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Agriculture: Walnut Pest Management Guidelines

Herbicide Treatment Table

Weeds Pages

Common name Amount per acre REI‡ PHI‡
(Example trade name) (hours) (days)
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 the Susceptibility of Weeds to Herbicide Control for information on specific weed control. Always read the label of the product being used.
PREPLANT
Preemergence (before weeds germinate)
A. ORYZALIN 2–6 lb a.i.
(Surflan A.S.) 2–6 qt 24 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: May be applied preplant incorporated or preplant surface before transplanting or after transplanting trees. If using prior to planting, plant tree roots below treated soil and do not place treated soil near roots during planting. Considered safe for young or newly planted trees and on sandy or sandy loam soils. Do not apply over the foliage or buds to avoid crop injury. If rainfall of 0.5 to 1 inch does not occur within 21 days of treatment, sprinkle irrigate with 0.5 to 2 inches of water. Will not control emerged weeds. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
B. PENDIMETHALIN 1.9–5.985 lb a.i.
(Prowl H2O) 2–6.3 qt 24 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: May be applied preplant incorporated or preplant surface before transplanting or after transplanting trees. If using prior to planting, plant tree roots below treated soil and do not place treated soil near roots during planting. Do not apply to newly seeded nursery stock. Do not apply over the foliage or buds to avoid crop injury. Best control is achieved when irrigation or rainfall occurs within 7 days. Will not control emerged weeds. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
C. TRIFLURALIN 0.5–1 lb a.i.
(Treflan HFP) 1–2 pt 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: Can be used preplant incorporated by power tillage or irrigation. Plant tree roots below treated soil. Do not place treated soil near roots during planting. Recommended rate depends on soil type. Can use spray blade applicator for suppression of field bindweed. Residual period: 2 to 12 months.
Postemergence (after weeds emerge)
A. AMMONIUM NONANOATE
(AXXE)# 6–15% v/v 24 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: —
COMMENTS: Do not apply to weeds wet from dew rain or irrigation or if rain or irrigation is expected within 2 hours.
B. CAPRIC ACID/CAPRYLIC ACID
(Suppress)# 3–9% v/v 24 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: —
COMMENTS: Apply as a directed spray; avoid green bark. Do not apply to weeds wet from dew rain or irrigation or if rain or irrigation is expected within 4 hours.
C. GLYPHOSATE 0.387–3.713 lbs a.e.
(Roundup PowerMax) 11 fl oz–3.3 qt 4 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Can be applied prior to planting, within or between tree rows, with shielded or wiper equipment, or as directed spot sprays. Apply to young, actively growing annual weeds or perennial weeds when flowering. Some perennials may require the higher label rate for acceptable control. Add ammonium sulfate to spray solution at 5 to 10 lb per 100 gal water prior to adding glyphosate to improve control. Use 10 to 40 gal water/acre with 1 lb a.e./acre for annual weeds. Avoid applications to foliage or green bark, or mechanical wounds as injury can occur.
D. NONANOIC ACID
(Scythe)# 1–10% v/v 12 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 26
COMMENTS: Apply as a directed spray; avoid green bark.
E. PARAQUAT* 0.3125–1 lb a.i.
(Gramoxone SL 2.0) 2.5–4 pt 24 —
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Use in 20 to 60 gal water/acre when weeds are in the seedling stage with good cover of the weed foliage. Add a non-ionic surfactant at 0.5% volume by volume. Repeated applications will be required as new weeds emerge or surviving plants regrow. Do not allow spray to contact foliage or green bark (except suckers); shields or wraps recommended for young trees.
NEWLY PLANTED ORCHARDS (3 years or less since planting)
Preemergence
A. DIURON 1.6–3 lbs ai
(Drexel Diuron 80) 2–3.75 lbs 12 See label
(Diuron 4L) 1.6–3 qt 12 See label
WSSA MODE-OF-ACTION GROUP NUMBER 7
COMMENTS: Do not apply more than 3.75 lb of Diuron 80 or 3 qt Diuron 4L per year. Use on trees established in orchard at least 1 year. See label for soil restrictions
B. FLUMIOXAZIN 0.1913–0.3825 lb a.i.
(Chateau) 6–12 oz 12 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Do not use in nut trees established less than one year, unless protected from spray contact by non-porous tree protectors. Check supplemental label for additional restrictions in Merced, San Joaquin, and Stanislaus Counties. Residual period: approximately 1 month for each 2 oz/ acre product used.
