Nutsedge, yellow (Cyperus esculentus) and purple (Cyperus rotundus)

alachlor (Lasso or Micro-Tech)

Rate 1.5 to 4 lb ai/a

Time Use a preplant incorporation application.

Remarks Selective in corn and dry beans. Controls most annual grasses and certain annual broadleaf weeds. Absorbed mainly by germinating plant shoots; seems to inhibit protein synthesis.

Caution A restricted-use herbicide. Avoid contact with the eyes and skin.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Chloroacetamide

dichlobenil (Casoron)

Rate 150 lb/a of 4% granules

Time Apply in winter just before a period of rain, or in spring just before applying bark mulch in landscape plantings.

Remarks Incorporate by rototilling or rain. Selective in some fruits and ornamentals (see label). Apply midwinter immediately before a cold rain to reduce volatility and enhance weed suppression. Weigh and distribute uniformly exact quantities over precisely measured areas. Oregon results from over 9 years suggest perennial weeds can be suppressed with 4-, 3- and 2-lb ai/a rates applied in 3 consecutive years. Grazing livestock is prohibited. In non-crop-land areas only, up to 250 to 500 lb of 4% granules can be used for nutsedge control. Inhibits cellulose and cell wall formation.

Caution Do not breathe dust or allow contact with eyes or skin.

Site of action Group 20: inhibits cell wall synthesis Site A

Chemical family Nitrile

EPTC (Eptam)

Rate 3 to 6 lb ai/a

Time Apply before final seedbed preparation in the spring.

Remarks Incorporate immediately by disking in two directions, or rototill to distribute 2 to 3 inches deep. Apply only to soil dry on the surface, then disk immediately. Use before planting beans and potatoes. Treatment suppresses nutsedge for one season only.

Caution Incorporate 2 to 3 inches into soil immediately after application.

Site of action Group 8: lipid synthesis inhibitor but not an ACCase inhibitor

Chemical family Thiocarbamate

EPTC with safener (Eradicane or Genate) or butylate with safener (Sutan)

Rate 4 to 6.14 lb ai/a, depending on soil type and infestation; see label.

Time Apply preplant and incorporate immediately and thoroughly.

Remarks These herbicides are selective in corn. Perennial weeds must be turned under and chopped up thoroughly before treatment. See label for additional application and incorporation instructions. Suppresses emergence of new shoots from yellow nutsedge tubers but does not necessarily kill them.

Caution Do not use EPTC without safener on "Golden Jubilee" sweet corn west of the Cascades. Do not exceed 4 lb ai/a EPTC with safener on sweet corn.

Site of action (both) Group 8: lipid synthesis inhibitor but not an ACCase inhibitor

Chemical family (both) Thiocarbamate

glyphosate

Rate 2.25 lb ae/a as a broadcast spray, or a 1% solution using hand-held equipment

Time When nutsedge is actively growing in midseason but before new tubers begin to form, usually by June 15 to July 1.

Remarks Nutsedge can be reduced by encouraging active growth and applying glyphosate once or more often when several nutsedge leaves are present but before new tubers begin to form.

Caution Re-treatment is important. Glyphosate controls grasses as well as other vegetation in the treated area.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

halosulfuron (Permit, Sandea, or SedgeHammer)

Rate 0.5 to 1 oz ai/a (0.67 to 1.33 oz/a)

Time Labels differ. For example, apply SedgeHammer to yellow nutsedge in the three- to five-leaf stage. Apply SedgeHammer in turf to yellow nutsedge in the three- to eight-leaf stage of growth.

Remarks Halosulfuron is labeled on several crops. Consult labels for stage of crop or turf growth. Add 1 to 2 quarts nonionic surfactant or crop oil concentrate per 100 gal spray solution for broadcast applications. A second halosulfuron application may be required 6 to 10 weeks after the first.

Caution Do not exceed 1.5 oz ai/a (2 oz/a) of Permit or Sandea or two applications per season. Do not exceed 0.4 oz ai/a (5.33 oz/a) of SedgeHammer or four applications per season. Note labels for information on recropping, reseeding, and site of application.

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

Chemical family Sulfonylurea

imazapic (Plateau)

Rate 0.125 to 0.188 lb ai/a

Time Apply postemergence when plants have bolted.

Remarks Add 1 quart/a methylated seed oil; 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

S-metolachlor (Dual II Magnum or Dual Magnum)

Rate Refer to label

Time Use preplant incorporated.

Remarks Incorporate uniformly to 2 inches before planting. Use lower rates on coarse soils.

Caution May cause skin sensitization reactions in some people. Do not breathe spray mist.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Chloroacetamide