Hive Placement Among Keys to Tapping Bees' Full Potential
Improving honey bee pollination in blueberries can be achieved with some simple steps, according to a Washington State University berry crops assistant professor, providing weather cooperates.
Lisa DeVetter, who is stationed at the Northwestern Washington Research and Extension Center in Mount Vernon, Washington, said the primary pollinating species used in Northwest blueberry production is the honey bee (Apis mellifera). Honey bees are relatively easy to propagate and can build strong colonies rapidly, but don’t perform well under certain weather conditions.
“We get poor foraging activity when air temperatures are at 55 degrees Fahrenheit or below,” she said. “Honey bees also do not forage very well in windy conditions of 12 miles per hour or above. Under those conditions, they don’t want to leave their hives. They also are not very active in providing pollination services when there is precipitation.
“All of these conditions are very prominent in Northwest Washington during the blueberry bloom time,” DeVetter said.
That said, DeVetter outlined several steps growers can take to improve the performance of honey bee pollinators, starting with proper timing and placement of hives.
One key, she said, is to place hives in blueberry fields at five percent bloom.
“If they are placed too early, you run the risk of honeybees developing a foraging relationship with some other flowering plants near your planting and not your blueberry plants,” DeVetter said. “In those cases, the honeybees might be reluctant to return to your blueberries once they bloom, thus reducing pollination.”
Also, she said, placing hives later than 25 percent bloom can result in significant yield-loss potential.
“At that point, your flowers may no longer be receptive to pollination,” she said, “so you’ve lost a lot of potential to develop fruit from the flowers on those plants.
“Timing is critical,” she said. “You want to make sure that you have your hives placed out in your field at that five percent blossom time to make sure that you are maximizing your chances of getting those honey bees to pollinate your blueberry flowers.”
Placing hives in a sheltered, east-facing location with sun exposure can increase the duration of honey bee activity, she said.
“All of these practices can increase the chances of those hives warming up earlier in the day,” she said. “And if they warm up earlier, they are more likely to start foraging earlier, so you maximize and increase the time that they are foraging in your blueberry fields.
“Also, consider elevating your hives,” she said, “again to try and increase the hive temperature and the time they are foraging during the day.”
Another tip involved keeping hive entrances clear of vegetation, which can obstruct the entry and exit of honey bees. DeVetter also advised growers to distribute hives evenly across a field.
“The further your plants are away from the hive, fruit set and overall berry size can drop off dramatically,” she said, noting that she has observed this in some of her research trials.
Common stocking densities in the varieties Duke, Draper and Aurora are anywhere from three to four hives per acre, DeVetter said, with a colony size of 45,000 honey bees per hive being considered a strong and healthy hive. She added that she has observed increased fruit set and yield in the Duke variety when stocked with eight hives per acre in research trials in Washington, which, she said, underscores the need for continued research into how to optimize hive density in Northwest blueberry production.
DeVetter said it also is important to be aware of practices that protect bees from exposure to pesticides applied during bloom time.
“What you can do as a grower is to make sure you are following the pesticide label and look for the EPA Bee Advisory Box,” she said. “That will signify if there are any special precautions that you need to take when applying a particular pesticide in your field, and how to implement those precautions.”
DeVetter said growers also can look over the Oregon State University Extension guide, “How to Reduce Bee Poisoning from Pesticides,” which can be found online at https://catalog.extension.oregonstate.edu/pnw591.
DeVetter closed her presentation by noting that good pollination is essential for obtaining good fruit set, yields and berry size, that honeybees are the primary pollinator utilized in blueberries and that practicing best management practices can enable growers to get the most out of pollinators. |
