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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Citrus

Herbicide Treatment Table

(Reviewed 9/08, updated 9/08)

In this Guideline: More about weeds in citrus:
Common name   R.E.I.+ P.H.I.+
(trade name) Amount/Acre (hours) (days)
When choosing a pesticide, consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
BEFORE PLANTING
Preemergence
A. TRIFLURALIN 0.5–1 lb a.i.    
  (Treflan)   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: 2–12 months.
 
Postemergence
A. GLYPHOSATE 1–3.8 lb a.i.    
  (Roundup, etc.)   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 1 lb a.i./acre in 10–40 gal water. Apply to young annuals or vigorously growing perennials in flowering stage. Some perennials require the 3.8 lb a.i./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./year.
 
B. FLUAZIFOP-P-BUTYL 0.125–0.375 lb a.i.    
  (Fusilade DX)   12 NA
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Apply to actively growing grasses when they are 2–8 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. CLETHODIM 0.073–0.12125 lb a.i.    
  (Select Max)   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.
 
NEWLY PLANTED ORCHARDS (nonbearing trees)
Preemergence
A. ISOXABEN 0.66–0.9975 lb a.i.    
  (Gallery T & V)   12 1 year
  WSSA MODE OF ACTION GROUP NUMBER1: 21
  COMMENTS: 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.
 
B. NAPROPAMIDE 4 lb a.i.    
  (Devrinol) 50DF   12 35
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Apply to the soil surface in 20–60 gal water/acre. Must be incorporated within 7 days of application or sprinkler irrigated. Needs to be combined with a postemergent herbicide if weeds have emerged. Residual period: 4–10 months. Residual control reduced under frequent, low-volume drip or microsprinkler irrigation.
 
C. ORYZALIN 2–6 lb a.i. 24 NA
  (Surflan)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Apply to the soil surface in 20–60 gal water/acre. If rain does not occur within 21 days after application, sprinkle irrigate with 0.5–2 inches water. May be combined with a postemergent 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.
 
D. OXYFLUORFEN 1.2–2 lb a.i. 24 1 year
  (Goal 2XL)
  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 3–4 weeks after application for effective incorporation and control. Do not disturb soil following treatment or poor control will result. Residual period 4-10 months.
   
E. PENDIMETHALIN 2–3.96 lb a.i. 24 1 year
  (Prowl EC)    
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: For use in nonbearing citrus only. Treatments are most effective when adequate rainfall or irrigation is received within 21 days after 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.
 
F. EPTC 2.1–3 lb a.i. 12 1 year
  (Eptam) 7E
  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).
 
G. FLUMIOXAZIN 0.188-0.376 lb a.i. 12 1 year
  (Chateau)
  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 postemergent herbicides. It will not provide adequate control of emerged weeds unless mixed with a postemergent herbicide. Residual period: 3-6 months.
 
Postemergence
A. CARFENTRAZONE 0.024–0.031 lb a.i. 12 3
  (Shark)      
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Use no more than 0.124 lb a.i./acre/season. A spray adjuvant is required, and ammonium sulfate added at 10-15 lb/100 gal may improve control. Ph of spray solution should be 5-8. Apply to weeds less than 4 inches tall. Control is improved during warm, dry weather. Use nozzles and procedures that provide thorough weed coverage.
 
B. CLETHODIM 0.09–0.12125 lb a.i. 24 1 year
  (Select Max)
  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.
 
C. DIQUAT 0.375–0.5 lb a.i. 24 1 year
  (Reglone)
  WSSA MODE OF ACTION GROUP NUMBER1: 22
  COMMENTS: Add a non-ionic surfactant at 0.25% v/v. Apply in 20-60 gal 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. 12 1 year
  (Fusilade DX)
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: For use in nonbearing citrus only. Apply to actively growing grasses when they are 2–8 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.
 
E. GLYPHOSATE 0.5–4 lb a.i. 4 NA
  (Roundup, etc.)
  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 1 lb/acre in 10–40 gal water. Apply to young annuals or vigorously growing perennials in flowering stage. Some perennials require the 4 lb/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.
 
F. MSMA 1.99 lb a.i. 12 0
  WSSA MODE OF ACTION GROUP NUMBER1: 17
  COMMENTS: Apply to trees no more than 1 year old. Apply to yellow nutsedge with fewer than 5 leaves in 60 gal water/acre. Multiple applications may be needed. Air temperature around 85°F is best for maximum activity.
 
