SKAGIT VALLEY HERALD – AARON WEINBERG
MOUNT VERNON — The European honeybees used by beekeepers aren’t very good at pollinating blueberries.
That poses a problem for blueberry farmers because pollination helps boost a crop’s yield.
“Honeybees are important for pollinating crops, blueberries among them,” said Lisa DeVetter, assistant professor at the Washington State University Mount Vernon Research Center. “It initiates a cascade of fruit development.”
Since 2014, DeVetter has researched the problem of pollinating blueberries. Her work has helped blueberry farmers get better results during the important two-week bloom and pollination window.
Blueberry bushes start blossoming in the spring. Depending on the variety, the white flowers are usually so small that it’s hard for honeybees to land on them.
“They land, they fall and sometimes are successful but often aren’t,” DeVetter said. “If they get lucky and land on the flower they often can’t fit their head in to pollinate it.”
Honeybees also won’t stray too far from their hive. Knowing this, DeVetter has found one promising tactic for increasing pollination success — dispersing honeybee hives throughout a crop rather than clustering them together.
“What we found is that the further you get from the hive, fruit size drops linearly,” she said.
Her findings showed that dispersing hives throughout the field increased fruit yield 2.65 pounds per plant.
Bow Hill Blueberries owner Harley Soltes said that after learning of DeVetter’s findings, his farm will start spreading bee hives throughout its fields.
“We used to put them close together in a spot that would heat up the fastest in the morning,” he said.
Soltes also makes efforts to enhance habitat for native pollinators such as bumblebees and the much smaller mason bees.
“Between … our own wildflowers and blossoming weeds, we provide good food for the bees year-round,” he said.
Bumblebees and mason bees, which live in underground hives, are much better at pollinating blueberries, said DeVetter.
Bumblebees, although much larger than European honeybees, can pollinate blueberries reliably because they can vibrate their flight muscles, causing pollen to release from the flower.
Mason bees, meanwhile, are small enough to fit inside a blueberry flower.
The problem with those species is that they aren’t available commercially in the region.
And even if they were, DeVetter doesn’t know if they would help farmers much based on her team’s preliminary work on bumblebees in 2016.
That year, she rented a bumblebee hive from a local beekeeper to test its impact on crop yield. Her team didn’t see an increase, but they did make one interesting finding.
“We did see more honeybee activity, maybe because of the increased competition with the bumblebees,” DeVetter said.
Her ongoing research will examine ways to further promote native pollinators and will also seek to gather more information on how weather impacts the timing of pollination.
She said the work has been rewarding, even if she and her team have to endure a few bee stings every now and then.
“Growers are interested in this,” she said. “We can take a few stings.”