Agriculture: Citrus Pest Management Guidelines

Herbicide Treatment Table

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.
 
BEFORE PLANTING
Preemergence
 
A. TRIFLURALIN 0.5–1 lb a.i.
(Treflan) 1–2 pt 12 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: Broadcast preplant incorporated. Plant tree roots below treated soil. Do not place treated soil near roots during planting. Controls many annuals and is helpful on perennial weeds. Useful for helping eradicate johnsongrass before planting. Residual period: 2 to 12 months.
 
Postemergence
 
A. CLETHODIM 0.073–0.12125 lb a.i.
(Select Max) 9.6–16 fl oz 24 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: Apply to actively growing grasses. Use lower rate for barnyardgrass, foxtails, and panicums before grasses are over 4 inches tall. Use medium rate for crabgrasses before they are over 4 inches tall. Use higher rates (0.096–0.12125 lb a.i./acre) for goosegrass, lovegrass, ryegrass, and sprangletop before grasses are over 6 inches tall.
 
B. FLUAZIFOP-P-BUTYL 0.125–0.375 lb a.i.
(Fusilade DX) 8–24 fl oz 12 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: Apply to actively growing grasses when they are 2 to 8 inches in height. Use lower rates for smaller grasses. 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.
 
C. GLUFOSINATE 0.88–1.5 lb a.i.
(Rely 280) 48–82 fl oz 12 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 10
COMMENTS: Herbicide works best when weeds are actively growing. Warm temperatures, high humidity, and bright sunlight improve the performance. Weed control may be reduced when applications are made to weeds under stress due to drought or cool temperatures. Weeds under stress or in dense populations will require application at the highest rate recommended. Requires uniform thorough spray coverage. Avoid contact with green bark, stems, or foliage, as injury may occur. This herbicide is a glutamine synthetase inhibitor; weed population may have a higher chance of developing resistance after repeated use.
 
D. GLYPHOSATE 0.77–3.71 lb a.e.
(Roundup Powermax) 0.7–3.3 qt 4 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Apply with a controlled applicator or with low-pressure flat fan nozzles. For annual weed control use the lower end of the rate range in 10 to 40 gal water. Apply to young annuals or vigorously growing perennials in flowering stage. Some perennials require the maximum per acre rate for control. May be used on young weeds in strip followed by planting into the dead weeds. New weeds usually do not establish for a month or more because of the no-till effect. Do not use more than 9.625 lb a.i. per year.
 
NEWLY PLANTED ORCHARDS (NONBEARING TREES)
Preemergence
 
A. EPTC 3.06–6.12 lb a.i.    
(Eptam 7E) 3.5–7 pt 12 15
WSSA MODE-OF-ACTION GROUP NUMBER1: 8
COMMENTS: For use on nonbearing orange, grapefruit, and lemon. Immediately incorporate herbicide with tree hoes or rotary hoes. Provides short-term residual control (4–6 weeks).
 
B. FLUMIOXAZIN 0.188–0.376 lb a.i.    
(Chateau SW) 6–12 oz 12 365 (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. Do not make a sequential application within 30 days of the first application. Can be mixed with other pre- or postemergence herbicides. It will not provide adequate control of emerged weeds unless mixed with a postemergence herbicide. Residual period: 3–6 months.
 
C. INDAZIFLAM 0.065–0.085 lb a.i.    
(Alion) 5–6.5 fl oz 12 7
WSSA MODE-OF-ACTION GROUP NUMBER1: 29
COMMENTS: Do not apply to trees established less than one year. Best control is achieved when irrigation or rainfall follows within 21 days of application. Can be mixed with other pre- or postemergence herbicides. It will not provide control of emerged weeds unless mixed with a postemergence herbicide. Needs to be combined with another preemergence herbicide if weed seeds have already sprouted at time of herbicide applciation. Residual period: 4–6 months.
 
