Johnsongrass (Sorghum halepense)

fenoxaprop (Acclaim or Horizon)

Rate 0.15 to 0.25 lb ai/a

Time Apply to actively growing seedlings with two to five leaves. Larger plants are more difficult to control. Apply to rhizome Johnsongrass that is 24 to 60 inches tall and growing actively.

Remarks Rhizome Johnsongrass is only suppressed. Do not apply within 3 weeks after mowing.

Caution Do not use a crop oil or surfactant.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Aryloxyphenoxy propionate

fluazifop (Fusilade DX)

Rate 0.25 to 0.375 lb ai/a (2 to 3 pints/a)

Time Apply to actively growing Johnsongrass 8 to 18 inches tall but before boot stage.

Remarks Apply with 1% v/v crop oil concentrate or 0.25% v/v nonionic surfactant. Fluazifop acts very slowly, taking at least 2 weeks and often 4 weeks to show effectiveness. Do not apply to stressed grasses. If weed regrows, repeat application at 0.187 to 0.375 lb ai/a.

Caution Do not use crop oil concentrate if treating Johnsongrass in ornamentals. Do not apply if rain is expected within 1 hour.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Aryloxyphenoxy propionate

glyphosate

Rate 2.25 lb ae/a

Time Apply at heading time to actively growing plants.

Remarks Rain within 6 hr after application may reduce effectiveness. Spray to cover but not to point of runoff.

Caution Glyphosate controls other grasses and vegetation in treated areas.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

imazapic (Plateau)

Rate 0.188 lb ae/a

Time Apply postemergence, at the late-boot or bloom stage.

Remarks Use a methylated seed oil at 1 quart/a; do not exceed 25 gal/a spray volume.

Caution Before using, note crop rotation restrictions.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Imidazolinone

imazapic + glyphosate (Journey)

Rate 21 to 32 oz/a

Time Apply postemergence to grass when it is 18 to 24 inches at the whorl.

Remarks Add a suitable surfactant to the spray mix. See label for details.

Caution Before using, note crop rotation restrictions.

Site of action (imazapic) Group 2: acetolactate synthase (ALS) inhibitor; (glyphosate) Group 9: inhibits EPSP synthase

Chemical family (imazapic) imidazolinone; (glyphosate) none generally accepted

MSMA (Bueno or Trans-Vert)

Rate 2.25 lb ai/a

Time This herbicide is foliar-active; apply to rapidly growing foliage.

Remarks Use with caution on or near ornamentals (see label). Can mix with 2,4-D for broader control on non-cropland. MSMA is inactivated by soil surface adsorpintsion.

Caution Keep liquid or dust away from eyes. Wash eyes immediately with water if exposed.

Site of action Group 17: not well understood

Chemical family Organoarsenical

sethoxydim (Poast)

Rate 0.28 to 0.47 lb ai/a (1.5 to 2.5 pints/a)

Time Apply to actively growing Johnsongrass when the plant is 15 to 25 inches tall.

Remarks Apply with 2 pints/a crop oil concentrate. Sethoxydim acts very slowly, taking at least 2 week and often 4 week to show herbicide effectiveness. Do not apply to stressed grasses. If Johnsongrass regrows, repeat application when it is 6 to 8 inches tall.

Caution Do not apply if rain is expected within 1 hour.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Cyclohexanedione