NC State Extension Publications

Description

Corn speedwell is a small, weak, low-growing winter annual that thrives in thin open turf and often appears in solid stands. The lower leaves of corn speedwell are rounded and toothed, while the upper leaves are smaller and more pointed. Like the other speedwells, the leaves are both alternate (end of stem) and opposite (base of stem). Corn speedwell is similar in many respects to Persian and ivyleaf speedwell. However, it has the smallest leaves of the three species. Ivyleaf speedwell leaves are thicker and less serrated than those of either corn or Persian speedwell. The entire corn speedwell plant is covered with soft, fine hairs. The flowers are small, bright blue with white throats, and nearly stalkless, whereas those of Persian and ivyleaf speedwell have stalks that are longer than 1 mm. The seedpods are heart-shaped in all three species.

Cultural Control

Corn speedwell is a low-growing winter annual that thrives in thin open turf and often appears in solid stands. Winter annual broadleaf weeds germinate in the fall or winter and grow during any warm weather, which may occur in the winter, but otherwise remain somewhat dormant during the winter. They resume growth and produce seed in the spring and die as temperatures increase in late spring and early summer. They quickly invade thin turf areas especially where there is good soil moisture. Shade may also encourage growth. A dense, vigorous turf is the best way to reduce the encroachment of this weed. First, select adapted turfgrass cultivars for your area and then properly fertilize, mow, and water to encourage dense growth. Corn speedwell is similar in appearance to Persian and ivyleaf speedwell.