D. ISOXABEN 0.5–1.0 lb a.i.
(Trellis) 0.66-1.33 lb 12 365 (1 year)
WSSA MODE-OF-ACTION GROUP NUMBER1: 21
COMMENTS: For use in nonbearing lemon, grapefruit, and orange groves only. Wait until soil has settled around transplant to apply. Requires irrigation to activate unless 0.5 inches of rain has fallen within 21 days after application. Used only where broadleaf weeds are expected; does not control grasses or nutsedges. Apply in at least 10 gal/acre of water.
 
E. MESOTRIONE 0.094–0.188 lb a.i.
(Broadworks) 3–6 fl oz 12 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 27
COMMENTS: Can be applied in citrus trees less than 12 months old that are exhibiting normal growth and vigor. Dry conditions following application may reduce the preemergence activity. If an activating rain (0.25 inches) is not received within 7 to 10 days after application, rotary hoeing is suggested to activate herbicide. To avoid crop injury, apply spray to grove floor avoiding contact with crop foliage, stems, or fruit. Always ensure that agitation is maintained until spraying is complete. Mesotrione is not effective for most grass weeds, however it can be tank mixed with other registered herbicides to provide a broad spectrum of weed control (see label). Do not exceed three applications per year (12-month period).
F. ORYZALIN 2–6 lb a.i.    
(Surflan AS) 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: 4–10 months.
G. OXYFLUORFEN 1.5 lb a.i.
(Goal 2XL) 6 pt 24 365 (1 year)
(Goaltender) 3 pt 24 365 (1 year)
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: For use on nonbearing citrus only. Apply to the soil surface. At least 0.25 inches water must be received within 3 to 4 weeks after application for effective incorporation and control. Do not disturb soil following an herbicide application or poor control will result. Residual period 4 to 10 months. 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, 2020. Review the Department of Pesticide Regulation's updated fact sheet.
H. PENDIMETHALIN 2–3.96 lb a.i. (Prowl EC)
1.9–5.98 lb a.i. (Prowl H2O)
(Prowl EC) 2.4–4.8 qt 24 365 (1 year)
(Prowl H2O) 2.0–6.3 qt 24 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: For Prowl 3.3 EC, use in nonbearing citrus only. Herbicide applications are most effective when adequate rainfall or irrigation is received within 21 days after the application. Do not apply to newly transplanted trees until ground has settled and no cracks are present. Contact with leaves, shoots, or buds may deform plant tissue.
 
I. RIMSULFURON 0.03125–0.0625 lb a.i.
(Matrix) 2–4 oz 4 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Apply only to crops that have been established for one full growing season and are in good health and vigor. Apply to young active weeds and use a spray adjuvant for best control. Apply as a uniform broadcast application to the orchard floor as a uniform band application directed at the base of the trunk. Avoid direct spray contact with crop foliage or fruit, except undesirable suckers. Rainfall or irrigation is needed for herbicide activation. For improved weed management, should be applied in tank mixture with other registered preemergence herbicides and when soil is moist at the time of application. Do not apply by air.
Postemergence
 
A. CARFENTRAZONE 0.008–0.032 lb a.i.    
(Shark EW) 0.5–2 fl oz 12 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Use no more than 0.124 lb a.i./acre per season. A spray adjuvant is required, and ammonium sulfate added at 10 to 15 lb per 100 gal may improve control. The pH of spray solution should be 5 to 8. Apply to weeds less than 4 inches tall. Control is improved during warm, dry weather. Use nozzles and procedures that provide thorough weed coverage. Avoid drift, as this product is active at a very low rate.
 
B. CLETHODIM 0.09–0.12125 lb a.i.    
(Select Max) 11.8–16 fl oz 24 365 (1 year)
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For use in nonbearing citrus only. Apply to actively growing grasses. Use lower rate for barnyardgrass, foxtails, and panicums before grasses are over 4 inches tall. Use medium rate for crabgrasses before they are over 4 inches tall. Use higher rates (0.12125 lb a.i./acre) for goosegrass, lovegrass, ryegrass, and sprangletop before grasses are over 6 inches tall. Dusty or water-stressed plants will not be well-controlled.
 
