Distinguishing Mustard Varieties

Early Plants

Early plants can be typically be identified according to their cotyledon, first true leaves, and/or the stem. 

Mature Plants

Non-flowering/Basal rosette

Flowering plants

References

Uva R H, Neal J C, DiTomaso J M. 1997. Weeds of the Northeast. Book published by Cornell University, Ithaca NY. The go-to for weed ID in the Northeast; look for a new edition sometime in 2019.

Cornell University’s Turfgrass and Landscape Weed ID app. Identification and control options for weeds common to turf, agriculture, and gardens in New York; uses a very simple decision tree to identify your weed.

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.

Mid-June 2020

CCE Field Crops Specialist Mike Stanyard ran across this weed in winter triticale. It appeared to have been seeded with the triticale, as it was only growing in the row, as tall as the heading out triticale. Scott Morris of the Cornell Weed Ecology and Management lab identified it as common corncockle (Agrostemma githago), a common weed seed contaminant in grain crops. Identifying traits include narrow, opposite leaves with long hairs, and single, purple five-petaled flowers which bloom at the top of a long stalk over the summer. Common corncockle is mildly toxic to humans and livestock when ingested.

This was historically a significant weed of European grain crops, but largely disappeared from its native range due to the advent of herbicides, improvements to seed cleaning technology, and the shift to winter wheat. Herbicide resistance to 2,4-D and MCPA is mentioned in an article from the 1980s on corn cockle competition from eastern Oregon, but the species is not listed in the International Database of Herbicide Resistant Weeds maintained by the Weed Science Society of America. It is listed as a noxious weed in Arkansas and as a plant pest in South Carolina. Common corncockle is also used as a garden plant. 

References:

Bugwood.org’s listing for corn cockle: https://www.invasive.org/browse/subinfo.cfm?sub=5049

Wikipedia entry for corn cockle (also corn-cockle, corncockle): https://en.wikipedia.org/wiki/Agrostemma_githago

WSSA International Herbicide-Resistant Weed Database: http://www.weedscience.org/Pages/Species.aspx

Rycrych, DJ 1981. Corn Cockle (Agrostemma githago) competition in winter wheat (Triticum aestivum). Weed Science 29(3) pp. 360-363.

North Carolina Extension Gardener Plant Toolbox: Agrostemma githago: https://plants.ces.ncsu.edu/plants/agrostemma-githago/

USDA PLANTS Database file for common corncockle: https://plants.usda.gov/core/profile?symbol=AGGI

Having a hard time telling these small plants apart? Us too! But this is often the stage when ID is most helpful. In the spring, a lot of plants are in rosette form, a clump of vegetation with no stalk. How to tell what’s in your field now, when you are planning weed management?

We’ve added a page just for this problem: Rosette Forming Weeds of Early Spring. We hope it will help you sort out your spring weeds. For assistance with management of the various species, please see Cornell’s crop and pest management guides and the references listed in the page.

PS – the photos above, starting from the left, are: horseweed, shepherd’s purse, Canada goldenrod, Virginia pepperweed, and common mullein. All photos by the Ohio State Weed Lab of Ohio Sate University except for shepherd’s purse (Steve Dewey of the Utah State University), Canada goldenrod (Michigan State University), and Virginia pepperweed (Joseph DiTomaso of the University of California at Davis). All photos available on bugwood.org.