Chemical Control


Herbicide and Formulation Amount of Formulation per 1,000 sq ft Amount of Formulation per Acre Pounds Active Ingredient per Acre
Preemergence and Postemergence Control
mesotrione, MOA 27 (4 SC) (Tenacity) 0.092 to 0.183 fl oz 4 to 8 fl oz 0.125 to 0.25
Precaution and Remarks: Use on residential turf, golf courses (not greens) and sod farms for pre- and postemergence weed control. Tolerant turfgrasses include St. Augustinegrass, centipedegrass, tall fescue, fine fescue, Kentucky bluegrass, and perennial ryegrass. Add a nonionic surfactant and repeat application after 2 to 3 weeks for improved postemergence control. Tank mix with prodiamine 65 WG for extended preemergence grassy weed control. Can be applied at seeding to all tolerant grasses except fine fescue. After turf germination, wait 4 weeks or until turf has been mowed twice before making a postemergence application. Also controls henbit, chickweed, dandelion, white clover, Florida betony, Florida pusley, ground ivy, oxalis, wild violet, creeping bentgrass, and yellow nutsedge.​
[sulfentrazone + prodiamine], MOA 14 + 3 (Echelon 4 SC) 4 SC 0.184 to 0.826 fl oz 0.5 to 2.25 pt 0.25 to 1.125
Precaution and Remarks: For use in residential and institutional lawns, athletic fields, sod farms, golf course fairways and roughs, roadsides, utility right-of-ways, railways, and industrial areas. Apply to turf following a second mowing if a good root system has been established. Apply up to 12 fluid ounces per acre to bentgrass at 0.5 inch or higher, fine fescue, and perennial ryegrass. Apply 18 to 24 fluid ounces per acre to perennial bluegrass, tall fescue, and all warm season grasses except St. Augustinegrass (do not apply) and bermudagrass (apply 18 to 36 fluid ounces per acre). For sod production, apply 6 months after establishment, and do not harvest within 3 months. Do not apply with adjuvants or surfactants. [Sulfentrazone + prodiamine should not be applied to cool-season turf with N-containing fertilizers unless some short-term discoloration is tolerable.​
Postemergence Control
[thiencarbazone-methyl + iodosulfuron + dicamba], MOA 14 + 2 + 4 (68 WG) (Celsius WG) 0.057 to 0.113 oz 2.5 to 4.9 oz 0.106 to 0.208
Precaution and Remarks: For use by licensed applicators in residential and commercial lawns, golf courses (excluding greens), sports fields, parks, recreational areas, roadsides, school grounds, and sod farms. Provides up to 60 days residual control. Use on bermudagrass, zoysiagrass, centipedegrass, and St Augustinegrass. Apply maximum 7.4 ounces per acre per season. Safe to use at high temperatures. Ryegrass can be overseeded 2 weeks after application. Apply 30 days prior to seeding bermudagrass or zoysiagrass. Wait 2 weeks after bermudagrass seedlling emergence or sprigging operation before applying. For zoysiagrass, wait 3 weeks after seedling emergence before applying. A nonionic surfactant or methylated seed oil at 0.25% v/v is required for optimum control.​
[thiencarbazone-methyl + foramsulfuron + halosulfuron], MOA 14 + 2 + 2 (60.5 WG) (Tribute Total) 0.0735 oz 3.2 oz 0.121
Precaution and Remarks: Apply to well-established residential and commercial bermudagrass and zoysiagrass (Emerald, Meyer, Zeon) lawns, golf courses (excluding greens), athletic fields, sod farms, roadsides, parks, cemeteries and recreational areas. Do not exceed 3.2 ounces per acre per application or 6.4 ounces per acre yearly. Use 0.25 to 0.5% by volume nonionic surfactant or 0.5 to 1% by volume methylated seed oil. After application, wait 12 weeks to overseed ryegrass or bermudagrass. Wait 1 month after bermudagrass seedling emergence and 2 weeks after sprigging or sodding bermudagrass before treating. Temporary stunting and yellowing may last up to 2 weeks but turf will recover. Crabgrass and goosegrass are controlled up to 2 tiller stage.
clopyralid, MOA 4 (3 EC) (Lontrel T&O) 0.1 to 0.5 fl oz 0.25 to 1.33 pt 0.09 to 0.5
Precaution and Remarks: Do not apply to home lawns. May be used on bentgrass, Kentucky bluegrass, creeping, red, chewings, sheep and tall fescue, perennial ryegrass, bermudagrass, bahiagrass, buffalograss, centipedegrass, zoysiagrass, and St. Augustinegrass. Do not apply to putting greens and tees. Should be applied in a minimum of 20 gallons of water per acre. Surfactants are not necessary. Do not apply to exposed roots of certain trees and shrubs (legumes such as acacia, locust, mimosa, redbud, or mesquite) or Tilia spp. Do not use treated clippings for mulching and compost during the growing season of application.​
carfentrazone-ethyl, MOA 14 (1.9 EW) (various brands) 0.0126 to 0.048 fl oz 0.55 to 2.1 fl oz 0.008 to 0.031
Precaution and Remarks: May be applied to bahiagrass, bermudagrass, buffalograss, centipedegrass, St. Augustinegrass, zoysiagrass, Kentucky bluegrass, tall fescue, fine fescue, perennial ryegrass, and bentgrass. To expand the weed spectrum and extend control of the weeds listed here and on the label, carfentrazone-ethyl can be tank mixed with the entire range of phenoxy products—amines, esters, and other salts—and is also compatible with dicamba, atrazine, glyphosate, glufosinate, clopyralid, triclopyr, and MSMA. When applied alone, add 0.12 to 0.25% nonionic surfactant.​
[carfentrazone + 2,4-D ester + MCPP + dicamba], MOA 14 + 4 + 4 + 4 (2.2 EC) (Speed Zone) 0.75 to 1.8 fl oz 2 to 5 pt 0.55 to 1.375
Precaution and Remarks: May be used on annual and perennial bluegrass, annual and perennial ryegrass, tall and fine fescue, creeping and colonial bentgrass, common and hybrid bermudagrass, and zoysiagrass. For use in ornamental turf, golf courses, lawns, sod farms, cemeteries, and parks. Optimum results when applied when temperatures are between 45 and 75 degrees F but may be applied up to 90 degrees F. Lower rates may be used in cooler weather. Rainfast within 3 hr and may reseed after 2 week. May apply 3 to 4 wk after sodding, sprigging, or plugging. Also may be used on bahiagrass, buffalograss, St. Augustinegrass, centipedegrass, seashore paspalum, and kikuyugrass. May reseed after 1 week.​
[carfentrazone + 2,4-D ester + MCPP + dicamba], MOA 14 + 4 + 4 + 4 (0.81 EC) (Speed Zone Southern) 0.55 to 2.2 fl oz 1.5 to 6 pt 0.1519 to 0.6075
Precaution and Remarks: May be used on annual and perennial bluegrass, annual and perennial ryegrass, tall and fine fescue, creeping and colonial bentgrass, common and hybrid bermudagrass, and zoysiagrass. For use in ornamental turf, golf courses, lawns, sod farms, cemeteries, and parks. Optimum results when applied when temperatures are between 45 and 75 degrees F but may be applied up to 90 degrees F. Lower rates may be used in cooler weather. Rainfast within 3 hr and may reseed after 2 week. May apply 3 to 4 wk after sodding, sprigging, or plugging. Also may be used on bahiagrass, buffalograss, St. Augustinegrass, centipedegrass, seashore paspalum, and kikuyugrass. May reseed after 1 week.​
[carfentrazone + MCPA ester + MCPP + dicamba], MOA 14 + 4 + 4 + 4 (2.91 EC) (Power Zone) 0.75 to 2.2 fl oz 2 to 6 pt 0.7275 to 2.1825
Precaution and Remarks: Same precautions and turf uses as [carfentrazone + 2,4-D ester + MCPP + dicamba] 2.2 EC except cannot be applied to creeping and colonial bentgrass.
penoxsulam + sulfentrazone + 2,4-D + dicamba (Avenue South) 1.0 to 2.2 fl oz 2.7 to 6 pt 0.271 to 0.602
Precaution and Remarks: May be used on established Kentucky bluegrass, annual bluegrass, perennial ryegrass, annual ryegrass, tall fescue, common and hybrid bermudagrass, zoysiagrass, centipedegrass, and seashore paspalum. Do not apply more than 2.7 pints per acre on fescue or perennial ryegrass unless turf injury can be tolerated. Do not apply more than 3.5 pints per acre on St. Augustinegrass unless injury, discoloration, stunting, and thinning can be tolerated.
[sulfentrazone + 2,4-D amine + MCPP + dicamba], MOA 14 + 4 + 4 + 4 (2.18 SL) (Surge) 0.92 to 1.84 fl oz 2.5 to 5 pt 0.68 to 1.36
Precaution and Remarks: Apply 2.5 to 3.25 pints per acre on warm season turf including bermudagrass species, zoysiagrass, bahiagrass, and buffalograss. Apply 3.25 to 4 pints per acre on cool season turf including species of bluegrass, ryegrass, fescue, and bentgrass (excluding greens and tees). 4 to 5 pints per acre needed to control corn speedwell and wild violet. Turf areas include residential, ornamental, institutional, and sod farms. Apply to grass seedlings after second mowing. Apply to sodded, sprigged, or plugged areas 3 to 4 weeks after operations. Treated areas may be reseeded 3 weeks after application.​
[triclopyr ester + sulfentrazone + 2,4-D ester + dicamba], MOA 4 + 14 + 4 + 4 (2.51 EC) (Tzone SE) 0.75 to 1.5 fl oz 2 to 4 pt 0.628 to 1.26
Precaution and Remarks: Apply 2 to 2.25 pints per acre on fully dormant bermudagrass, zoysiagrass, and bahiagrass. Apply 3.25 to 4 pints per acre on annual and perennial bluegrass and ryegrass, and tall, red, and fine fescue. Rainfast within 3 hours. Approved turf areas include residential, ornamental, institutional, noncropland, and sod farms. Apply to grass seedlings after the second or third mowing. Apply to sodded, sprigged, or plugged areas 3 to 4 weeks after operations. Treated areas may be reseeded 3 weeks after application.​

