Not all registered pesticides are listed. The following are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management, the pesticide's properties, and application timing. Tank mixes may be necessary to achieve desired control; see Susceptibility of Weeds to Herbicide Control for information on specific weed control. Always read the label of the product being used.
SITE PREPARATION – BEFORE PLANTING
Preemergence (before weeds emerge)
A.
NORFLURAZON
(Solicam DF)
Label rates
12
60
WSSA MODE-OF-ACTION GROUP NUMBER1: 12
COMMENTS: Rate depends on soil texture (see label). Do not apply to the soil under young trees (trees less than about 3 years old). Apply to soil as a directed spray from fall to early spring. If no rainfall occurs within 4 weeks, incorporate with sprinkler irrigation. Can suppress yellow nutsedge or bermudagrass when used year after year. Remove existing weeds (e.g., with cultivation, hand-weeding, or a postemergence herbicide) because it has no postemergence activity. Avoid higher rates on sandy or gravelly soils to reduce risk of injury to trees. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Do not use in the Coachella Valley. Apply in 20 to 100 gal water/acre. Residual period: 6 to 12 months.
B.
OXYFLUORFEN
1.25–2 lb a.i.
(Goal 2XL)
5–8 pts
24
30
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Has pre- and some postemergence activity. Do not mechanically disturb the soil after application or poor residual weed control may result. Apply in a minimum of 20 gallons of water per acre. Do not apply between bud swell and final harvest or when fruit are present as injury may occur. Residual period: 4 to 10 months.
C.
ORYZALIN
2–6 lb a.i.
(Surflan)
2–6 qts
24
NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: Apply to the soil surface in 20 to 60 gal water/acre. If rain does not occur within 21 days after application, sprinkle irrigate with 0.5 to 2 inches of water. May be combined with a postemergence herbicide if weeds are present. The higher rates give the longest soil residual. Usually used at 4 lb a.i./acre. Chemigation with oryzalin is possible; see label for instructions. Residual period: 4 to 10 months.
D.
SIMAZINE*
2–4 lb a.i.
(Princep 4L)
2–4 qt
12
NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 5
COMMENTS: Do not apply to the soil under avocado trees. Make one application per year, or split the application between fall and spring. Simazine is frequently used in combination with other preemergence herbicides. Use the high rate for heavy soils and the low rate for lighter soils. Do not use on gravel, sand, or loamy sand soils. Limit first irrigation after application to 0.5 inch. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Residual period: 8 to 12 months.
Postemergence (established weeds)
A.
CARFENTRAZONE
0.024–0.31 lb a.i.
(Shark EW)
2.0 fl oz
12
3
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: For best activity, apply when weeds are still actively growing, less than 4 inches tall or rosettes less than 3 inches wide. Provides control of emerged annual broadleaves, but has no preemergence activity. A nonionic surfactant or crop oil concentrate or methylated seed oil is required. Can be mixed with other herbicides that have pre- or post-emergence activity for broader spectrum weed control. Can be applied anytime during the season. Apply in a minimum of 20 gallons of water per acre. Do not allow contact with desirable fruit, foliage, bloom, or bark, use hooded sprayers during application.
B.
FLUAZIFOP-P-BUTYL
0.125–0.375 lb a.i.
(Fusilade DX)
16–24 fl oz
12
NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For use on nonbearing trees only. Apply to actively growing grasses when they are 2 to 8 inches in height. Add a crop oil concentrate or a nonionic surfactant according to the label for the amount of water (5–40 gal/acre) added. For bermudagrass apply to 4- to 8-inch runners; for johnsongrass apply before boot stage. Do not apply to grasses, which are stressed due to moisture, temperature, low soil fertility, mechanical, or chemical injury. Do not apply more than 72 fl oz/acre per season.
C.
GLYPHOSATE
0.7–3.7 lb a.e.
