2019 ASHS Annual Conference

Highbush blueberry (Vaccinium corymbosum) is an economically important crop across North America and has become important worldwide. Washington State is one of the largest blueberry producers in the United States. Yield in western Washington is on average lower than eastern Washington and this may be partially due to poor pollination in the western part of the state. A previous study has shown that increased honey bee (Apis mellifera) hive density can promote pollination, subsequent berry mass, and estimated yields in ‘Duke’ grown in western Washington. While these results are promising, additional research on higher hive densities and more cultivars is warranted to confirm the results and identify the point of diminishing returns. The overall objective of this project is to evaluate the effects of modified honey bee hive densities on pollination, fruit set, estimated yield, and fruit quality attributes in blueberry grown in western Washington. Three different hive densities [10 (control; standard grower practice), 20, and 25 hives/ha] were introduced to ‘Draper’ and ‘Duke’ blueberry fields at 5% bloom. Honey bee visitation, fruit set, average berry mass, seed number, firmness, °Brix, and estimated yield/bush were measured in 2018. Results showed that both 20 and 25 hives/ha increased both honey bee visitation and fruit set, and 25 hives/ha had the highest honey bee visitation and fruit set in ‘Draper’ and ‘Duke’ blueberry compared to the control treatment of 10 hives/ha. An important trend was observed whereby the higher hive density sites tended to have greater yields. Although yield was not significantly different by treatment, this numerical difference in yield may be economically important for growers. This work is ongoing and will be repeated in 2019, but results continue to demonstrate increasing honey bee hive densities is a promising strategy to improve production in pollination-limited western Washington.