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Spiny Sowthistle

Description

Spiny sowthistle is a summer annual weed with a basal rosette and an upright flowering stem. The leaves are deeply notched and wavy. Spiny sowthistle has yellow flowers that appear in late spring, and the leaves and stems emit a milky-white latex when crushed. The weed is found in open habitats that include waste areas, turf, and roadsides.

Cultural 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 summer annual broadleaf weed in late spring or early summer because it is easier to control at this time and the turf will have a greater chance of recovering the areas previously occupied by weeds.

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

Herbicide and Formulation

mesotrione, MOA 27 (Tenacity) 4 SC

Amount of Formulation per 1,000 sq ft

0.092 to 0.183 fl oz

Amount of Formulation per Acre

4 to 8 fl oz

Pounds Active Ingredient per Acre

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 Barricade 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.

Preemergence and Postemergence Control

Herbicide and Formulation

sulfentrazone + prodiamine, MOA 14 + 3 (Echelon 4 SC) 4 SC

Amount of Formulation per 1,000 sq ft

0.184 to 0.826 fl oz

Amount of Formulation per Acre

0.5 to 2.25 pt

Pounds Active Ingredient per Acre

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 inches 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. Echelon should not be applied to cool-season turf with N-containing fertilizers unless some short-term discoloration is tolerable.

Presentations

Publications

Species Data

Growth Season/Life Cycle

summer annual weed

Growth Habit

upright; young plant is a basal rosette, older plant is upright

autopsy
autopsy
autopsy
leafarrangement
leafarrangement
leafarrangement
Leaflet Number

one

Leaf Margin

lobed

claspingleaf
claspingleaf
claspingleaf
leafarrangement
leafarrangement
leafarrangement
sowthistle
sowthistle
sowthistle
sowthistle2
sowthistle2
sowthistle2
Leaf Hairs

generally, leaves are hairless but have sharp prickles on leaf margins

claspingleaf
claspingleaf
claspingleaf
sowthistle
sowthistle
sowthistle
sowthistle2
sowthistle2
sowthistle2
Leaf/Leaflet Shape

oval/egg-shaped/elliptical; note the clasping lobes at the base of leaves

claspingleaf
claspingleaf
claspingleaf
sowthistle
sowthistle
sowthistle
sowthistle2
sowthistle2
sowthistle2
Leaf Width

1/2 - 1 inch

claspingleaf
claspingleaf
claspingleaf
sowthistle
sowthistle
sowthistle
sowthistle2
sowthistle2
sowthistle2
Leaf Venation

pinnate

claspingleaf
claspingleaf
claspingleaf
sowthistle
sowthistle
sowthistle
sowthistle2
sowthistle2
sowthistle2
Leaf Arrangement

alternate

autopsy
autopsy
autopsy
claspingleaf
claspingleaf
claspingleaf
leafarrangement
leafarrangement
leafarrangement
sowthistle
sowthistle
sowthistle
sowthistle2
sowthistle2
sowthistle2
sowthistle3
sowthistle3
sowthistle3
Root Type

taproot

autopsy
autopsy
autopsy
rootsystem
rootsystem
rootsystem
Flower Color

yellow

autopsy
autopsy
autopsy
leafarrangement
leafarrangement
leafarrangement