Scouting for weeds: Hairy bittercress
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Editor’s note: The identification information is from the new field guide An IPM Pocket Guide for Weed Identification in Nurseries and Landscapes. For ordering information, call 517-353-6740 or visit: http://www.ipm.msu.edu/pdf/pocketGuidesLandsc07.pdf
Hairy bittercress (Cardamine hirsuta L.) (view images)
Family. Brassicaceae (Mustard)
Life cycle. Rapidly growing winter or summer annual.
Leaves. Round cotyledons on long petioles are followed by heart- to kidney-shaped first two true leaves. Subsequent leaves are compound with two to eight alternately arranged leaflets and larger terminal leaflet. Leaflet margins are shallowly toothed to lobed. Mostly hairy leaves initially develop from a basal rosette, followed by a few smaller, narrow stem leaves. Basal leaves are persistent through maturity.
Stems. Mostly erect, smooth, angled stems branch mainly at the base. Stems are less than 12 inches tall.
Flowers and fruit. Very small, white flowers with four petals are arranged in terminal clusters. Fruit are very narrow, about 1-inch-long, flattened, upward-pointing capsules that explosively eject numerous small seeds.
Reproduction. Seeds. Multiple generations may be produced in a single year.
Smallflowered bittercress: Cardamine parviflora L.
Differs by having up to six leaflet pairs and basal leaves that are not present at maturity.
Hairy bitttercress is one of the most troublesome weeds in nursery production. It is a prolific seed producer with a short life cycle (three to four weeks) that is capable of ejecting seeds several feet from the main plant with specialized fruit capsules. Cultural options include sanitation, mulching, subirrigation and large-porous media. The best option is the use of preemergence herbicides to control the ungerminated seeds in the soil. These options include granular formulations of OH2, Regal O-O, Rout, Ronstar, Surflan, Showcase, XL and SnapShot.