Bluecrop pollination

The Bluecrop variety of blueberry presents unique challenges in setting fruit. In a year when there are few bees it is not uncommon to see bees drawing nectar for the base of a flower that has become separated from the base. This, of course, subverts the whole process of pollination. In a year like this year, when there are lots of bees, foraging without pollinating is never seen. A plausible explanation is the following:

Dr. Gary C. Pavlis

County Agricultural Agent

Pollination: Unfortunately not all of the visitations to blueberry flowers by bees result in pollination. Pollen must be transferred from some parts of the bee’s body, usually the head to the tip of the pistil (stigma) in order to achieve pollination. There are three ways in which honeybees “cheat” the grower by not earning their rental fee. 1) Acquire nectar by feeding through hole in blossom made by a carpenter bee. 2) The distance from the edge of a flower petal to pistil is very wide, as in Earliblue. The bee can stick its tongue down and get the nectar without touching the pistil. 3)The bee does not thrust through the open end but gets nectar through the bottom – very important in Bluecrop and Jersey. In some years such a high percentage of the bees may work through the bottom of the corolla that the crop can be significantly reduced. Bees develop this bad habit mostly on Jerseys and Bluecrop. The probable reason is that both of these varieties can produce small seedless berries without pollination (parthenocarpy). These parthenocarpy berries begin to develop shortly after the flowers open and once it starts the corolla becomes loose at the base after a few days, enabling the bee to secure its nectar through the loose juncture of the corolla and ovary. Since the honeybees usually select older flowers which have more nectar it enables the younger ones to start the parthenocarpic process which does not occur once the flower is pollinated. The solution may be to use higher concentrations of bee hives.

The higher numbers of bees per bush forces them to accept younger flowers with the result that more berries are developed from bee pollination than by parthenocarpy.

Source:  http://njaes.rutgers.edu/pubs/blueberrybulletin/2009/bb-v25n06.pdf

 

Anise Hyssop – greenhouse to garden

Shade is needed to help the Hyssop transition from the greenhouse to outdoors.

Anise Hyssop from seed

Transplanted outdoors

Worker Bumblebees

The population of worker bumblebees seems to peak at about the time of the full bloom in the Elliott blueberry. These small bumblebees seem to rival the number of honeybees as you walk through the field. In a few days the honeybees will be distracted by the thornless blackberries so the bumblebees play an important role in pollination.

worker bumblebee

Bees and Blueberries

The past week has been the peak time for pollinating blueberries. Except for rhododendrons the blueberry bushes have had the bees to themselves. The mountain ash and wild apple were finished pollination about a week ago and the thornless blackberry have just started to show flowers. The bees are very attracted to the blackberry blossoms.

The worker bumblebees have been around for a couple of weeks and are now showing up in greater numbers and the honeybee colonies have expanded greatly over the past month.

Rhododendrons attract many bees.

Mason bees at work

Blueberry blossoms are at their peak and the Mason bees are still at work. This nest is in some rows of Bluecrop to boost the chances of a good fruit set.

Mason bee entering nest

Mason bee exiting nest

Competing for bees – and winning

As you approach these trees you can hear the bees before you see them. Early blueberries, that are in full bloom, don’t stand up well to this competition.

oak in bloom

mountain ash

wild apple

The queen bumblebees are still at work in the blueberries. We are waiting, and hoping for, a good population of worker bumblebees.

What the bees are buzzing about.

Just when the first blueberries come into bloom the bees find other plants more exciting.

June blueberry - full bloom

Patriot blueberry - full bloom

The dandelions are going to seed but the oak is alive with bees.

dandelion

Oak blossoms

Wild apples abound in the area and fruit trees are in bloom.

wild apple

Transparent apple

Honeybees will move to where the foraging is easiest but Bumblebees have a less varied taste. They tend to stick with the blueberries.

 

                                                                                                                      

Wild bees of Michigan

Native bees can be a big help in pollinating blueberries. With not much effort the population of Bumblebees and Mason bees can be increased by growing Anise Hyssop for the bumblebees and providing nests for the Mason bees. A study in Michigan found lots of wild bees.

Julianna Tuell, a postdoctoral Michigan State University entomology researcher who studies pollinating insects, was surprised at what she found in the blueberry fields of southwestern Michigan.

“We found 112 species during blueberry bloom, and 166 species overall,” Tuell said. “They aren’t all visiting blueberries, but at least half of them are contributing to pollination. There’s a really wide diversity of bees across the season, with some that provide pollination during bloom and are also active later in the season.”

 The research team also found seven bee species that had not previously been found as far north as Michigan. These findings, which have been published in the Annals of the Entomological Society of America, not only point to a more diverse ecosystem in the managed blueberry fields, but they also mean that growers may have more options than previously thought for pollinating their crops.

 “We encourage growers to think about integrated crop pollination,” Tuell said. “The grower brings in managed bees but does things to encourage natural pollinators and modifies some practices to help beneficial insects. Growers are interested and surprised by how many bees are out there.”

Michigan wild bee

Source:http://news.msu.edu/story/6317/