The stigmatic lobes open gradually in the afternoon and are not fully open until the second or even the third day. By then, the anthers of the same flower have shriveled and no longer produce pollen. Once open, the stigma may then be receptive for more than 2 weeks. Although beets are basically wind pollinated, some benefit may be derived from insect pollination. The lengthy period that the stigma is receptive to pollen doubtless contributes to the chances that windborne pollen will encounter it in time to effect fertilization and the production of seed.
Wind is doubtless the major pollinating agent of beets.
The finding of numerous honey bees or wild bees on beet flowers in the United States is unlikely if there is other pollen available in the area. Although the evidence indicates that pollinating insects may cause some increase in beet seed yields, their value is given no consideration in the usual recommendations for beet seed production. The evidence indicates that they may be beneficial, and for that reason their activity in flowering beet fields should be encouraged. SHAW, H. B. 1914. Sugar Beet Tech.