Echium As An Oilseed Crop in Minnesota: Flowering Dates, Pollinators, and Seed Yields.

Echium (Echium plantagineum) can be a serious winter annual weed in Mediterranean-type environments. However, it also can be an alternative oilseed crop in summer-wet temperate regions. It produces seed oils rich in omega-3 fatty acids. One of these is stearidonic acid, which is desired highly by the cosmetic industry. In North America, only a single study has reported anthesis date and seed yield, and none has documented pollinator visitation. We examined these three variables in a planting date study over two years in western Minnesota, which has a summer-wet temperate climate. Seeds were sown in field plots in spring or early summer, flower abundance and insect visitors were noted weekly, and seed yields were determined near the end of the growing season. April- or May-sown echium produced 4X to 29X more seeds than June- or July-sown echium, with maximum seed yields > 750 kg/ha. (Profitable yields are ≥ 250 kg/ha.) Initial flowering commenced 41 to 55 d after sowing, and anthesis duration (first flowering to harvest) was 34 to 70 d. Initial flowers attracted hoverflies (Syrphidae). Subsequent flowers, however, attracted large numbers of honey bees (Apidae), which represented about 50% of all insect visitors. Early-sown echium in Minnesota can flower as soon as mid June, provide abundant floral resources for honey bees for two months, and produce seed yields 200% greater than the breakeven point. Spring-sown echium and/or seeds lost through shattering showed no signs of over-winter survival or weedy behavior the following year.