C. DIQUAT 0.375–0.5 lb a.i.    
(Reglone) 1.5–2 pt 24 365 (1 year)
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Add a non-ionic surfactant at 0.25% v/v. Apply in 20 to 60gal water/acre with thorough weed coverage to weeds less than 4 inches tall. Control is improved during warm, dry weather.
 
D. FLUAZIFOP-P-BUTYL 0.25–0.375 lb a.i.    
(Fusilade DX) 16–24 fl oz 12 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: For use in nonbearing citrus only. Apply to actively growing grasses when they are 2 to 8 inches in height. Use lower rates for smaller grasses. 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 the boot stage. Dusty or water-stressed plants will not be well-controlled.
 
E. GLUFOSINATE 0.88–1.5 lb a.i.
(Rely 280) 48–82 fl oz 12 14
WSSA MODE-OF-ACTION GROUP NUMBER1: 10
COMMENTS: Herbicide works best when weeds are actively growing. Warm temperatures, high humidity, and bright sunlight improve the performance. Weed control may be reduced when applications are made to weeds under stress due to drought or cool temperatures. Weeds under stress or in dense populations will require application at the highest rate recommended. Requires uniform thorough spray coverage. Avoid contact with green bark, stems, or foliage, as injury may occur. Herbicide is a glutamine synthetase inhibitor; weed population may have a higher chance of developing resistance after repeated use.
 
F. GLYPHOSATE 0.77–3.71 lb a.e.    
(Roundup Powermax) 0.7–3.3 qt 4 NA
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Apply with a controlled applicator or with low-pressure, flat fan nozzles. For annual weed control use the lower end of the rate range in 10 to 40 gal water. Apply to young annuals or vigorously growing perennials in flowering stage. Some perennials require the maximum per acre rate for control. May be used on young weeds in strip followed by planting into the dead weeds. New weeds usually do not establish for a month or more because of the no-till effect. Hairy fleabane and horseweed can be controlled if in seedling stage. Do not use more than 9.625 lb a.i./year.
 
G. MESOTRIONE 0.094–0.188 lb a.i.
(Broadworks) 3–6 fl oz 12 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 27
COMMENTS: Apply to actively growing weeds. Can be applied in citrus trees less than 12 months old that are exhibiting normal growth and vigor. To avoid crop injury, apply spray to grove floor avoiding contact with crop foliage, stems, or fruit. Always ensure that agitation is maintained until spraying is complete. Mesotrione is not effective for most grass weeds, however it can be tank mixed with other registered herbicides to provide a broad spectrum of weed control (see label). Do not exceed three applications per year (12-month period). Complete weed death may take up to 2 weeks.
 
H. OXYFLUORFEN 0.5–1.5 lb a.i.
(Goal 2XL) 2–6 pt 24 365 (1 year)
(Goaltender) 1–3 pt 24 365 (1 year)
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: For use in nonbearing citrus only. Apply to weeds under 4 inches tall. If grasses and some broadleaf weeds are present, mix with paraquat or glyphosate. 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, 2020. Review the Department of Pesticide Regulation's updated fact sheet.
 
I. PARAQUAT* 0.625–1 lb a.i.    
(Gramoxone SL 2.0) 2.5–4 pt 24 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Apply when weeds are less than 4 inches tall. Repeat applications as new growth occurs. Do not apply directly to foliage or trunk of tree. For protection, use tree wraps around trunk. Use a nonionic surfactant at 0.5% volume by volume (v/v).
 
J. RIMSULFURON 0.03125–0.0625 lb a.i.
(Matrix) 2–4 oz 4 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Apply only to crops that have been established for one full growing season and are in good health and vigor. Apply to young active weeds and use a spray adjuvant for best control. Apply as a uniform broadcast application to the orchard floor as a uniform band application directed at the base of the trunk. Avoid direct spray contact with crop foliage or fruit, except undesirable suckers. Rainfall or irrigation is needed for herbicide activation. For improved weed management, apply in tank mixture with other registered postemergence herbicides and when soil is moist at the time of application. Do not apply by air.
 
