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diffuse knapweed (Centaurea diffusa (Lam.) ) Chemical Control

GROWTH HABIT: Annual or biennial, bushy, up to 2 ft., tall. Rosette formed first year, flowering stalk elongates second year.
LEAVES: Greyish-green, alternate, basal leaves whorled, upper leaves much reduced. Covered with fine hair.
STEM: Hairy, erect, single main stem from a rootstock, branched near or above the base.
FLOWER: Solitary, usually white, sometimes pink, rose or lavender; seedhead bracts end as sharp, rigid spines.
ROOTS: Elongated taproot.
SEEDS: Oblong, dark brown or grey with longitudinal lines.
USEFUL HERBICIDES:

Herbicide Brand How to Apply When to Apply Comments

2,4-D spray in late fall or early spring do not let dairy animals graze within 7 days of application

Tordon spray when perennial weeds have fully developed, green leaves rain within 6 hours of application may cause poor results

Arsenal

Curtail spray 1 to 4 leaf stage within 6 hours will reduce control

Stinger

Further information about these herbicides:

Herbicide Brand Active Ingredient Mode of Action Comments

2,4-D MCPA systemic abnormal growth in 2-10 days

Tordon peloram systemic works with cell division, causing leaf cupping, and eventual death

Arsenal imazapyr

Curtail premix systemic abnormal growth in 2-10 days

Stinger clopyralid

By: Nichole Near May 25, 2002
Recommendations By Weed mtwow.org HOME

Herbicide Brand	How to Apply	When to Apply	Comments
2,4-D	spray	in late fall or early spring	do not let dairy animals graze within 7 days of application
Tordon	spray	when perennial weeds have fully developed, green leaves	rain within 6 hours of application may cause poor results
Arsenal
Curtail	spray	1 to 4 leaf stage	within 6 hours will reduce control
Stinger

Herbicide Brand	Active Ingredient	Mode of Action	Comments
2,4-D	MCPA	systemic	abnormal growth in 2-10 days
Tordon	peloram	systemic	works with cell division, causing leaf cupping, and eventual death
Arsenal	imazapyr
Curtail	premix	systemic	abnormal growth in 2-10 days
Stinger	clopyralid