Under Asphalt

bromacil (Hyvar X)

Rate 4.8 to 12 lb ai/a

Time Apply immediately before paving to avoid lateral movement of the herbicide as a result of soil movement due to rain or mechanical activity.

Remarks Remove rhizomes, tubers, and other vegetative plant parts by scalping with a grader blade before application.

Caution Do not use under pavement in residential or recreational areas. Desirable plants may be injured if their roots extend into treated areas or if planted in treated areas.

Site of action Group 5: photosystem II inhibitor

Chemical family Uracil

bromacil + diuron (Krovar IDF)

Rate 17 to 30 lb product/a

Time Apply immediately before paving to avoid lateral movement of the herbicide as a result of soil movement due to rain or mechanical activity.

Remarks Before applying, use a grader blade to scalp and remove rhizomes, tubers, and other vegetative plant parts.

Caution Do not use under pavement in residential or recreational areas. Desirable plants may be injured if their roots extend into treated areas or if planted in treated areas.

Site of action (bromacil) Group 5: photosystem II inhibitor; (diuron) Group 7: photosystem II inhibitor

Chemical family (bromacil) uracil; (diuron) substituted urea

dichlobenil (Casoron or Barrier)

Rate 10 lb ai/a (Barrier or 12 lb ai/a (Casoron)

Time Apply after final grade is established.

Remarks Do not move soils after applying. Pave as soon as possible after applying. Forms a vapor barrier, preventing roots and shoots from penetrating. Reportedly, this product is safe to use near desirable vegetation. For resurfacing work, control existing weeds before applying dichlobenil.

Caution Herbicide will volatilize and be lost if not immediately covered by asphalt.

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

Chemical family Nitrile

imazapic (Plateau, Imazapic E 2SL)

Rate 0.1875 lb ai/a (12 oz/a product)

Time Apply to soil surface after final grade is established.

Remarks Incorporation improves control if soil is not moist at treatment. Incorporate imazapic 2 inches into soil using a rototiller or disc, or with 1 inch of rain or irrigation.

Caution Do not let treated soil wash or move into untreated area. Desirable plants may be injured if their roots extend into treated areas or if planted in treated areas.

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

Chemical family Imidazolinone

imazapyr (Arsenal)

Rate 1.5 lb ae/a

Time Apply after final grade is established.

Remarks Before applying, use a grader blade to scalp and remove rhizomes, tubers, and other vegetative plant parts. Apply in at least 100 gal/a water. Pave as soon as possible after application. If soil is not moist at application, use a rototiller or disc to incorporate 4 to 6 inches deep. Rain or 1 inch of irrigation also provides uniform incorporation. Use only in industrial sites or where the pavement has a suitable barrier along the perimeter to prevent root encroachment of desirable plants.

Caution Do not let treated soil wash or move into untreated areas. Desirable plants may be killed or injured if herbicide is applied where roots are or may extend. See label for areas where this product can be used.

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

Chemical family Imidazolinone

imazapyr + diuron (Sahara)

Rate 10 lb/a

Time Apply immediately before paving to avoid lateral movement of the herbicide as a result of soil movement due to rain or mechanical activity.

Remarks Before applying, use a grader blade to scalp and remove rhizomes, tubers, and other vegetative plant parts. If soil is not moist at application, incorporate herbicide mechanically. Use only in industrial sites or where pavement has a suitable barrier along the perimeter to prevent root encroachment of desirable plants.

Caution Do not use under pavement in residential or recreational areas. Desirable plants may be injured if their roots extend into treated areas or if planted in treated areas.

Site of action (imazapyr) Group 2: acetolactate synthase (ALS) inhibitor; (diuron) Group 7: photosystem II inhibitor

Chemical family (imazapyr) imidazolinone; (diuron) substituted urea

pendimethalin (Pendulum 3.3EC)

Rate 2 to 4 lb ai/a (2.4 to 4.8 quarts/a)

Time Apply after final grade is established.

Remarks Remove rhizomes, tubers, and other vegetative plant parts by scalping with a grader blade before application.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

prometon (Pramitol 25E)

Rate 7.5 to 10 gal/a

Time Apply after final grade is established.

Remarks Remove rhizomes, tubers, and other vegetative plant parts by scalping with a grader blade before application. Apply in at least 100 gal/a water. Pave as soon as possible after applying.

Caution Do not allow treated soil to wash or move into untreated area. Do not apply under asphalt coatings less than 2 inches thick. Desirable plants may be killed or injured if herbicide is applied where roots are or may extend.

Site of action Group 5: photosystem II inhibitor

Chemical family Triazine

sodium chlorate + sodium metaborate tetrahydrate (Monobor-chlorate)

Rate 0.9 lb of Monobor-chlorate per 100 sq ft

Time After subgrade is finished and before asphalt paving.

Remarks Do not apply where tree roots extend into treated area. Do not let runoff water wash the herbicide away from treated area. Granules may be dissolved in water and sprayed on, or may be applied dry and followed with at least 2 gal water/100 sq ft. Reentry interval is 12 hours.

Site of action None generally accepted

Chemical family Inorganic

sulfometuron (Oust)

Rate 3 to 6 oz ai/a (4 to 8 oz/a)

Time Apply just before the asphalt or concrete coating to avoid possible lateral movement of the herbicide by rain or mechanical activity.

Remarks Use on parking lots, highway shoulders, median strips, roadways, and other industrial sites. Remove rhizomes, tubers, or other vegetative parts in the site. Will not control woody vegetation such as small trees, brush, or woody vines; their roots must be removed from the site before application.

Caution Do not use under pavement in residential areas such as driveways, or in recreational areas, jogging or bike paths, tennis courts, or golf cart paths. Avoid drift of spray into planters or ornamental bedding areas, or near the treated area, as injury may result. Desirable plants may be injured if their roots extend into treated area.

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

Chemical family Sulfonylurea

trifluralin (Treflan)

Rate 12 to 16 lb ai/a

Time Apply after final grade is established or after additions of base rock.

Remarks Remove rhizomes, tubers, stolons, or other vegetative plant parts by scalping with a grader blade deep enough to ensure their complete removal before application. After applying, do not move soils, and pave as soon as possible. Forms a vapor barrier, preventing roots and shoots from penetrating. Safe to use near desirable vegetation.

Caution Herbicide is volatile and will be lost if not immediately covered by paving. Do not apply to areas where asphalt will be laid directly on soil.

Site of action Group 3: microtubule assembly inhibitor

Chemical family Dinitroaniline

sulfometuron + chlorsulfuron (Landmark XP)

Rate Consult label; each formulation has a different use rate

Time Apply immediately before paving to avoid lateral movement of the herbicide that can result from soil movement caused by rain or mechanical activity.

Remarks Before applying, use a grader blade to scalp and remove rhizomes, tubers, and other vegetative plant parts.

Caution Do not use under pavement in residential or recreational areas. Desirable plants may be injured if their roots extend into treated areas or if planted in treated areas.

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

Chemical family (both) sulfonylurea

tebuthiuron (Spike 80DF)

Rate 1.6 to 4 lb ai/a

Time Apply immediately before paving to avoid lateral movement of the herbicide that can result from soil movement caused by rain or mechanical activity.

Remarks Before applying, use a grader blade to scalp and remove rhizomes, tubers, and other vegetative plant parts.

Caution Do not use under pavement in residential or recreational areas. Desirable plants may be injured if their roots extend into treated areas or if planted in treated areas.

Site of action Group 7: photosystem II inhibitor

Chemical family Substituted urea