Stork's Bill (Erodium cicutarium)
By Nicole Vincent and Charles Geddes
Stork's Bill, or redstem filaree, (Erodium cicutarium) is an annual or winter annual broadleaf species introduced from Europe in the 1700s. In Alberta, Stork's Bill has steadily increased in abundance and frequency of occurrence in annual field crops (see figure), in part, because of an increase in conservation tillage. According to the 2017 Alberta Weed Survey, it is on the list of top 25 most abundant weeds in Alberta for the first time.
Stork's Bill can be a serious competitor in legume and potato crops and can reduce yields in cereal, canola and sugar beet crops as well. It also reduces the quality of small-seeded crops, like alfalfa, because the seeds are hard to separate from the crop. Stork's Bill can host a variety of viral, fungal, and insect pathogens, creating issues with green bridging of pathogens between annual crops.
Stork's Bill is a hairy plant with 3-lobed cotyledons. It has an 8 cm taproot with long fibrous secondary roots. True leaves are hairy and carrot-like with the first leaves forming a rosette, then subsequent leaves extending upward on stems up to 40 cm tall. Pinkish-purple, 1 cm wide, 5 petal flowers grow in clusters of 2 to 12 at the top of the stalks. Stork's Bill flowers from June to September and is capable of self-pollination. The fruit forms a tapered column 20 to 50mm long that explosively discharges seeds when mature.
Seeds are hairy, about 6mm long, and have distinct spiraling styles that uncoil in moist weather to drive the seed into the ground and create seed-to-soil contact. Seeds can also be spread by animals, rodents, or insects. Each plant can produce an average of 6000 seeds, but seed production can be highly variable based on emergence date and environmental conditions. Most seeds are still viable after 2.5 years in the soil seed bank but require disturbance to germinate. Stork's Bill achieves the greatest biomass and seed production when germination occurs in May or June because soils are moist and cool, but emergence can occur throughout the growing season and into late fall, allowing overwintering and early flowering. Once established, it is drought-tolerant and can grow in partial shade and low temperatures, allowing it to compete when conditions are not ideal for many crops.
Populations can develop quickly without proper management, increasing 10-fold in 2 years in areas of no-till and no herbicide use. Spring and fall cultivations can destroy seedlings and repeated cultivation can reduce the seed bank by causing flushes of germination. Spring-seeded cereals or fall rye can suppress Stork's Bill and can lead to a reduction in the seed bank if an increased seeding rate is used for several years. Subsurface or seed-placed fertilizer can be effective at reducing weed biomass and the seed bank while ensuring nutrient availability for the crop. Mowing before flowering prevents seed production if the window for other control methods is missed.
Stork's Bill matures very quickly in early spring, so scouting is extremely important to ensure effective timing. Chemical control is most effective at the 2 or 4 leaf stage, so apply herbicide as early as possible. Several herbicides are rated for use on Stork's Bill including group 2 (imazamox, imazethapyr, and florasulam) group 4 (MCPA 2,4-D, dicamba, and fluroxypyr), group 6 (bentazon), and group 9 (glyphosate). Consult your provincial crop protection guide for a full list of herbicide options.
Leeson, J.Y., Hall, L.M., Neeser, C., Tideman, B., and Harker, K.N. 2017. Alberta weed survey of annual crops. Weed Survey Series Publ. 19-1. Agriculture and Agri-Food Canada, Saskatoon, SK. 237 p.
Francis, A., Darbyshire, S. J., Legere, A. and Simard, M.-J. 2012. The Biology of Canadian Weeds. 151. Erodium cicutarium (L.) L'Her. ex Aiton. Can. J. Plant Sci. 92: 1359-1380. DOI: 10.4141/cjps2012-076