Spreading dogbane in hay field. Photo by Josh Putman of Cornell Cooperative Extension.
Spreading dogbane. Photo by Josh Putman of Cornell Cooperative Extension.
Early July, 2020
Josh Putman is Cornell Cooperative Extension’s SWNY Dairy, Livestock & Field Crops representative. He recently ran across this plant in a hay field that had not been worked for a few years. Spreading dogbane, Apocynum androsaemifolium, is in the same family as milkweeds and swallowworts, and the same genus as hemp dogbane. This perennial plant is found in open, dry areas and in disturbed habitats throughout New York and most of the US and Canada.
Leaves: Leaves are oval, 4-6cm (around two inches long), with smooth edges and pinnate veination. They are arranged opposite each other on the branch.
Mature Plant: 0.6m (2 feet) tall, although some sources say 2-5′, with branching reddish stems. Flowers are found at the ends of branches.
Flowers/Fruit: Flowers are bell-shaped with 5 petals that are fused to form the bell and then curl outwards. Flowers can be white as were seen in western NY, but can also be pink or white with pink striping. Fruit are a long, narrow pod up to 11cm (over 4 inches) long; each flower produces two seed pods. Inside the pods are many small seeds with fluffy tufts, much like milkweed or swallowwort seeds.
Toxicity: Dogbanes are reported to be toxic to livestock, containing a compound that interferes with heart function. This toxicity persists when the plant is dried as well as when fresh. There is no specific information on the toxicity of this species to livestock.
Management: Management information for this species in agricultural settings is sparse; most resources discussed it in the context of a native wildflower/shrub. In blueberry fields, nicosulfuron mixed with surfactant suppressed spreading dogbane (>60%), and dicamba spot sprays were over 80% effective. Glyphosate spot sprays worked better than hand pulling, and wiping with glyphosate was also effective (Wu and Boyd, 2012). In an early experiment from the 1940s, dogbane was partially susceptible to 2,4 D (Egler 1947). In a forest setting, aerial application of glyphosate did not control spreading dogbane (Pitt et al 2000).
References
New York Flora Atlas: http://newyork.plantatlas.usf.edu/Plant.aspx?id=123
Native Plant Trust’s Go Botany online plant key: https://gobotany.nativeplanttrust.org/species/apocynum/androsaemifolium/?pile=non-alternate-remaining-non-monocots
USDA Plants Database: spreading dogbane page. https://plants.usda.gov/core/profile?symbol=APAN2.
University of Maryland Extension Toxic Plant Profile: Milkweed and Dogbane: https://extension.umd.edu/learn/toxic-plant-profile-milkweed-and-dogbane
Ohio State University Perennial and Biennial Weed Guide: Hemp Dogbane. https://www.oardc.ohio-state.edu/weedguide/single_weed.php?id=40
Fire Effects Information Systems entry for spreading dogbane: https://www.fs.fed.us/database/feis/plants/forb/apoand/all.html#125 .
Lin Wu and Nathan S. Boyd. 2012. Management of Spreading Dogbane (Apocynum androsaemifolium) in Wild Blueberry Fields. Weed Technology 26(4)777-782.
Frank E. Egler. 1947. 2,4-D Effects in Connecticut Vegetation, Ecology 29(3)382-386.
Frank E. Egler. 1949. Herbicide Effects in Connecticut Vegetation, Ecology 30(2)113-270.
Douglas G. Pitt et al. 2000. Five Years of Vegetation Succession Following Vegetation Management Treatments in a Jack Pine Ecosystem. Northern Journal of Applied Forestry 17(3) 100–109.