Avocado Pollination

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What Is Pollination?

As beekeepers, we know that honeybees are instrumental in pollinating the majority of the foods that we humans need and value, such as our many fruits, vegetables, and legumes.  In fact, according to Google, bees and other pollinators affect 35 percent of global agricultural land, supporting the production of 87 of the leading food crops worldwide!  Wikipedia’s list of crop plants pollinated by bees is extensively long.

Honeybees also pollinate many other types of trees and plants throughout the natural world.  In fact, honeybees are one of the most industrious pollinators on the planet, and critical to the success of much of human agriculture.

But what exactly is pollination, and what is actually going on when honeybees pollinate flowers?

When we humans admire the beauty of flowers, we rarely stop to consider that flowers are the sexual organs of plants.  There are male flowers, and there are female flowers.  The goal of nature is to move the genetic material from the male to the female.  Pollination is the transfer of male microspores from a male flower to the ovule of a female flower.  This is the sexual reproduction of a plant, ultimately resulting in the creation of a seed.

A male flower features what is called a stamen.  This is the part of the male flower that produces pollen.  A female flower features what is called the pistil.  The tip of the pistil, called the stigma, receives the pollen and transfers the pollen down the pistil to the flower’s ovule, fertilizing it and enabling the formation of a fruit or some other carrier of the plant’s seed, such as a pod, a vegetable, or just a seed itself.

The honeybee’s role in all of this is to transfer the pollen from male flower to female flower.  Some plants and trees have both male and female flowers on the same tree (monoecious) or male flowers on one tree and female flowers on another (dioecious).  Either way, a honeybee doesn’t seem to care much.  She just goes from flower to flower, plant to plant, looking for nectar, and in the process inadvertently transfers tiny pieces of pollen from male flowers to female flowers without that even being her goal.

It is most likely that the main reason that flowers look so appealing, and feature such sweet nectar, is to attract animals to pollinate them.  The sweeter the nectar that a plant produces, the bigger the lure for honeybees and other insect pollinators, such as bumblebees, orchard bees, squash bees and solitary bees, to visit.

Honeybees are not the only animal pollinators of plants.  Any animal that visits flowers contributes to pollination – hummingbirds, bats, butterflies, ladybugs, beetles and other insects – also pollinate.  Sadly, like honeybees, many of these beneficial pollinators are under environmental stress, and face ongoing population decline.

There are some plants, however, that do not rely on animals for pollination, but rather are wind pollinated, such as the grasses of corn, wheat, and rice.  It is noteworthy, that unlike animal-pollinated blossoms, which are almost always colorful and sweet, these wind-pollinated blossoms look exceedingly dull and contain no nectar.  This is because they have no incentive to attract pollinating animals, such as honeybees.  Instead, the goal of wind pollinated plants is simply to produce as much pollen as possible and throw the pollen into the wind, hoping that it hits its target.

As beekeepers, we may be a bit biased, but we much prefer flower pollination by bees, as just thinking about windward grass pollen make us want to sneeze!

Pesticide Spraying

Every spring, around late May, more or less, comes the dreaded phone call: “Hi, we just wanted to let you know that we will be spraying the grove at . . . ____ .  We know that you have bees in the area and want to give you a chance to move them out before we begin pesticide spraying.”

While perfectly courteous and respectful, this call and those like them are particularly bothersome here at Wildflower Meadows.  Oftentimes, the yard in question has a group of emerging virgin queens that are just getting oriented to the area.  Other times, the colonies in the yard just received a batch of sensitive queen cells.  At these critical points, it can be detrimental to have to move a colony of bees to a new location.  Yet, they have to be moved.  And, typically, we lose the queens when this happens.

The other challenge of receiving late May spray calls is the unfortunate timing.  Late May is usually the end of our busiest season.  Our crews are growing tired from working long hours since late March, and now have a new, unexpected project to tackle.  Of course the days are long at this time of year, so we have to wait until the sun finally sets to begin the moving process.

