Fruit tree pollination facts for kids
Pollination is super important for fruit trees to grow yummy fruits and seeds! It's like moving tiny dust (called pollen) from one part of a flower (the anther) to another part (the stigma). This can happen within the same flower or between different flowers. Some fruit trees need pollen from a different tree to make fruit. These are called "pollinizer" trees and are often planted nearby in orchards.
Pollen needs a way to travel. It can be carried by animals (like bees!), by the wind, or even by people (this is called hand-pollination). When pollen moves between different types of plants, it's called cross-pollination. This helps create new seeds with different traits, which is how new and improved fruit varieties are developed. Trees that are cross-pollinated, especially by insects like bees, usually produce more fruit. Bees are super important helpers for fruit trees!
People have studied fruit tree pollination for hundreds of years. We know a lot about how it works in places with temperate climates (like where apples and cherries grow). But we're still learning about it in tropical climates (where fruits like bananas and mangoes grow).
Contents
Temperate Fruits: How They Get Pollinated
Apples: Busy Bees and Special Friends
Most apple trees can't make fruit with their own pollen. This means they need pollen from a different apple tree variety to grow apples. A few types can self-pollinate, but even they grow more apples if they get help from another tree. Some apple varieties are "triploid," which means their pollen isn't very good for other trees.
To make sure apples grow well, farmers need to plan for "pollenizers." These are apple or crabapple trees that produce lots of good pollen. Farmers might plant rows of different apple varieties next to each other, or even graft (attach) crabapple branches onto apple trees. If there aren't enough pollenizer trees nearby, growers sometimes bring in buckets of crabapple blossoms to help.
During apple bloom season, farmers often bring in honeybee hives. Honeybees are the most common pollinators for apples in many places. But wild bees, like mining bees (Andrena) and Bumble bees, also help a lot, especially in home gardens.
Recently, Orchard bees (also called mason bees, like Osmia rufa or Osmia lignaria) have become popular. These bees are super efficient pollinators, sometimes 100 times better than honeybees! This means you need far fewer mason bees to pollinate a whole orchard. They also rarely sting, which makes them great for home gardens.
How do you know if an apple tree got enough pollination? The apples might be small, oddly shaped, or ripen slowly. Well-pollinated apples usually have 7 to 10 seeds inside. Apples with fewer than three seeds often drop off the tree early. Not enough pollination can happen if there aren't enough pollinators, pollenizer trees, or if the weather is bad during bloom time.
Pears: Not as Sweet for Bees?
Like apples, pears usually need pollen from another pear tree to make fruit. But pear blossoms are not as attractive to honeybees as apple blossoms. They have lighter colors and a milder smell. Bees might even fly past pear trees to visit dandelions or a nearby apple orchard!
Most pear pollination is done by honey bees, but blow flies and hoverflies also visit them. To get honeybees to pollinate pears, farmers sometimes use special scents that attract bees. Another trick is to bring in a huge number of beehives (called saturation pollination) so the bees have no choice but to visit the pear blossoms. Or, they might wait until about 30% of the pear flowers are open before bringing in the bees.
Plums and Prunes: Different Needs
Most Asian plums need a second variety of plum tree for cross-pollination. But most European plums can self-pollinate. European plums that dry well are called prunes. Some Asian plums bloom very early. If too many fruits grow, they need to be thinned out so the branches don't break.
Apricots: Early Bloomers
Apricots are similar to almonds and often bloom early in the year. If they produce too much fruit, it's important to thin them out so the tree can grow healthy, full-sized apricots.
Peaches and Nectarines: Mostly Self-Sufficient
Most peach and nectarine trees can self-pollinate. This means they don't need as many pollinators as apples and pears.
Cherries: Sweet and Sour
Sour cherries (also called pie cherries) can self-pollinate. However, they might produce even more fruit with help from pollinators. Most sweet cherries need a second variety of cherry tree for pollination. Even self-fertile sweet cherries do better with a partner tree. Sour cherries can even help pollinate sweet cherries! Cherry trees usually don't need fruit thinning.
Figs: Tiny Wasps Help Out
Some fig trees can produce fruit without any pollination. But for figs that do need pollination, tiny fig wasps are the special helpers!
Temperate Nuts: Pollination Stories
Almonds: A Million Bees!
Most California Almond trees cannot pollinate themselves. They need pollen from a different almond variety to grow nuts. Pollination during the bloom period is the most important thing for a good almond crop. More than a million honeybee colonies are brought to California almond orchards each year! Beekeepers from all over the country bring their bees to help.
Farmers usually aim for 2 to 3 beehives per acre. But sometimes, there aren't enough bees. In these cases, growers might use special sprays that make bees spend more time foraging and pollinating flowers throughout the orchard.
Scientists have also developed new "self-fertile" almond varieties. These trees don't need a different almond tree for pollination, but they still need insects (like bees) to help them produce a good crop. Growers with these new varieties often use fewer bees and still get excellent nut yields.
Wind-Pollinated Nuts: Let the Wind Blow!
Hazelnuts (filberts), walnuts, pecans, and chestnuts are all nuts from temperate areas that are pollinated by wind. For most of these, you need two different varieties and good windy weather for cross-pollination. Insects and birds might visit these trees, but they don't help with pollination.
Some edible seeds from cone-bearing trees like pine and ginkgo are also called nuts, and they are also wind-pollinated.
Tropical Fruits and Nuts: Different Ways to Pollinate
Citrus: Seedless or Seedy?
Many citrus fruits (like some oranges and lemons) don't need pollination to grow fruit. They are often seedless! Some citrus can produce fruit either way: with seeds if pollinated, and without seeds if not. Citrus that needs pollination can often self-pollinate, meaning the pollen just needs to move a short distance on the same flower.
If you have a citrus plant indoors, like a Meyer Lemon, it might drop its blossoms because there are no pollinators. You can help by hand-pollinating them yourself!
A few citrus types, like some tangelos and tangerines, cannot self-pollinate. They need cross-pollination from another citrus tree. Farmers plan for this when planting groves and often use honeybee hives to ensure good pollination.
Papayas: Mystery Pollinators
Most papaya varieties have separate male and female plants. You need both types for fruit to grow. Some papayas can self-pollinate because they have flowers with both male and female parts. A fully grown papaya fruit can have over 1,000 seeds, so a lot of pollen is needed!
We don't have an exact list of all the animals that pollinate papayas. Large insects like hawkmoths and sphinx moths, and possibly hummingbirds, are thought to be the main pollinators. Honeybees visit papaya flowers for nectar and pollen, but the shape of the flowers might make it hard for them to be the main pollinators. Still, farmers often place beehives near papaya groves to help with pollination. Early on, people thought wind and gravity helped, but modern studies haven't confirmed this.
Passion Fruit: Quick Blooms
Most edible passion fruit varieties can self-pollinate. Each flower is only open for 1 or 2 days, so sometimes insects don't get a chance to pollinate them. You can help by hand-pollinating to get more fruit.
Mangoes: Grafting for Growth
Mango trees usually self-pollinate. They are also often grown by grafting, which means attaching a part of one mango tree onto another.
See also
In Spanish: Floración, polinización y cuaje en árboles frutales para niños
