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How to Manage Pests

UC Pest Management Guidelines


Avocado

Herbicide Treatment Table

(Reviewed 1/07, updated 8/08)

In this Guideline: More about weeds in avocado:

Common name Amount/Acre R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
When choosing an herbicide, consider the environmental impact.

SITE PREPARATION
Before Weeds Emerge
A. SIMAZINE
2–4 lb a.i.
12
  (Princep)
  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. 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. Do not use in the Imperial, Coachella, or Palo Verde valleys. Residual period: 8-12 months.
   
B. NORFLURAZON
Label rate
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 postemergent herbicide) because it has no postemergent 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.
   
Established Weeds
A. GLYPHOSATE
  (Roundup)
0.5–4 lb a.i.
see label
see label
  (Touchdown)
See label
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 perennials in flowering stage. 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 rate
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 postemergent herbicide, because it has no postemergent 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.
 
Established Weeds
A. GLYPHOSATE
  (Roundup)
0.5–4 lb a.i.
see label
see label
  (Touchdown)
See label
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 perennials in flowering stage. 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.
   
B. SETHOXYDIM
0.28–0.46 lb a.i.
12
365
  (Poast)    
  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.
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
A. Shrestha, UC Statewide IPM Program, Kearney Agricultural Center, Parlier
W. T. Lanini, Weed Science/Plant Sciences, UC Davis
C. A. Wilen, UC Statewide IPM Program, San Diego County
P. A. Phillips, UC IPM Program, UC Cooperative Extension, Ventura County

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