C. HALOSULFURON 0.0309–0.0607 lb a.i.
(Sandea) 0.66–1.33 oz 12 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Use on trees established by being transplanted into their final growing location for a period of at least 12 months. See label for further extensive soil restrictions and cautions, especially if within 4 miles of prunes and 1 mile of cotton.
D. INDAZIFLAM 0.046–0.085 lb a.i.
(Alion) 3.5–6.5 fl oz 12 14
WSSA MODE-OF-ACTION GROUP NUMBER1: 29
COMMENTS: Can be used in tree nuts established in the orchard at least one year. Recommended rate depends on soil organic matter content. Do not use on soils with greater than 20% gravel content. In southern San Joaquin Valley counties, applications are limited to between harvest and emergence of green leaf tissue. Requires rainfall or irrigation within 21 days following treatment. Residual period: 5 to 8 months.
E. ISOXABEN 0.52–1 lb a.i.
(Trellis SC) 16–31 fl oz 12 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 21
COMMENTS: Can be used in new plantings and established tree nut orchards. In new plantings, soil must be settled around transplants by packing and irrigation or rainfall and no cracks present. Do not apply over the top of young trees as bud injury can occur. When replanting ensure that planting holes are not refilled with treated soil. Isoxaben controls broadleaf weeds only. Rainfall or irrigation of at least 0.5 inch should occur within 21 days of treatment to activate herbicide. Residual period: 4 to 6 months.
F. NORFLURAZON 1.965–3.93 lb a.i.
(Solicam DF) 2.5–5 lb 12 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 12
COMMENTS: The maximum rate is determined by soil texture. Use only on trees planted at least 18 months. Norflurazon is known to leach through soil into ground water under certain conditions.
G. ORYZALIN 2–6 lb a.i
(Surflan A.S.) 2–6 qt 24 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: May be applied preplant incorporated or preplant surface before transplanting or after transplanting trees. If using prior to planting, plant tree roots below treated soil and do not place treated soil near roots during planting. Considered safe for young or newly planted trees and on sandy or sandy loam soils. Do not apply over the foliage or buds to avoid crop injury. If rainfall of 0.5 to 1 inch does not occur within 21 days of treatment, sprinkle irrigate with 0.5 to 2 inches of water. Will not control emerged weeds. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
H. OXYFLUORFEN 0.5–2 lb ai
(Goal 2XL) 1–8 pts 24 7
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Rate range differs for dormant and non-dormant orchards and for different methods of application; see label for use period, cut-off dates, and other restrictions. Oxyfluorfen can be used after transplanting nut trees or in established orchards. Has both preemergence and postemergence activity; lower rates typically used for postemergence control while higher rates provide longer residual control. At least 0.75 inch rainfall or irrigation must be received within 3 to 4 weeks after treatment. Do not disturb with mechanical equipment or poor weed control will result. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations. Regulations affect use for the San Joaquin Valley from May 1 to October 31, 2019. Review the Department of Pesticide Regulation's updated fact sheet. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
I. PENDIMETHALIN 1.9–5.985 lb a.i.
(Prowl H2O) 2–6.3 qt 24 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: May be applied preplant incorporated or preplant surface before transplanting or after transplanting trees. If using prior to planting, plant tree roots below treated soil and do not place treated soil near roots during planting. Do not apply to newly seeded nursery stock. Do not apply over the foliage or buds to avoid crop injury. Best control is achieved when irrigation or rainfall occurs within 7 days. Will not control emerged weeds. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
J. PENOXSULAM/OXYFLUORFEN 0.016–0.031 lb a.i. (penoxsulam)
/0.74–1.47 lb a.i. (oxyfluorfen)
(Pindar GT) 1.5–3 pt 24 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 2/14
COMMENTS: Can be used in walnuts established at least 9 months. Rainfall or irrigation of at least 0.5 inches needed within 21 days of application for most effective performance. Use lower rates on lighter soils and higher rates on heavier soils. When replacing trees, make sure clean soil is used around the roots of replants. Use tree protectors to avoid contact with foliage or green bark. Applications recommended between harvest and emergence of green leaf tissue. Residual period: 5 to 8 months.