K. SAFLUFENACIL 0.04 lb a.i.    
(Treevix) 0.9 oz 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Do not apply to trees established less than one year. Apply when weeds are less than 4 inches tall. Can be applied up to three times per season. Do not apply directly to foliage or trunk of tree. For protection, use tree wraps around trunk. Use a methylated seed oil adjuvant at 1% volume by volume (v/v).
 
L. SETHOXYDIM 0.28–0.46875 lb a.i.    
(Poast) 1.5–2.5 pt 12 15
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: Apply to actively growing grasses that are 2 to 8 inches tall. Controls annual grasses (except annual bluegrass, bromes, and fescues) that are actually growing and not water stressed. Use an appropriate crop oil concentrate or methylated seed oil surfactant. Do not apply more than 1.875 lb a.i. per season. Dusty or water-stressed plants will not be well-controlled.
 
ESTABLISHED ORCHARD
Preemergence
 
A. BROMACIL 3.2–6.4 lb a.i.    
(Hyvar X) 4–8 lb 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 5
COMMENTS: Use low rates on sand and loamy sand soils. Rates of 4 to 4.8 lb a.i./acre can be applied to sandy loam soils and higher rates to silt loam and clay loam soils. Split application and apply 40 to 50% of the total herbicide in fall with the remainder in spring just before weeds emerge or soon after weed emergence. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. If bromacil has been found in groundwater in your area, your area may be designated a Pesticide Monitoring Zone (PMZ), and there may be restrictions on its use.
 
B. BROMACIL/DIURON 2.4–4.8 lb a.i.    
(Krovar I DF) 3–6 lb 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 5/7
COMMENTS: Do not apply to trees established less than 3 years of age. Use low rates on sand and loamy sand soils. Split application and apply 2.4 to 3.2 lb a.i. in fall followed by 1.6- to 3.2 lb a.i. in spring just before weeds emerge or soon after weed emergence. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. If bromacil has been found in groundwater in your area, your area may be designated a Pesticide Monitoring Zone (PMZ), and there may be restrictions on its use.
 
C. DIURON 2.4–3.2 lb a.i.    
(Karmex DF) 3–4 lb 12 0
(Direx) 2.4–3.2 qt 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 7
COMMENTS: Direct to the soil under trees that are at least 3 years of age. A split application can be made with 40 to 50% of the total applied in fall and the remainder applied in spring. Do not apply more than 3.2 lb a.i. per season. Diuron is sometimes combined with other preemergence herbicides to broaden the spectrum of weeds controlled. These combination treatments frequently use lower rates of diuron. Do not use on soils with less than 1% organic matter. Do not use in Imperial, Coachella or Palo Verde valleys. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. If diuron has been found in groundwater in your area, your area may be designated a Pesticide Monitoring Zone (PMZ), and there may be restrictions on its use. Residual period: 8 to 12 months.
 
D. FLAZASULFURON 0.033–0.044 lb a.i.    
(Mission) 2.1–2.8 oz 12 1
COMMENTS: Not labeled for use on grapefruit. Direct to the soil under trees that are at least 5 years of age. A split application can be made at either the low or high label rate after at least a 3 month re-treatment interval. Do not apply more than 0.09 lb a.i. per season. Flazisulfuron is usually combined with other preemergence herbicides to broaden the spectrum of weeds controlled. Do not use on soils with more than 85% sand content. Residual period: 8 to 12 months.
 
