Avocado

Agricultural pest management


Herbicide Treatment Table

(Reviewed 1/07, updated 8/08, pesticides updated 5/15)

In this Guideline: More about weeds in avocado:

Common name Amount per acre R.E.I.‡ P.H.I.‡
(Example trade name)   (hours) (days)

UPDATED: 5/15
  Calculate impact of pesticide on air quality
 
The following materials are listed alphabetically. When choosing a pesticide, consider information relating to environmental impact, resistance management, the pesticide's properties, and application timing. Not all registered pesticides are listed. Always read the label of the product being used.
 
SITE PREPARATION
Before Weeds Emerge
 
A. NORFLURAZON Label rates 12 60
  (Solicam DF)
  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 20–100 gal water/acre. Residual period: 6–12 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: 4-10 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 20–60 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 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.
 
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 1 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: 8-12 months.
 
Established Weeds
 
A. 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. For annual weed control use 10-40 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 7-14 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.
 
AFTER PLANTING
Before Weeds Emerge
 
A. NORFLURAZON Label rates 12 60
  (Solicam DF)
  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 20–100 gal water/acre. Residual period: 6–12 months.
 
B. 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 20–60 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 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. Can be tank-mixed with glyphosate.
 
Established Weeds
 
A. 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 10-40 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 7-14 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.
 
B. 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 (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.
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. For more information, see http://www.plantprotection.org/HRAC/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Avocado
UC ANR Publication 3436

Weeds

B. A. Faber, UC Cooperative Extension, Santa Barbara/Ventura counties
C. A. Wilen, UC Statewide IPM Program, San Diego County
B. D. Hanson, Plant Sciences, UC Davis

Acknowledgment for contributions to Weeds:
W. T. Lanini, Weed Science/Plant Sciences, UC Davis
A. Shrestha, UC Statewide IPM Program, Kearney Agricultural Center, Parlier
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County

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