K. RIMSULFURON 0.0625 lb a.i.
(Matrix SG) 4 oz 4 14
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Preplant and postemergence control of certain grasses and broadleaf weeds in trees at least 12 months since transplanting. Apply as a broadcast or band treatment directed at the base of the trunk in 10 to 20 gal water/acre. Best results when applied to moist soil or about 0.5 inch rainfall or irrigation occurs within 2 weeks after application. Add nonionic surfactant to increase postemergence activity. Avoid contact with foliage or fruit. Spray solutions below pH 4 or above pH 8 may reduce performance. Chemigation is allowed: see label for instructions. Residual period: 2 to 4 months.
L. SULFENTRAZONE
(Zeus) See comments 12 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Do not apply more than 12 oz (0.375 lb ai) in 12 months. Apply only to trees established one full year; avoid green bark: young trees should be protected. Delay replanting into established orchards at least 30 days after applying Zeus and use untreated soil. See label for California Specific restrictions on applications of Zeus herbicide, especially if in runoff or leaching ground water protection area.
M. TRIFLURALIN 0.5–1 lb a.i.
(Treflan HFP) 1–2 pt 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: Can be used preplant incorporated by power tillage or irrigation. Plant tree roots below treated soil. Do not place treated soil near roots during planting. Recommended rate depends on soil type. Rate range for new plantings is 1 to 2 pt/acre while established orchard rate range is 2 to 4 pt/acre. Can use spray blade applicator for suppression of field bindweed. Residual period: 2 to 12 months.
Postemergence
A. 2,4-D 1–1.4 lb ae
(Orchard Master) 2–3 pt 48 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 4
COMMENTS: For use in orchards established at least one year. Selective control of most annual broadleaf species and control or suppression of perennial broadleaf weeds. May be used as a broadcast treatment to middles or banded within the tree row. Use caution to avoid contact with tree fruit, foliage, stems, lower limbs, and exposed roots. Do not use on sandy or shallow soils and do not apply immediately before an irrigation.
B. AMMONIUM NONANOATE
(AXXE)# 6–15% 24 See label
WSSA MODE-OF-ACTION GROUP NUMBER1: —
COMMENTS: Do not apply to weeds wet from dew rain or irrigation or if rain or irrigation is expected within 2 hours.
C. CAPRIC ACID/CAPRYLIC ACID
(Suppress)# 3–9% v/v 24 See label
WSSA MODE-OF-ACTION GROUP NUMBER1: —
COMMENTS: Apply as a directed spray; avoid green bark. Do not apply to weeds wet from dew rain or irrigation or if rain or irrigation is expected within 4 hours.
D. CARFENTRAZONE 0.03 lb a.i.
(Shark EW) 2 fl oz 12 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Selective on small, vigorously growing broadleaf weeds. Do not allow spray droplets to contact desirable fruit, foliage, flowers, or green stem tissue as injury can occur. Thorough coverage is needed for best performance.
E. CLETHODIM 0.068–0.121 lb a.i.
SelectMax 9–16 fl oz 24 365
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For use only in nonbearing tree nut orchards (no harvest within one year). For selective control of annual grasses that are actively growing, before tillering, and not stressed for moisture. Repeated applications may be needed on perennial grasses. A crop oil concentrate (1% volume by volume) or nonionic surfactant (0.25% volume by volume) must be added. Use in 20 to 40 gallons water/acre.
