HPIPM:Field pennycress

Taxonomy

Domain	Eukarya
Kingdom	Plantae
Phylum	Magnoliophyta
Class	Magnoliopsida
Superorder	Rosanae
Order	Brassicales
Family	Brassicaceae
Genus	Thlaspi

Scientific Name

Thlaspi arvense

Common Name

field pennycress

Field pennycress (Thlaspi arvense L.)

Compiled by Melissa Graves, and Evette Allison, Montana State University, from the following sources:

http://plants.usda.gov/java/profile?symbol=THAR5

http://www.illinoiswildflowers.info/weeds/plants/pennycress.htm

http://www.co.stevens.wa.us/weedboard/other%20weeds/HTM%20pages/field%20pennycress.htm

http://www.agroatlas.ru/en/content/weeds/Thlaspi_arvense/

Identification and Life Cycle

Field pennycress may occur as either a winter or summer annual. It is from 1–2½' tall and will occasionally branch. Plants occurring as winter annuals form a rosette of leaves up to 6" across. Leaves are oblanceolate or obovate with long petioles. Summer annuals develop a central stem with several side stems. Stems are glabrous, ribbed, and may be winged along the ribs. The alternate leaves are up to 4" long and 1" across. They are lanceolate, oblanceolate, or narrowly ovate. The leaf margins are slightly wavy and sometimes have a few blunt teeth. Leaf surfaces are typically hairless. The lower leaves may have short petioles or may be sessile. The middle and upper leaves clasp the stem with a pair of ear-like lobes that taper to a blunt point. The small, white flowers of field pennycress are found in erect, terminal racemes. Blooming begins near the apex of the racemes, which lengthen to about 3-6" as they mature. The flowers are tiny, only about 1/8" across when fully open, with 4 white petals and 4 green sepals. Each flower has a slender pedicel up to ½" long. Blooming usually begins in late spring and continues through mid-summer. This period may last 1-2 months for a colony of plants. Some of the summer annual plants may bloom later in the year. While the flowers have very little scent, the foliage may have a mustard-garlic aroma. Each flower produces a single seedpod, called a silicle, up to ½" long and ½” across that is nearly circular. The seedpods have 2 cells, each containing several seeds, surrounded by a wide membranous wing. Another identifying characteristic is the small notch located at the top of each seedpod. The seeds are dark brown and oval-shaped, but well-rounded on one end and tapering to a point on the other. The seed surface is covered with curved concentric ridges resembling the patterns of a fingerprint. The root system consists of a taproot. Plants spread by reseeding, with no vegetative reproduction occurring.

Habitats

Field pennycress is a common agricultural weed, typically found in cropland, fallow fields, areas along roadsides and railroads, gardens and nursery plots, weedy meadows, and waste areas. This plant prefers disturbed areas, and does not normally invade higher quality natural habitats.

Biology and Ecology

Plants produce flowers from June to August. Fruit production usually begins in July and continues through September. Seed production ranges from 1,600 to 15,000 seeds per plant, with older winter seedlings producing higher quantities of seeds. Seed ripening begins before harvest and upon shattering infest soil for the next year. Seeds germinate easily and can maintain their ability to germinate as long as 20 years in the soil. A 6 year viability period is more typically seen with this species. If found in pasture and rangeland habitat, up to 37% of field pennycress seeds remain viable after passing through the digestive system of animals. Over-wintering and breaking dormancy increases seed germination. Optimum temperature of seed germination is 20-24°C (68-75 °F) while needing a minimum of 2 -4°C (36-39 °F).

Biological Control

There are currently no biological controls available for field pennycress.

Mechanical and Cultural Control

Field pennycress can occur in all soil types, but appears to prefer moist places. Hand-pulling and disposal of plants is an effective method of control with this weed. Carefully digging individual plants can manage the population, but may also carry weed seed to the soil surface and encourage additional germination. Mowing or tilling prior to seed production will control this plant but timing is essential because it produces seed much earlier than crops are harvested. In a turf situation, regular mowing at the proper height for the existing grass species can minimize weed growth and invasion.

Chemical Control

There is known resistance to ALS herbicides, group 2, in Canada. See this link for more information on resistance in field pennycress. http://www.weedscience.org/Case/Case.asp?ResistID=5097#SimilarCases

In the table below are some examples of herbicides that can be used to manage field pennycress

Consult and follow all herbicide labels for additional rate, application, crop restriction, and safety information. Additional herbicide information can be found at http://www.greenbook.net.

Herbicide Active Ingredient(s) Trade Name	Mode of Action	Product per Acre	Application Time or Growth Stage
Spring Wheat, Barley, and Oats
fluroxypyr, bromoxynil	Group 4 (synthetic auxins), Group 20 (inhibition of cellulose production)
*Starane NXT		14 fl oz / A.	Apply to the crop at the 3-leaf growth stage, up to flag leaf emergence. Apply to the weeds up to 8-leaf stage or 4" in height or when weeds are at a 2" rosette.
Spring, Winter and Durum Wheat
florasulam, fluroxypyr 1-methylheptyl ester, pyroxsulam	Group 2 (ALS inhibitor), Group 3 (microtubule inhibitor) and Group 4 (synthetic auxins)
*Goldsky		1 pt./A	Apply when wheat is at the 3-leaf to jointing stage and weeds are larger than 2" tall or 2" in diameter.
Oil Seed Crops
glyphosate		Group 9 (EPSP synthase inhibitors)
*Duramax		12 oz/A, 18 oz./A	Apply lower rate when weeds are 6" tall or less, higher rate when weeds are 6-12".
Corn (All types)
Diglycolamine salt of 3,6-dichloro-o-anisic acid	Group 4: synthetic auxins
*Clarity		16 oz/A or 8 oz/A	For early post emergence of the crop apply at the higher rate, before corn reaches the 5-leaf stage or 8".Apply the lower rate when corn is 8-36" tall.
Soybeans
Diglycolamine salt of 3,6-dichloro-o-anisic acid	Group 4: synthetic auxins
*Clarity		4-16 oz/A	For preplant control of weeds in soy prior to planting. Need a minimum of 1" rainfall or irrigation after application and a waiting period of 14-28 days before planting.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. Updated Nov 2008

References

For more images please visit IPM Images: http://www.ipmimages.org/search/action.cfm?q=field%20pennycress&Start=1&results=52