Corn speedwell

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This species can be found growing in moist or dry soils, in full sun or shade, and where turf is thin. It often grows in large, dense patches and is conspicuous during spring and early summer.

Life Cycle

Corn speedwell (Veronica arvensis L.) is a member of the plantain family (Plantaginaceae) and has a winter annual life cycle. Plants produce vegetative growth and flowers from early spring through summer. This weed reproduces via seeds, which germinate during cool, moist conditions in late summer, fall, or spring.

Identification

Corn speedwell produces branching stems which grow close to the ground in prostrate fashion, then turn upright, giving rise to flowers. Leaves are arranged opposite to one another on lower stems and form clusters on elevated stems. Individual leaves on lower stems are approximately ½- to ¾-inch long, mostly oval, with serrated margins. Leaves on elevated stems are shorter and narrower than lower leaves, generally do not have serrated margins, and are pointed at the tip. All leaf and stem surfaces are hairy.

Single flowers develop in leaf axils near the tips of elevated stems. Flowers are small, ¼- to ½-inch across, with blue petals and dark blue stripes. As with other speedwell species, each flower has two stamens and a single style. Fruits are heart-shaped, hairy, and contain yellow seeds.

Corn speedwell stem and leaves — Figure 2. Leaves of corn speedwell are hairy, oval, and opposite one another on lower stems. Leaves on the upper portion of elevated stems are narrow, hairy, with pointed tips. Photo by Peter Landschoot, Penn State

Corn speedwell flowers — Figure 3. Flowers of corn speedwell arising from leaf axils. Photo by Peter Landschoot, Penn State

Management and Control

Prevalence of corn speedwell can be reduced by increasing turf density through nitrogen fertilization, regular mowing, and the use of turfgrasses well-adapted to site conditions. This weed can be suppressed or controlled with various preemergence and postemergence herbicides.

Table 1. Some preemergence herbicide products labeled for control of corn speedwell.
Active ingredients	Product name(s)*
dithiopyr	Dimension 2EW, Dithiopyr 40WSB
pendimethalin	Lesco Pre-M AquaCap, Lesco Pre-M 3.3 EC, Pendulum 3.3 EC
prodiamine and quinclorac	Cavalcade PQ
sulfentrazone and prodiamine	Echelon 4SC

*Follow label precautionary statements, restrictions, and directions regarding tolerant turfgrass species, rates, and timing of applications. Active ingredients and products in bold type contain a specific reference to corn speedwell on the label. Other labels list speedwell but do not specify the individual species.

Table 2. Some postemergence herbicide products labeled for control of corn speedwell.
Active ingredients	Product name(s)*
2,4-D	Clean Amine, Hardball, Weedar 64, WEEDestroy AM-40, others
2,4-D, 2,4-DP, and dicamba	Super Trimec, Brushmaster (ester formulations)
2,4-D, clopyralid, and dicamba	Millennium Ultra 2**
2,4-D, fluroxypyr, and dicamba	Escalade 2
2,4-D, fluroxypyr, triclopyr, and flumioxazin	Sure Power (ester formulation)
2,4-D, MCPP, dicamba	Trimec Classic, Threesome, Lesco Three-Way, 3-D
2,4-D, quinclorac, and dicamba	Quincept; 2DQ Herbicide; Triad QC Select
2,4-D and triclopyr	Chaser (ester formulation)
2,4-D and triclopyr	Chaser 2 Amine, Turflon II Amine
2,4-D, triclopyr, and fluroxypyr	Momentum FX2
2,4-D, triclopyr, fluroxypyr, and sulfentrazone	Momentum 4-Score
2,4-D, triclopyr, dicamba, and pyraflufen-ethyl	4-Speed XT (ester formulation)
2,4-D, triclopyr, dicamba, and sulfentrazone	Foundation
amicarbizone	Xonerate 2SC
carfentrazone-ethyl	Quicksilver
carfentrazone-ethyl and quinclorac	SquareOne
fluroxypyr and triclopyr	Tailspin
MCPA, fluroxypyr, and dicamba	Change Up
MCPA, fluroxypyr, and triclopyr	Battleship III
MCPA, MCPP, and dicamba	Trimec Encore, Tri-Power
MCPA, MCPP, dicamba, and carfentrazone	PowerZone
MCPA, triclopyr, and dicamba	Cool Power, Lesco Three-Way Ester II (ester formulations)
MCPA, triclopyr, and dicamba	Lesco Eliminate, Horsepower
sulfentrazone	Surepyc
sulfentrazone and carfentrazone-ethyl	Dismiss NXT
sulfentrazone and quinclorac	Solitare, Solitare WSL
triclopyr and sulfentrazone	Tzone SE

*Follow label precautionary statements, restrictions, and directions regarding tolerant turfgrass species, rates, and timing of applications. Active ingredients and products in bold type contain a specific reference to corn speedwell on the label. Other labels list speedwell but do not specify the individual species.

**Clopyralid-containing products should not be used on residential lawns but can be used for treating weeds in non-residential turf.

References

Muenscher, W.C., 1987. Weeds 2nd ed. Cornell Univ. Press. 397 pp.
Uva, R.H., J.C. Neal, and J.M. DiThomaso. 1997. Weeds of the Northeast. Cornell Univ. Press. 397 pp.

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