F. DIQUAT 0.375–0.5 lb a.i.
(Reglone) 1.5–2 pt 24 365
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: For use only in nonbearing tree nut orchards (no harvest within one year). Can be used prior to planting and up to one year before first harvest for non-selective burndown of grasses and broadleaf weeds. Do not allow spray droplets to contact desirable fruit, foliage, flowers, or green stem tissue as injury can occur. Thorough coverage is needed for best performance.
G. FLUAZIFOP-P-BUTYL 0.25–0.375 lb a.i.
(Fusilade DX) 16–24 oz 12 365
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For use only in nonbearing tree nut orchards (no harvest within one year). For selective control of annual grasses that are actively growing, before tillering, and not stressed for moisture. Repeated applications may be needed on perennial grasses. A crop oil concentrate (1% volume by volume) or nonionic surfactant (0.25% volume by volume) must be added.
H. GLUFOSINATE 0.878–1.5 lb a.i.
(Rely 280) 48–82 fl oz 12 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 10
COMMENTS: Nonselective control of annual broadleaf and grass weeds and burndown of perennial weeds. Can be used as banded, broadcast, or spot treatments. Add ammonium sulfate to spray solution prior to adding glyphosate to improve control. Use higher rates and greater application volume for large weeds or dense vegetation. Use tree protectors until trunks have mature, calloused brown bark and avoid contact with green bark, stems, foliage or fruit as injury can occur.
I. GLYPHOSATE 0.387–3.713 lbs a.e.
(Roundup PowerMax) 11 fl oz–3.3 qt 4 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Can be applied prior to planting, within or between tree rows, with shielded or wiper equipment, or as directed spot sprays. Apply to young, actively growing annual weeds or perennial weeds when flowering. Some perennials may require the higher label rate for acceptable control. Add ammonium sulfate to spray solution at 5 to 10 lb per 100 gal water prior to adding glyphosate to improve control. Use 10 to 40 gal water/acre with 1 lb a.e./acre for annual weeds. Avoid applications to foliage or green bark, or mechanical wounds as injury can occur.
J. HALOSULFURON 0.0309–0.0607 lb a.i.
(Sandea) 0.66–1.33 oz 12 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Use on trees established by being transplanted into their final growing location for a period of at least 12 months. See label for further extensive soil restrictions and cautions, especially if within 4 miles of prunes and 1 mile of cotton.
K. MESOTRIONE
(Broadworks) See comments 12 30
WSSA MODE-OF-ACTION GROUP NUMBER1: 27
COMMENTS: Only for use on trees established at least 12 months. Do not apply more than 6 oz. (0.188 lbs a.i.) in the first application or more than 12 oz (0.376 lbs a.i.) per 12 months, with no more than three applications per year. Do not apply to trees under stress.
L. NONANOIC ACID
(Scythe)# 1–10% v/v 12 See label
WSSA MODE-OF-ACTION GROUP NUMBER1: 26
COMMENTS: Apply as a directed spray; avoid green bark.
M. OXYFLUORFEN 0.5–2 lb ai
(Goal 2XL) 1–8 pts 24 7
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Rate range differs for dormant and non-dormant orchards and for different methods of application; see label for use period, cut-off dates, and other restrictions. Oxyfluorfen can be used after transplanting nut trees or in established orchards. Has both preemergence and postemergence activity; lower rates typically used for postemergence control while higher rates provide longer residual control. At least 0.75 inch rainfall or irrigation must be received within 3 to 4 weeks after treatment. Do not disturb with mechanical equipment or poor weed control will result. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations. Regulations affect use for the San Joaquin Valley from May 1 to October 31, 2019. Review the Department of Pesticide Regulation’s updated fact sheet. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
N. PARAQUAT* 0.625–1 lb a.i.
(Gramoxone SL 2.0) 2.5–4 pt 24 —
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Use in 20 to 60 gal water/acre when weeds are in the seedling stage with good cover of the weed foliage. Add a non-ionic surfactant at 0.5% volume by volume. Repeated applications will be required as new weeds emerge or surviving plants regrow. Do not allow spray to contact foliage or green bark (except suckers); shields or wraps recommended for young trees.