(Roundup)
11 fl oz–3.3 qt
See label
See label
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Apply with a controlled applicator, low pressure flat fan nozzles, or with drift-reducing nozzles. For annual weed control use 10 to 40 gal water/acre with 1 lb/acre of glyphosate. Using the lower range of water (10-20 gal water/acre) with 1 lb/acre of glyphosate is generally more effective. Ammonium sulfate can also be added (1 to 2% by weight or 8.5 to 17 lbs per 100 gallon of water) to the spray solution to improve control in areas with hard water. It is important to add the ammonium sulfate to the water before adding the herbicide. Apply to young annuals or vigorously growing flowering perennial weeds. Some perennials require the high label rate for control. May be used on young weeds in strip that will be the tree row, followed by planting into the dead weeds. Weeds should not be cultivated for 7 to 14 days after treatment to obtain maximum control. New weeds usually do not establish for a month or more, because of the no-till effect. Residual period: less than 1 month.
D.
PARAQUAT*
0.50 lb a.i.
(Gramoxone SL2.0)
2.5–4.0 pts
24
—
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Best control of annual weeds when they are in the two- to four-leaf stage. Less effective against perennials that will regrow (bermudagrass, dallisgrass, johnsongrass, and bindweed). Older weeds require higher herbicide rates. Apply in a minimum of 20 gallons of water per acre. Use 0.5% nonionic surfactant. Do not allow contact with desirable fruit, foliage, blooms, or bark, use hooded sprayers during application. Do not apply more than 4 times a year.
E.
SETHOXYDIM
0.28–0.47 lb a.i.
(Poast)
1.5–2.5 pt
12
365
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For use on nonbearing trees only. Apply to young annual or perennial grasses. Repeat applications will be required for the control of perennial grasses. Add 2 pt crop oil concentrate to the spray solution. Do not apply to grass that is stressed or poor control may result. Residual period: less than 1 month.
AFTER PLANTING – NONBEARING TREES
Premergence (before weeds emerge)
A.
FLUMIOXAZIN
0.191–0.383 lb a.i.
(Chateau)
6–12 oz
12
1 year
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: For use on nonbearing trees only. Do not apply to trees established less than one year unless protected from spray contact. Best control is achieved when irrigation or rainfall follows within 21 days of application. It will not provide adequate control of emerged weeds unless tankmixed with a postemergence herbicide. Do not apply to row middles (area between berms).
B.
ISOXABEN
0.66–0.9975 lb a.i.
(Gallery 75 dry flowable)
0.66–1.33 lb
12
1 year
WSSA MODE-OF-ACTION GROUP NUMBER1: 21
COMMENTS: For use on nonbearing trees only. Wait until soil has settled around transplant to apply. Treatments are most effective when adequate rainfall or irrigation is received within 21 days after application for incorporation. Will not control grasses or sedges.
C.
NORFLURAZON
(Solicam DF)
Label rates
12
60
WSSA MODE-OF-ACTION GROUP NUMBER1: 12
COMMENTS: Rate depends on soil texture (see label). Do not apply to the soil under young trees (trees less than about 3 years old). Apply to soil as a directed spray from fall to early spring. If no rainfall occurs within 4 weeks, incorporate with sprinkler irrigation. Can suppress yellow nutsedge or bermudagrass when used year after year. Remove existing weeds with cultivation or a postemergence herbicide, because it has no postemergence activity. Avoid higher rates on sandy or gravelly soils to reduce risk of injury to trees. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Apply in 20 to 100 gal water/acre. Residual period: 6 to 12 months.
D.
ORYZALIN
2–6 lb a.i.
(Surflan)
2–6 qt
24
NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: Apply to the soil surface in 20 to 60 gal water/acre. If rain does not occur within 21 days after application, sprinkle irrigate with 0.5 to 2 inches water. May be combined with a postemergence herbicide if weeds are present. The higher rates give the longest soil residual. Usually used at 4 lb a.i./acre. Chemigation with oryzalin is possible, see label for instructions. Residual period: 4 to 10 months. Can be tank-mixed with glyphosate.
Postemergence (established weeds)
A.
CARFENTRAZONE
0.024–0.31 lb a.i.
(Shark EW)
2.0 fl oz
12
3
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: For best activity, apply when weeds are still actively growing, less than 4 inches tall or rosettes less than 3 inches wide. Provides control of emerged annual broadleaves, but has no preemergence activity. A nonionic surfactant or crop oil concentrate or methylated seed oil is required. Can be mixed with other herbicides that have pre- or post-emergence activity for broader spectrum weed control. Can be applied anytime during the season. Apply in a minimum of 20 gallons of water per acre. Do not allow contact with desirable fruit, foliage, bloom, or bark, use hooded sprayers during application.