E. INDAZIFLAM 0.065–0.085 lb a.i.    
(Alion) 5–6.5 fl oz 12 7
WSSA MODE-OF-ACTION GROUP NUMBER1: 29
COMMENTS: Do not apply to trees established less than one year. Best control is achieved when irrigation or rainfall follows within 21 days of application. Can be mixed with other pre- or postemergence herbicides. It will not provide control of emerged weeds unless mixed with a postemergence herbicide. Needs to be combined with another preemergence herbicide if weed seeds have already sprouted at the time of the herbicide application. Residual period: 4 to 6 months.
 
F. MESOTRIONE 0.094–0.188 lb a.i.
(Broadworks) 3–6 fl oz 12 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 27
COMMENTS: Can be applied in citrus trees less than 12 months old that are exhibiting normal growth and vigor. Dry conditions following application may reduce the preemergence activity. If an activating rain (0.25 inches) is not received within 7 to 10 days after application, rotary hoeing is suggested to activate herbicide. To avoid crop injury, apply spray to grove floor avoiding contact with crop foliage, stems, or fruit. Always ensure that agitation is maintained until spraying is complete. It is not effective for most grass weeds, however can be tank mixed with other registered herbicides to provide a broad spectrum of weed control (see label). Do not exceed three applications per year (12 month period). Mesotrione also has postemergence activity on small annual broadleaf weeds (see postemergence herbicides below).
 
G. NORFLURAZON 1.965–3.93 lb a.i.
(Solicam DF) 2.5–5 lb 12 30
WSSA MODE-OF-ACTION GROUP NUMBER1: 12
COMMENTS: Apply to soil as a directed spray from fall to early spring under trees established for at least 2 years. Apply in at least 20 gal water/acre. Chemigation with norflurazon is possible in citrus, see label for instructions. Can help reduce low to moderate numbers of nutsedge. Residual period: 6 to 12 months. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. If norflurazon has been found in groundwater in your area, your area may be designated a Pesticide Monitoring Zone (PMZ), and there may be restrictions on its use. Do not use in the Imperial, Coachella, or Palo Verde valleys.
 
H. ORYZALIN 2–6 lb a.i.
(Surflan AS) 2–6 qt 24 0
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.
 
I. PENDIMETHALIN 2–6 lb a.i.
(Prowl H2O) 2.1–4.2 qt 24 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: For use in nonbearing and bearing citrus. Herbicide applications are most effective when adequate rainfall or irrigation is received within 21 days after application. Contact with leaves, shoots, or buds may deform plant tissue.
 
J. RIMSULFURON 0.03125–0.0625 lb a.i.
(Matrix) 2–4 oz 4 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Apply only to crops that have been established for one full growing season and are in good health and vigor. Apply to young active weeds and use a spray adjuvant for best control. Apply as a uniform broadcast application to the orchard floor as a uniform band application directed at the base of the trunk. Avoid direct spray contact with crop foliage or fruit, except undesirable suckers. Rainfall or irrigation is needed for herbicide activation. For improved weed management, apply in tank mixture with other registered preemergence herbicides and when soil is moist at the time of application. Do not apply by air.
 
K. SIMAZINE 2–4 lb a.i.
(Princep 4L) 2–4 qt 12 See label
WSSA MODE-OF-ACTION GROUP NUMBER1: 5
COMMENTS: For use in grapefruit, lemon, and orange groves. Apply to the soil under trees older than 1 year. Make one application per year or split the application between fall and spring. Use the high rate for heavy soils. Simazine is frequently used in combination with other preemergence herbicides. On light soils, simazine often is used at rates of 0.5 to 1 lb a.i./acre. 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. If simazine has been found in groundwater in your area, your area may be designated a Pesticide Monitoring Zone (PMZ), and there may be restrictions on its use. Residual period: 8 to 12 months.
 
L. TRIFLURALIN 0.5–1 lb a.i.    
(Treflan HFP) 1–2 pt 12 0
WSSA MODE-OF-ACTION GROUP NUMBER1: 3
COMMENTS: For use in nonbearing and bearing orchards. Apply as a directed spray and mechanically incorporate, taking care not to injure the tree. Residual period: 2–12 months.
 