O. PYRAFLUFEN-ETHYL 0.0027–0.0053 lb a.i.
(Venue) 2–4 fl oz 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Selective on small, vigorously growing broadleaf weeds. Add crop oil concentrate and ensure thorough coverage for best performance. Use higher rates for large weeds and for sucker control. Do not allow spray droplets to contact desirable fruit, foliage, flowers, or green stem tissue as injury can occur; shields or tree wraps recommended for young trees.
P. RIMSULFURON 0.0625 lb a.i.
(Matrix SG) 4 oz 4 14
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Preplant and postemergence control of certain grasses and broadleaf weeds in trees at least 12 months since transplanting. Apply as a broadcast or band treatment directed at the base of the trunk in 10 to 20 gal water/acre. Best results when applied to moist soil or about 0.5 inch rainfall or irrigation occurs within 2 weeks after application. Add nonionic surfactant to increase postemergence activity. Avoid contact with foliage or fruit. Spray solutions below pH 4 or above pH 8 may reduce performance. Chemigation is allowed: see label for instructions. Residual period: 2 to 4 months.
Q. SAFLUFENACIL 0.04375 lb a.i.
(Treevix) 1 oz 12 7
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Selective control of annual broadleaf weeds. Can be used as banded, broadcast, or spot treatments. Add methylated seed oil and ammonium sulfate or ammonium nitrate for best performance. Spray contact with tree foliage, flowers, buds or fruit can result in crop injury.
R. SETHOXYDIM 0.281–0.375 lb a.i.
(Poast) 1.5–2 pt 12 15
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For selective control of annual grasses that are actively growing, before tillering, and not stressed for moisture. Can be used as banded, broadcast, or spot treatments. Can be sprayed over the top of small nonbearing trees. Repeated applications may be needed on perennial grasses. Add crop oil concentrate or methylated seed oil for best performance; ammonium sulfate or ammonium nitrate will enhance activity on some grass weeds.
ESTABLISHED ORCHARDS
Preemergence
A. DIURON 1.6–3 lbs ai
(Drexel Diuron 80) 2–3.75 lbs 12 See label
(Diuron 4L) 1.6–3 qt 12 See label
WSSA MODE-OF-ACTION GROUP NUMBER1:7
COMMENTS: Do not apply more than 3.75 lb of Diuron 80 or 3 qt Diuron 4L per year. Use on trees established in orchard at least 1 year. See label for soil restrictions
B. FLAZASULFURON 0.033–0.0445 lb a.i.
(Mission) 2.14–2.85 oz 12 130
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Do not use on trees established less than three years; protective sleeves must be used on 3-year-old trees. Direct spray to soil beneath trees, but do not apply where roots are exposed. Do not apply to saturated soils or mechanically incorporate into the soil.
C. FLUMIOXAZIN 0.1913–0.3825 lb a.i.
(Chateau) 6–12 oz 12 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Do not use in nut trees established less than one year, unless protected from spray contact by non-porous tree protectors. Check supplemental label for additional restrictions in Merced, San Joaquin, and Stanislaus Counties. Residual period: approximately 1 month for each 2 oz/acre product used.
D. HALOSULFURON 0.0309–0.0607 lb a.i.
(Sandea) 0.66–1.33 oz 12 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Use on trees established by being transplanted into their final growing location for a period of at least 12 months. See label for further extensive soil restrictions and cautions, especially if within 4 miles of prunes and 1 mile of cotton.
E. INDAZIFLAM 0.046–0.085 lb a.i.
(Alion) 3.5–6.5 fl oz 12 14
WSSA MODE-OF-ACTION GROUP NUMBER1: 29
COMMENTS: Can be used in tree nuts established in the orchard at least one year. Recommended rate depends on soil organic matter content. Do not use on soils with greater than 20% gravel content. In southern San Joaquin Valley counties, applications limited to between harvest and emergence of green leaf tissue. Requires rainfall or irrigation within 21 days following treatment. Residual period: 5 to 8 months.