G. OXYFLUORFEN 0.5–1 lb a.i. 24 1 year
  (Goal 2XL)
  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.
 
H. PARAQUAT* 0.3–0.9 lb a.i. 24 0
  (Gramoxone Inteon)
  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).
 
I. SETHOXYDIM 0.28–0.46875 lb a.i. 12 15
  (Poast)
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Apply to actively growing grasses that are 2–8 inches tall. Controls annual grasses (except annual bluegrass, bromes, and fescues) that are actually growing and not water stressed. Use Dash HC spray adjuvant at 1 pt/acre or crop oil concentrate at 2 pt/acre. Do not apply more than 1.875 lb a.i./season.
 
ESTABLISHED ORCHARD
Preemergence
A. BROMACIL 3.2–6.4 lb a.i. 12 0
  (Hyvar)
  WSSA MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: Use low rates on sand and loamy sand soils. Rates of 4–4.8 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 40–50% 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. Do not use in the Imperial, Coachella, or Palo Verde valleys.
 
B. DIURON 2.4–3.2 lb a.i. 12 0
  (Karmex DF, Direx)
  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 40–50% of the total applied in fall and the remainder applied in spring. Do not apply more than 3.2 lb a.i./season. Diuron is sometimes combined with other preemergent 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: 8–12 months.
 
C. NAPROPAMIDE 4 lb a.i. 12 35
  (Devrinol) 50DF
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Apply to the soil surface in 20–60 gal water/acre. Must be incorporated within 7 days after application or sprinkler irrigated. Needs to be combined with a postemergent herbicide if weeds have emerged. Residual period: 4–10 months. Residual control reduced under frequent, low-volume drip or microsprinkler irrigation.
 
D. NORFLURAZON 1–3.93 lb a.i. 12 30
  (Solicam DF)
  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 nutsedge populations. Residual period: 6–12 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.
 
E. ORYZALIN 2–6 lb a.i. 24 0
  (Surflan)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Apply to the soil surface in 20–60 gal water/acre. If rain does not occur within 21 days after application, sprinkle irrigate with 0.5–2 inches of water. May be combined with a postemergent 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.
 
F. SIMAZINE 2–4 lb a.i. 12 0
  (Princep)
  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 1 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 preemergent herbicides. On light soils, simazine often is used at rates of 0.5–1 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. Do not use in the Imperial, Coachella, or Palo Verde valleys. Residual period: 8–12 months.
 
G. THIAZOPYR 0.5–1 lb a.i. 12 90
  (Visor) 2E
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: For grapefruit and orange only. Apply to the soil during winter. For best control of nutsedge species apply in early to midwinter. Residual period is 5–8 months.
 
H. TRIFLURALIN 0.5–1 lb a.i. 12 0
  (Treflan, etc.)
  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 0.024–0.031 lb a.i. 12 3
  (Shark) 0.5–2 lb    
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Use no more than 0.124 lb a.i./acre/season. A spray adjuvant is required and ammonium sulfate added at 10-15 lb/100 gal may improve control. Ph of spray solution should be 5-8. Apply to weeds less than 4 inches tall. Control is improved during warm, dry weather. Use nozzles and procedures that provide thorough weed coverage.
 
B. GLYPHOSATE 0.5–4 lb a.i. 4 1
  (Roundup, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: Avoid application to open 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.
 
C. PARAQUAT* 0.3–0.9 lb a.i. 24 0
  (Gramoxone Inteon)
  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).
 
D. SETHOXYDIM 0.28–0.46875 lb a.i. 12 15
  (Poast)
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Apply when grasses are less than 4 inches tall. Controls annual grasses (except annual bluegrass, bromes, and fescues) that are actually growing and not water stressed. Do not apply more than 1.875 lb a.i./acre/season.
 
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) 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. For more information, see http://www.hracglobal.com.
NA Not applicable.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Citrus
UC ANR Publication 3441
Weeds
A. Shrestha, UC IPM Program, Kearney Agricultural Center, Parlier
N. V. O'Connell, UC Cooperative Extension, Tulare County
Acknowledgment for contributions to Weeds:
T. S. Prather, Department of Plant, Soil and Entomological Sciences (PSES), University of Idaho
D. W. Cudney, Botany and Plant Sciences, UC Riverside

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