Bluecrop flowers were just robbing them of nectar without pollinating the flowers, leaving a pollination deficit in this cultivar.
It was estimated losses for growers
could be as high as $18,000 per hectare in income annually because of insufficient pollination in Bluecrop, unless there is semi-wild land nearby where bumble bees could browse all season. Interestingly, growers who care about conservation of wild land around their fields tend to have better pollination because of the need for wild bumble bees to have forage nearby before and after blueberries flower, she comments. Wild pollinators are needed to maximize yields by supplementing honey bee pollination in many pollinator-dependent agricultural systems, but this is particularly true to achieve high yields in blueberry fields.
Unfortunately, some bumble bees are in decline just as honey bees are, she warns. There’s new evidence for a spillover of disease from domestic honey bees into wild bee populations, and some species of bumble bees have a higher pathogen load than in years past.
To make a difference, people can plant a garden which provides a variety of colours, shapes and sizes of flowers with different and extended bloom times, so bees always have forage available to keep them alive.
Another problem that affects the abundance and diversity of wild bees, is invasive plants, which also often create a mono-culture, presenting bloom for a brief time, then dying off and leaving bees without forage throughout the season.
Bee pastures near berry fields improve yields in Michigan, Elle notes, and her group is attempting to establish such pastures in B.C. to evaluate how well they work in this region.
The Integrated Crop Pollination project, funded by the U.S. Department of Agriculture, is looking for ways to provide better pollination insurance for growers through the combination of honey bees, other managed bees and support for wild bees. For more information, go to
icpbees.org
16 British Columbia Berry Grower • Summer 2016
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