F. ISOXABEN 0.52–1 lb a.i.
(Trellis SC) 16–31 fl oz 12 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 21
COMMENTS: Can be used in new plantings and established tree nut orchards. In new plantings, soil must be settled around transplants by packing and irrigation or rainfall and no cracks present. Do not apply over the top of young trees as bud injury can occur. When replanting, ensure that planting holes are not refilled with treated soil. Isoxaben controls broadleaf weeds only. Rainfall or irrigation of at least 0.5 inch should occur within 21 days of treatment to activate herbicide. Residual period: 4 to 6 months.
G. ORYZALIN 2–6 lb a.i
(Surflan A.S.) 2–6 qt 24 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: May be applied preplant incorporated or preplant surface before transplanting or after transplanting trees. If using prior to planting, plant tree roots below treated soil and do not place treated soil near roots during planting. Considered safe for young or newly planted trees and on sandy or sandy loam soils. Do not apply over the foliage or buds to avoid crop injury. If rainfall of 0.5to 1 inch does not occur within 21 days of treatment, sprinkle irrigate with 0.5 to 2 inches of water. Will not control emerged weeds. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
H. OXYFLUORFEN 0.5–2 lb a.i
(Goal 2XL) 1–8 pts 24 7
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Rate range differs for dormant and non-dormant orchards and for different methods of application; see label for use period, cut-off dates, and other restrictions. Oxyfluorfen can be used after transplanting nut trees or in established orchards. Has both preemergence and postemergence activity; lower rates typically used for postemergence control while higher rates provide longer residual control. At least 0.75 inch rainfall or irrigation must be received within 3 to 4 weeks after treatment. Do not disturb with mechanical equipment or poor weed control will result. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations. Regulations affect use for the San Joaquin Valley from May 1 to October 31, 2019. Review the Department of Pesticide Regulation’s updated fact sheet. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
I. PENDIMETHALIN 1.9–5.985 lb a.i.
(Prowl H2O) 2–6.3 qt 24 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: May be applied preplant incorporated or preplant surface before transplanting or after transplanting trees. If using prior to planting, plant tree roots below treated soil and do not place treated soil near roots during planting. Do not apply to newly seeded nursery stock. Do not apply over the foliage or buds to avoid crop injury. Best control is achieved when irrigation or rainfall occurs within 7 days. Will not control emerged weeds. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
J. PENOXSULAM/OXYFLUORFEN 0.016–0.031 lb a.i. (penoxsulam)
/0.74–1.47 lb a.i. (oxyfluorfen)
(Pindar GT) 1.5–3 pt 24 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 2/14
COMMENTS: Can be used in walnuts established at least 9 months. Rainfall or irrigation of at least 0.5 inches needed within 21 days of application for most effective performance. Use lower rates on lighter soils and higher rates on heavier soils. When replacing trees, make sure clean soil is used around the roots of replants. Use tree protectors to avoid contact with foliage or green bark. Applications recommended between harvest and emergence of green leaf tissue. Residual period: 5 to 8 months.
K. RIMSULFURON 0.0625 lb a.i.
(Matrix SG) 4 oz 4 14
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Preplant and postemergence control of certain grasses and broadleaf weeds in trees at least 12 months since transplanting. Apply as a broadcast or band treatment directed at the base of the trunk in 10 to 20 gal water/acre. Best results when applied to moist soil or about 0.5 inch rainfall or irrigation occurs within 2 weeks after application. Add nonionic surfactant to increase postemergence activity. Avoid contact with foliage or fruit. Spray solutions below pH 4 or above pH 8 may reduce performance. Chemigation is allowed: see label for instructions. Residual period: 2 to 4 months.
L. SIMAZINE 2–4 lb a.i.
(Princep 4L) 2–4 qt 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 5
COMMENTS: Can be used in walnuts established at least 3 years. On lighter soils, use lower rates. Do not use on gravel, sand, or loamy sand soils. If an irrigation is applied immediately after application, limit water 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.
M. SULFENTRAZONE
(Zeus) See comments 12 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Do not apply more than 12 oz (0.375 lb ai) in 12 months. Apply only to trees established one full year; avoid green bark: young trees should be protected. Delay replanting into established orchards at least 30 days after applying Zeus and use untreated soil. See label for ‘California Specific restrictions on Applications of Zeus Herbicide' especially if in runoff or leaching ground water protection area.
