious because the flesh of the fruit is maternal, derived from the ovary wall.
    For this reason, all fruit trees are propagated by grafting, budding, tissue culture or cuttings. If you were to plant the seeds from a Golden Delicious apple, you can rest assured that the resulting seedling would not be Golden Delicious. The seedling would be a genetic combination of all the sources of pollen that have contributed to it. We call those Heinz 57 flavors.
    Cross-pollination is essential for nearly all of the fruit we eat. This is why bees are so important in the production of horticultural crops. Butterflies, hummingbirds, flies and many more insects also contribute to the process.


Ask Dr. Gouin your questions at frgouin@erols.com. All questions will appear in Bay Weekly. Please include your name and address.

It doesn't take "two species for fruit trees to blossom." The trees will blossom anyway. They need a different genotype to fertilize the blossoms. (Also - not *two* species - that is definitely incorrect. It should be the same species, but different incompatibility genotypes.)

All are Malus domestica cultivars (i.e., they are of the *same* species). Thus, the article subhead "two species" is inaccurate.