The final blow often takes place after we ultimately move the bees to what we think is a safe location, then receive a new incoming call of: “Hi, we see that you just moved bees into the area.  We plan on spraying there next week  . . . ”

 

 

Migratory Beekeeping

Some of our largest customers at Wildflower Meadows are migratory beekeepers.  Migratory beekeepers in the United States begin each new year in California pollinating almonds.  After that their paths diverge.  Some move their bees to orange groves to produce orange blossom honey.  Other beekeepers continue on to Oregon and Washington to pollinate cherries, cranberries, and apples.  By summer, many of these same beekeepers can be found in the Great Plains producing clover honey.  In the fall and winter, most of these very same beekeepers move their bees to warmer climates, like these here in Southern California, for over-wintering.

What makes all this possible is the existence of the vast United States interstate highway system, the availability of large flatbed trucks, and forklifts.  Migratory beekeepers keep their bees on pallets, usually four to a pallet – most usually known as “four-ways.”  The pallet doubles as a bottom board for the colonies, each of which are held in place by clips.  When it comes time to move the bees, the beekeeper can easily pick up a pallet of four colonies at a single time with a forklift.  Giant 18-wheel flatbed trucks are loaded with upwards of 400 colonies each.  Depending on the distance of the move, the load is netted down, and the truckers head on their way to more abundant pastures.

While migratory beekeeping benefits the bees in certain ways – the bees always find themselves in the midst of flowering crops or fields – it is hard on them in other ways.  The constant moving can lead to stress, which can result in queen losses.  And, keeping bees on pallets and in close quarters is not necessarily ideal because it can lead to the spread of mites and diseases.

Migratory beekeeping can also be hard on the beekeepers, who spend large amounts of the year away from home and family.  The life of a migratory beekeeper features many days on the road, staying in cheap hotels, eating fast food, and almost all of the of time worrying about planning and logistics.

Despite all this hardship, not enough praise can be offered to these brave beekeepers, and the contributions that they make to our food supply.  Without migratory beekeepers and their invaluable pollination services, our crops would suffer greatly – and we would too.  Migratory beekeepers are among the true heroes of beekeeping!

Photo courtesy of Allen’s Honey Company, Brawley, California, pollinators of almonds, melons, alfalfa and countless vegetable seed crops.

Orange Blossom Honey

California has many well-documented problems: wildfires, traffic jams, and earthquakes immediately come to mind.  On the other hand, however, California has orange blossom honey!

Beginning around the middle of March and lasting until about the middle of April, citrus trees – including orange, tangerine, lemons, limes, and grapefruit – all blossom in full force, emitting the sweet aroma of citrus bloom.  A walk inside a blossoming citrus grove is a sensory experience to behold:  beautiful spring weather, bright green leaves, spectacular aroma, and happy honeybees buzzing everywhere.

During springtime in California, with many types of wildflowers blooming, honeybees have countless options of where to forage.  Typically, however, one of their first choices are the orange trees, and who can blame them?

In Southern California, a downside of orange blossoms flowering in March, if there can be one, is that a strong nectar flow of citrus trees can draw bees away from nearby blooming avocado trees.  This dual blooming has the potential to impair nearby avocado pollination.  Avocado farmers who neighbor flowering citrus trees need to be aware of the competition for their bees, and compensate by keeping extra colonies of honeybees in their avocado groves to pollinate their trees.

Avocado Pollination

Avocado blossoms bloom in two stages.  In the first stage, flowers open as a female.  In other words they do not produce pollen, but receive pollen.   In the second stage, which takes place about three to four hours later (or the next day) the flower opens as a male.  The stigma of the male flower releases pollen.  Some tree varieties have flowers that start the day as a female, and other varieties have those that start the day as a male.  In both cases, the flowers switch over mid-day.  On cloudy or overcast days, however, neither type of flower will open in the morning, delaying the start of pollination.  When the sun finally does appear, some trees may have both male and female flowers blooming at the same time!

A mature avocado tree may bear a million flowers in a single season.  It is no secret that good pollination improves both the yield and quality of avocados.  Although avocados are partially self-pollinating, visits by honeybees have been proven beneficial because honeybees transfer large amounts of pollen from flower to flower, tree to tree.  It has been estimated that up to 90% of an avocado crop would be lost in the event there were no honeybees.  Many commercial avocado growers in California contract to rent thousands of beehives for improved pollination and yield.  An estimated 105,000 colonies per year are rented in the United States specifically to improve avocado pollination.