N. TRIFLURALIN 0.5–1 lb a.i.
(Treflan HFP) 1–2 pt 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: Can be used preplant incorporated by power tillage or irrigation. Plant tree roots below treated soil. Do not place treated soil near roots during planting. Recommended rate depends on soil type. Rate range for new plantings is 1 to 2 pt/acre while established orchard rate range is 2 to 4 pt/acre. Can use spray blade applicator for suppression of field bindweed. Residual period: 2 to 12 months.
ESTABLISHED ORCHARDS
Postemergence
A. 2,4-D 1–1.4 lb ae
(Orchard Master) 2–3 pt 48 60
WSSA MODE-OF-ACTION GROUP NUMBER1: 4
COMMENTS: For use in orchards established at least one year. Selective control of most annual broadleaf species and control or suppression of perennial broadleaf weeds. May be used as a broadcast treatment to middles or banded within the tree row. Use caution to avoid contact with tree fruit, foliage, stems, lower limbs, and exposed roots. Do not use on sandy or shallow soils and do not apply immediately before an irrigation.
B. AMMONIUM NONANOATE
(AXXE)# 6–15% v/v 24 See label
WSSA MODE-OF-ACTION GROUP NUMBER1: —
COMMENTS: Do not apply to weeds wet from dew rain or irrigation or if rain or irrigation is expected within 2 hours.
C. CAPRIC ACID/CAPRYLIC ACID
(Suppress)# 3–9% v/v 24 See label
WSSA MODE-OF-ACTION GROUP NUMBER1: —
COMMENTS: Apply as a directed spray; avoid green bark. Do not apply to weeds wet from dew rain or irrigation or if rain or irrigation is expected within 4 hours.
D. CARFENTRAZONE 0.03 lb a.i. 12 3
(Shark EW) 2 fl oz
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Selective on small, vigorously growing broadleaf weeds. Do not allow spray droplets to contact desirable fruit, foliage, flowers, or green stem tissue as injury can occur. Thorough coverage is needed for best performance.
E. FLAZASULFURON 0.033–0.0445 lb a.i.
(Mission) 2.14–2.85 oz 12 130
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Do not use on trees established less than three years; protective sleeves must be used on 3-year-old trees. Direct spray to soil beneath trees, but do not apply where roots are exposed. Do not apply to saturated soils or mechanically incorporate into the soil.
F. GLUFOSINATE 0.878–1.5 lb a.i.
(Rely 280) 48–82 fl oz 12 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 10
COMMENTS: Nonselective control of annual broadleaf and grass weeds and burndown of perennial weeds. Can be used as banded, broadcast, or spot treatments. Add ammonium sulfate to spray solution prior to adding glyphosate to improve control. Use higher rates and greater application volume for large weeds or dense vegetation. Use tree protectors until trunks have mature, calloused brown bark and avoid contact with green bark, stems, foliage or fruit as injury can occur.
G. GLYPHOSATE 0.387–3.713 lbs a.e.
(Roundup PowerMax) 11 fl oz–3.3 qt 4 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Can be applied prior to planting, within or between tree rows, with shielded or wiper equipment, or as directed spot sprays. Apply to young, actively growing annual weeds or perennial weeds when flowering. Some perennials may require the higher label rate for acceptable control. Add ammonium sulfate to spray solution at 5 to 10 lb per 100 gal water prior to adding glyphosate to improve control. Use 10 to 40 gal water/acre with 1 lb a.e./acre for annual weeds. Avoid applications to foliage or green bark, or mechanical wounds as injury can occur.
H. HALOSULFURON 0.0309–0.0607 lb a.i.
(Sandea) 0.66–1.33 oz 12 14
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Use on trees established by being transplanted into their final growing location for a period of at least 12 months. See label for further extensive soil restrictions and cautions, especially if within 4 miles of prunes and 1 mile of cotton.