B.
FLUAZIFOP-P-BUTYL
0.125–0.375 lb a.i.
(Fusilade DX)
See Label
12
NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For use on nonbearing trees only. Apply to actively growing grasses when they are 2 to 8 inches in height. Add a crop oil concentrate or a nonionic surfactant according to the label for the amount of water (5–40 gal/acre) added. For bermudagrass apply to 4- to 8-inch runners; for johnsongrass apply before boot stage. Do not apply to grasses which are stressed due to moisture, temperature, low soil fertility, mechanical, or chemical injury. Do not apply more than 72 fl oz/acre per season.
C.
GLYPHOSATE
0.7–3.7 lb a.e.
(Roundup)
11 fl oz–3.3 qt
See label
See label
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Apply with a controlled applicator, low pressure flat fan nozzles, or with drift-reducing nozzles. Contact with spray or drift can severely damage avocado. For annual weed control use 10 to 40 gal water/acre with 1 lb/acre of glyphosate. Using the lower range of water (10–20 gal water/acre) with 1 lb/acre of glyphosate is generally more effective. Ammonium sulfate can also be added (1 to 2% by weight or 8.5 to 17 lbs per 100 gallon of water) to the spray solution to improve control in areas with hard water. It is important to add the ammonium sulfate to the water before adding the herbicide. Apply to young annuals or vigorously growing flowering perennial weeds. Some perennial weeds require the high label rate for control. May be used on young weeds in strip that will be the tree row, followed by planting into the dead weeds. Weeds should not be cultivated for 7 to 14 days after treatment to obtain maximum control. New weeds usually do not establish for a month or more, because of the no-till effect. Can be tank-mixed with oryzalin.
D.
PARAQUAT*
0.50 lb a.i.
(Gramoxone SL2.0)
2.5–4.0 pts
24
—
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Best control of annual weeds when they are in the two- to four-leaf stage. Less effective against perennials that will regrow (bermudagrass, dallisgrass, johnsongrass and bindweed). Older weeds require higher herbicide rates Apply in a minimum of 20 gallons of water per acre. Use 0.5% nonionic surfactant. Do not allow contact with desirable fruit, foliage, blooms, or bark, use hooded sprayers during application. Do not apply more than 4 times a year.
E.
SETHOXYDIM
0.28–0.47 lb a.i.
(Poast)
1.5–2.5 pt
12
365
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For use on nonbearing trees only. Apply to young annual or perennial grasses. Repeat applications will be required for the control of perennial grasses. Add 2 pt crop oil concentrate to the spray solution. Do not apply to grass that is stressed or poor control may result. Residual period: less than 1 month.
ESTABLISHED TREES
Preemergence (before weeds emerge)
A.
NORFLURAZON
(Solicam DF)
Label rates
12
60
WSSA MODE-OF-ACTION GROUP NUMBER1: 12
COMMENTS: Rate depends on soil texture (see label). Do not apply to the soil under young trees (trees less than about 3 years old). Apply to soil as a directed spray from fall to early spring. If no rainfall occurs within 4 weeks, incorporate with sprinkler irrigation. Can suppress yellow nutsedge or bermudagrass when used year after year. Remove existing weeds (e.g., with cultivation, hand-weeding, or a postemergence herbicide) because it has no postemergence activity. Avoid higher rates on sandy or gravelly soils to reduce risk of injury to trees. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Do not use in the Coachella Valley. Apply in 20 to 100 gal water/acre. Residual period: 6 to 12 months.
B.
ORYZALIN
2–6 lb a.i.
(Surflan)
2–6 qts
24
NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: Apply to the soil surface in 20 to 60 gal water/acre. If rain does not occur within 21 days after application, sprinkle irrigate with 0.5 to 2 inches water. May be combined with a postemergence herbicide if weeds are present. The higher rates give the longest soil residual. Usually used at 4 lb a.i./acre. Chemigation with oryzalin is possible; see label for instructions. Residual period: 4 to 10 months.
C.
OXYFLUORFEN
1.25–2 lb a.i.
(Goal 2XL)
5–8 pts
24
30
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Has pre- and some postemergence activity. Do not mechanically disturb the soil after application or poor residual weed control may result. Apply in a minimum of 20 gallons of water per acre. Do not apply between bud swell and final harvest or when fruit are present as injury may occur. Residual period: 4 to 10 months.
