Oldfield Toadflax

Description

Oldfield toadflax is also known as common or blue toadflax. It is a winter annual or biennial weed that is commonly found blooming in the spring in fields and roadsides. Oldfield toadflax is most often found in the Piedmont and Coastal Plain of North Carolina. The plant can flower from early spring (most common) to late fall (less common) - depending on growing conditions. The small blue flowers have three lobes and basal spurs. The leaves are small, bright green and linear. Small clumps of leaves will form in early spring, and the blue flowers will appear on long green stems shortly thereafter.

Cultural Control

Proper turf management is important for biennial broadleaf weed control. Maintain a dense, actively growing turf through proper mowing, fertilizing, and watering practices. Mow at the proper height for your selected adapted turfgrass. Coring and traffic control reduce compaction and encourage desirable turfgrass competition. It is best to control this biennial broadleaf weed in spring or fall, if actively growing at these times.

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) 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 (4 SC) (Echelon) 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.​

Species Data

Oldfield toadflax growth habit.Figure 1. Oldfield toadflax growth habit.Oldfield toadflax growth habit.Figure 2. Oldfield toadflax growth habit.Oldfield toadflax growth habit.Figure 3. Oldfield toadflax growth habit.Oldfield toadflax growth habit.Figure 4. Oldfield toadflax growth habit.Oldfield toadflax growth habit.Figure 5. Oldfield toadflax growth habit.Oldfield toadflax growth habit.Figure 6. Oldfield toadflax growth habit.Oldfield toadflax leaf width.Figure 7. Oldfield toadflax leaf width.Oldfield toadflax flower color.Figure 8. Oldfield toadflax flower color.Oldfield toadflax flower color.Figure 9. Oldfield toadflax flower color.Oldfield toadflax flower color.Figure 10. Oldfield toadflax flower color.Oldfield toadflax flower color.Figure 11. Oldfield toadflax flower color.Oldfield toadflax flower color.Figure 12. Oldfield toadflax flower color.

Written By

Photo of Dr. Charles PeacockDr. Charles PeacockProfessor and Extension Turfgrass Specialist (919) 515-7615 charles_peacock@ncsu.eduCrop and Soil Sciences - NC State University
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This Extension factsheet can also be viewed at:
https://content.ces.ncsu.edu/oldfield-toadflax