I. MESOTRIONE
(Broadworks) See comments 12 30
WSSA MODE-OF-ACTION GROUP NUMBER1: 27
COMMENTS: Only for use on trees established at least 12 months. Do not apply more than 6 oz. (0.188 lbs a.i.) in the first application or more than 12 oz (0.376 lbs a.i.) per 12 months, with no more than three applications per year. Do not apply to trees under stress.
J. NONANOIC ACID
(Scythe)# 1–10% v/v 12 —
WSSA MODE-OF-ACTION GROUP NUMBER1: 26
COMMENTS: Apply as a directed spray; avoid green bark.
K. OXYFLUORFEN 0.5–2 lb ai
(Goal 2XL) 1–8 pts 24 7
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Rate range differs for dormant and non-dormant orchards and for different methods of application; see label for use period, cut-off dates, and other restrictions. Oxyfluorfen can be used after transplanting nut trees or in established orchards. Has both preemergence and postemergence activity; lower rates typically used for postemergence control while higher rates provide longer residual control. At least 0.75 inch rainfall or irrigation must be received within 3 to 4 weeks after treatment. Do not disturb with mechanical equipment or poor weed control will result. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations. Regulations affect use for the San Joaquin Valley from May 1 to October 31, 2019. Review the Department of Pesticide Regulation’s updated fact sheet. Chemigation is allowed: see label for instructions. Residual period: 4 to 10 months.
L. PARAQUAT* 0.3125–1 lb a.i. —
(Gramoxone SL 2.0) 2.5–4 pt 24 —
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Use in 20 to 60 gal water/acre when weeds are in the seedling stage with good cover of the weed foliage. Add a non-ionic surfactant at 0.5% volume by volume. Repeated applications will be required as new weeds emerge or surviving plants regrow. Do not allow spray to contact foliage or green bark (except suckers); shields or wraps recommended for young trees.
M. PYRAFLUFEN-ETHYL 0.0027–0.0053 lb a.i.
(Venue) 2–4 fl oz 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Selective on small, vigorously growing broadleaf weeds. Add crop oil concentrate and ensure thorough coverage for best performance. Use higher rates for large weeds and for sucker control. Do not allow spray droplets to contact desirable fruit, foliage, flowers, or green stem tissue as injury can occur; shields or tree wraps recommended for young trees.
N. RIMSULFURON 0.0625 lb a.i.
(Matrix SG) 4 oz 4 14
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Preplant and postemergence control of certain grasses and broadleaf weeds in trees at least 12 months since transplanting. Apply as a broadcast or band treatment directed at the base of the trunk in 10 to 20 gal water/acre. Best results when applied to moist soil or about 0.5 inch rainfall or irrigation occurs within 2 weeks after application. Add nonionic surfactant to increase postemergence activity. Avoid contact with foliage or fruit. Spray solutions below pH 4 or above pH 8 may reduce performance. Chemigation is allowed: see label for instructions. Residual period: 2 to 4 months.
O. SAFLUFENACIL 0.04375 lb a.i.
(Treevix) 1 oz 12 7
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Selective control of annual broadleaf weeds. Can be used as banded, broadcast, or spot treatments. Add methylated seed oil and ammonium sulfate or ammonium nitrate for best performance. Spray contact with tree foliage, flowers, buds or fruit can result in crop injury.
P. SETHOXYDIM 0.281–0. 375 lb a.i.
(Poast) 1.5–2 pt 12 15
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For selective control of annual grasses that are actively growing, before tillering, and not stressed for moisture. Can be used as banded, broadcast, or spot treatments. Can be sprayed over the top of small nonbearing trees. Repeated applications may be needed on perennial grasses. Add crop oil concentrate or methylated seed oil for best performance; ammonium sulfate or ammonium nitrate will enhance activity on some grass weeds.
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.
‡ 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 these two intervals is the minimum time that must elapse before harvest may occur.
# Acceptable for use on organically grown produce
— Information not available
* Permit required from county agricultural commissioner for purchase or use.
Text Updated: 08/17
Treatment Table Updated: 08/17
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