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United States Department of Agriculture

Agricultural Research Service

Title: Toxic alkaloid concentrations in Delphinium nuttallianum, D. andersonii, and D. geyeri in the Intermountain region

Authors
item Gardner, Dale
item Pfister, James

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2007
Publication Date: July 1, 2007
Repository URL: http://srmjournals.org
Citation: Gardner, D.R., Pfister, J.A. 2007. Toxic alkaloid concentrations in Delphinium nuttallianum, D. andersonii, and D. geyeri in the Intermountain region. Vol. 60 Issue 4 pp.441-446.

Interpretive Summary: Low larkspurs often poison grazing cattle on western North American rangelands. The dominant toxic alkaloid in low larkspurs and plains larkspur is methyllycaconitine (MLA); another very toxic alkaloid in low larkspurs is nudicauline. Low larkspurs (Delphinium nuttallianum from Utah and Colorado, D. andersonii from northern Arizona), and plains larkspur (D. geyeri from Wyoming) were collected for analysis. Concentrations of toxic alkaloids greater than 3 mg/g in these plants indicate at least moderate toxicity. Concentration of MLA in low larkspur ranged from 0.8 to > 4 mg/g in Utah and Colorado. Concentrations of toxic alkaloids in low larkspurs varied by location and growth stage. Low larkspur from the Arizona Strip was consistently toxic because the concentration of nudicauline was equal to or greater than MLA at each growth stage. The combined concentration of MLA and nudicauline exceeded 4 mg/g during the vegetative stage, and was approximately 3 mg/g during the flower stage. MLA concentration in plains larkspur was typically highest (2 to 4 mg/g) in immature plants, although MLA concentrations in plants during the pod stage of growth sometimes increased. Essentially no nudicauline was found in plains larkspurs. Concentrations of toxic alkaloids in low and plains larkspur often did not significantly decline during the growing season as typically found in tall larkspurs. Thus, risk to grazing cattle from poisoning by these plants may remain high until these plants are completely dormant.

Technical Abstract: Low larkspurs (Delphinium nuttalliunum, D. andersonii) and plains larkspur (D. geyeri) are serious poisoning threats to cattle grazing on western North American rangelands. The dominant toxic alkaloid in low larkspurs and plains larkspur is methyllycaconitine (MLA); another very toxic alkaloid in low larkspurs is nudicauline. D. nuttallianum from Utah and Colorado, D. andersonii from northern Arizona, and plains larkspur (D. geyeri) from Wyoming were collected for analysis. Concentration of MLA in D. nuttallianum ranged from 0.8 to > 4 mg/g in Utah and Colorado. Delphinium nuttallianum tended to differ (P=0.09) in MLA concentration between locations, but not phenological stages (P=0.41). Concentrations of nudicauline ranged from 0.7 to 4 mg/g in D. nuttallianum and were different (P=0.01) between locations and phenological stages (P=0.004). D. andersonii was consistently toxic because the concentration of nudicauline in D. andersonii was equal to or greater than MLA at each phenological stage. The combined concentration of MLA and nudicauline exceeded 4 mg/g during the vegetative stage, and was approximately 3 mg/g during the flower stage. MLA concentration in D. geyeri was typically highest (2 to 4 mg/g) in immature plants, although MLA concentrations in plants during the pod stage of growth sometimes increased. Essentially no nudicauline was found in D. geyeri. Concentrations of toxic alkaloids in Delphinium nuttalliunum, D. andersonii and D. geyeri often did not significantly decline during the growing season as typically found in tall larkspurs. Thus, risk to grazing cattle from poisoning by these plants may remain high until these plants are completely dormant.

Last Modified: 11/23/2014
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