D.
SIMAZINE*
2–4 lb a.i.
(Princep 4L)
2–4 qt
12
NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 5
COMMENTS: Do not apply to the soil under avocado trees. Make one application per year, or split the application between fall and spring. Simazine is frequently used in combination with other preemergence herbicides. Use the high rate for heavy soils and the low rate for lighter soils. Do not use on gravel, sand, or loamy sand soils. Limit first irrigation after application to 0.5 inch. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Residual period: 8 to 12 months.
Postemergence (after weeds emerge)
A.
CARFENTRAZONE
0.024–0.31 lb a.i.
(Shark EW)
2.0 fl oz
12
3
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: For best activity, apply when weeds are still actively growing, less than 4 inches tall or rosettes less than 3 inches wide. Provides control of emerged annual broadleaves, but has no preemergence activity. A nonionic surfactant or crop oil concentrate or methylated seed oil is required. Can be mixed with other herbicides that have pre- or post-emergence activity for broader spectrum weed control. Can be applied anytime during the season. Apply in a minimum of 20 gallons of water per acre. Do not allow contact with desirable fruit, foliage, bloom, or bark, use hooded sprayers during application.
B.
GLYPHOSATE
0.7–3.7 lb a.e.
(Roundup)
11 fl oz–3.3 qt
See label
See label
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Apply with a controlled applicator or with low pressure flat fan nozzles. Contact with spray or drift can severely damage avocado. For annual weed control use 10 to 40 gal water/acre with 1 lb/acre of glyphosate. Using the lower range of water (10 to 20 gal water/acre) with 1 lb/acre of glyphosate is generally more effective. Ammonium sulfate can also be added (1 to 2% by weight or 8.5 to 17 lbs per 100 gallon of water) to the spray solution to improve control in areas with hard water. It is important to add the ammonium sulfate to the water before adding the herbicide. Apply to young annuals or vigorously growing flowering perennial weeds. Some perennial weeds require the high label rate for control. May be used on young weeds in strip that will be the tree row, followed by planting into the dead weeds. Weeds should not be cultivated for 7 to 14 days after treatment to obtain maximum control. New weeds usually do not establish for a month or more, because of the no-till effect. Can be tank-mixed with oryzalin.
C.
OXYFLUORFEN
1.25–2 lb a.i.
(Goal 2XL)
5–8 pts
24
30
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Has pre- and some postemergence activity. Herbicide can be used on weed-free soil to prevent germination of a wide variety of weeds or it can be applied to existing weeds at seedling stage especially with a tank mix partner to increase the variety of weeds controlled and/or the length of residual control. Do not mechanically disturb the soil after application or poor residual weed control may result. Apply in a minimum of 20 gallons of water per acre. Do not apply between bud swell and final harvest or when fruit are present as injury may occur. Residual period: 4 to 10 months.
D.
PARAQUAT*
0.50 lb a.i.
(Gramoxone SL2.0)
2.5–4.0 pts
24
—
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Best control of annual weeds when they are in the two- to four-leaf stage. Less effective against perennials that will regrow (bermudagrass, dallisgrass, johnsongrass and bindweed). Older weeds require higher herbicide rates Apply in a minimum of 20 gallons of water per acre. Use 0.5% nonionic surfactant. Do not allow contact with desirable fruit, foliage, bloom, or bark, use hooded sprayers during application. Do not apply more than 4 times a year.
E.
SETHOXYDIM
0.28–0.47 lb a.i.
(Poast)
1.5–2.5 pt
12
365
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For use on nonbearing trees only. Apply to young annual or perennial grasses. Repeat applications will be required for the control of perennial grasses. Add 2 pt crop oil concentrate to the spray solution. Do not apply to grass that is stressed or poor control may result. Residual period: less than 1 month.
‡
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest.
*
Permit required from county agricultural commissioner for purchase or use.
NA
Not applicable.
1
Group numbers are assigned by the Weed Science Society of America (WSSA) according to different modes of action. Although weeds may exhibit multiple resistance across many groups, mode of action numbers are useful in planning mixtures or rotations of herbicides with different modes of action.
Text Updated: 09/16
Treatment Table Updated: 09/16