Planting date impact on flowering, pollinator visitation, and yield of mass flowering oilseed crops in the Northern Corn Belt

Authors: Eberle, Carrie; Scott, Drew; Gesch, Russell - Russ; Weyers, Sharon; Johnson, Jane; Schneider, Sharon; Forcella, Frank

Submitted to: Agricultural and Forest Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/30/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Low flower abundance in agricultural landscapes is one cause of continued pollinator decline. The summer annual oilseeds borage, calendula, crambe, cuphea, echium, flax, camelina, canola, and sunflower can provide much needed floral resources to support pollinator communities. Timing of when flowers are present can affect their value to pollinators. The 9 oilseed crops were sown across four planting dates (Early May, Mid May, Early June, and Early July) in Morris, MN during the summers of 2013 and 2014. The effect of the different planting dates on crop yield, flower abundance, and pollinator response was measured. All crops maintained yield in at least 2 or more planting dates. Planting date affected when flowers were in bloom and the abundance and duration of blooms. Generally, crops that bloomed later in the season had increased pollinator visitation per bloom. These research findings will help producers interested in growing alternative oilseed crops and supporting pollinators to make management decisions and extension educators, researchers, and ag consultants interested in adopting alternative oilseeds to promote pollinators.

Technical Abstract: Decline in natural pollinator populations are a potential threat to global food supplies. Summer annual oilseeds can provide much needed floral resources to support pollinator communities. Borage (Borage officinalis L.), calendula (Calendula officinalis L.), crambe (Crambe abyssinica Hochst), cuphea (Cuphea viscosissima Jacq. × Cuphea lanceolata W. T. Aiton), echium (Echium plantagineum L.), flax (Linum usitatissimum L.), spring camelina (Camelina sativa (L.) Crantz), spring canola (Brassica napus L), and sunflower [Helianthus annuus L.]) were grown in Morris, MN during the summers of 2013 and 2014. Crops were evaluated for yield, flowering phenology, floral accumulation (flower coverage time × flower area), and pollinator visitation. Each crop was planted on a “standard” planting date of mid-May and additional planting dates of early May, June, and July. Shifting planting dates affected crop yield, flowering phenology, floral accumulation, and pollinator visitation. At least two of the four planting dates supported high yield for all crops. Later planting dates led to later onset of flowering for all crops and decreased total floral accumulation. Despite lower floral accumulation with the later plantings for each crop, insect visitation per unit of floral accumulation increased. The potential ability to maintain high crop yield across a window of planting dates provides growers management options for their fields as well as opportunities to better manage crops for pollinator health on the agronomic landscape.