Postemergence
 
A. CARFENTRAZONE 0.008–0.032 lb a.i.    
(Shark EW) 0.5–2 fl oz 12 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 14
COMMENTS: Use no more than 0.124 lb a.i./acre per season. A spray adjuvant is required, and ammonium sulfate added at 10 to 15 lb per 100 gal spray solution may improve control. The pH of spray solution should be 5 to 8. Apply to weeds less than 4 inches tall. Control is improved during warm, dry weather. Use nozzles and procedures that provide thorough weed coverage but avoid drift. Very effective on mallow plants.
 
B. GLUFOSINATE 0.88–1.5 lb a.i.
(Rely 280) 48–82 fl oz 12 14
WSSA MODE-OF-ACTION GROUP NUMBER1: 10
COMMENTS: Herbicide works best when weeds are actively growing. Warm temperatures, high humidity, and bright sunlight improve the performance. Weed control may be reduced when applications are made to weeds under stress due to drought or cool temperatures. Weeds under stress or in dense populations will require application at the highest rate recommended. Requires uniform thorough spray coverage. Avoid contact with green bark, stems, or foliage, as injury may occur. Herbicide is a glutamine synthetase inhibitor; weed population may have a higher chance of developing resistance after repeated use.
 
C. GLYPHOSATE 0.77–3.71 lb a.e.
(Roundup Powermax) 0.7–3.3 qt 4 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 9
COMMENTS: Avoid application to open citrus foliage, green, tender wood, or wounds. Do not apply directly to fruit. Glyphosate is effective at low gallonage and is effective applied with a controlled droplet application. See label instructions to use for chemical mowing.
 
D. MESOTRIONE 0.094–0.188 lb a.i.
(Broadworks) 3–6 fl oz 12 1
WSSA MODE-OF-ACTION GROUP NUMBER1: 27
COMMENTS: Apply to actively growing weeds. Can be applied in citrus trees less than 12 months old that are exhibiting normal growth and vigor. To avoid crop injury, apply spray to grove floor, avoiding contact with crop foliage, stems, or fruit. Always ensure that agitation is maintained until spraying is complete. Mesotrione is not effective for most grass weeds, however it can be tank mixed with other registered herbicides to provide a broad spectrum of weed control (see label). Do not exceed three applications per year (12-month period). Complete weed death may take up to 2 weeks.
 
E. PARAQUAT* 0.625–1 lb a.i. 24 0
(Gramoxone SL 2.0) 2.5–4 pt
WSSA MODE-OF-ACTION GROUP NUMBER1: 22
COMMENTS: Do not apply directly to foliage or fruit. Use a nonionic surfactant at 0.5% volume by volume (v/v).
 
F. RIMSULFURON 0.03125–0.0625 lb a.i.
(Matrix) 2–4 oz 4 3
WSSA MODE-OF-ACTION GROUP NUMBER1: 2
COMMENTS: Apply only to crops that have been established for one full growing season and are in good health and vigor. Apply to young active weeds and use a spray adjuvant for best control. . Apply as a uniform broadcast application to the orchard floor as a uniform band application directed at the base of the trunk. Avoid direct spray contact with crop foliage or fruit, except undesirable suckers. Rainfall or irrigation is needed for herbicide activation. For improved weed management, apply in tank mixture with other registered postemergence herbicides and when soil is moist at the time of application. Do not apply by air.
 
G. SETHOXYDIM 0.28–0.46875 lb a.i.    
(Poast) 1.5–2.5 pt 12 15
WSSA MODE-OF-ACTION GROUP NUMBER1: 1
COMMENTS: Apply when grasses are less than 4 inches tall. Controls many annual grasses (annual bluegrass, bromes, and fescues are not controlled) that are actively growing and not water stressed. Do not apply more than 1.875 lb a.i./acre per season.
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.
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.
NA Not applicable.
Text Updated: 04/19
Treatment Table Updated: 04/19