Species Data

  • GROWTH SEASON / LIFE CYCLE
    • winter annual weed
  • GROWTH HABIT
  • LEAFLET NUMBER
    • one
  • LEAF MARGIN
    • rounded teeth
  • LEAF HAIRS
    • upper/lower surface
  • LEAF / LEAFLET SHAPE
    • lower leaves egg-shaped or round, upper leaves linear
  • LEAF WIDTH
    • 12 - 1 inch
  • LEAF VENATION
    • palmate
  • LEAF ARRANGEMENT
    • lower leaves opposite, upper leaves alternate
  • ROOT TYPE
    • fibrous
  • FLOWER COLOR
    • blue / purple
Corn speedwell growth habit.

Figure 1. Corn speedwell growth habit.

Corn speedwell growth habit.

Figure 2. Corn speedwell growth habit.

Corn speedwell growth habit.

Figure 3. Corn speedwell growth habit.

Corn speedwell growth habit.

Figure 4. Corn speedwell growth habit.

Corn speedwell growth habit.

Figure 5. Corn speedwell growth habit.

Corn speedwell growth habit.

Figure 6. Corn speedwell growth habit.

Corn speedwell growth habit.

Figure 7. Corn speedwell growth habit.

Author

Professor and Extension Turfgrass Specialist
Crop and Soil Sciences

Publication date: Nov. 27, 2017

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