Pollination Recommendations and Practices:
All research on sunflower pollination indicates that honey bees are the primary pollinating agents, and that colonies should be provided to the field (Barbier and Abid 1966), and that they should be protected from harmful pesticides while they are in the field. The bees should be ready for the pollination task at the onset of flowering. The total flowering period is usually about 20 days, but 83 percent of the heads begin to open within 3 days after the first head opens. Evidence also indicates that the highest bee population and the highest production occur within a few hundred feet of the apiary. If adequate pollination throughout the field is provided, there should be no significant gradient of seed set in relation to apiary location.
The term "saturation pollination," meaning the patterned distribution of groups of colonies, sometimes used on other crops to provide adequate coverage throughout the entire field, is equally applicable and needed in sunflower production. Cirnu (1960) recommended two colonies per hectare, the bees to be moved in at 3 to 5 percent of bloom. Later, Cirnu and Sanduleac (1965) recommended one colony per hectare. Furgala (1954b) recommended one colony per acre, the colonies placed in rows 300 to 400 yards apart. Smith et al. (1971f recommended one-half colony per acre. The evidence is plain that, if the grower wants maximum seed production, he should not skimp on the use of bees.
The number of colonies per acre alone is not too meaningful. Distribution of colonies to give thorough coverage of all blooms is highly important, and strength and other conditions of the colony are equally important. The criterion the grower should use is the bee visits per floret or bees per head throughout his field. The presence of one bee per head throughout the day should provide adequate visitation, but additional research is needed to determine the exact bee population needed for maximum production of sunflower seed. (1).