Olive

Agricultural pest management


Herbicide Treatment Table

(Reviewed 3/14, updated 3/14)

In this Guideline: More about weeds in olive:

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

  Calculate impact of pesticide on air quality
The following 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
Established weeds
 
A. GLYPHOSATE
  (Roundup PowerMax, Touchdown Total, etc.) 0.8–3.7 lb a.e. See label 17
  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 to 40 gal water/acre with 1 lb/acre. 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 to 14 days after treatment to obtain maximum control. New weeds usually do not establish for a month or more, due to the no-till effect. Do not use more than 9.62 lb a.i./acre per year. Addition of ammonium sulfate at 15 lbs/100 gallons of spray solution will generally improve weed control by reducing the effects of hard water. Add ammonium sulfate to the water in the spray tank prior to adding glyphosate.
 
B. PARAQUAT* 0.625–1 lb a.i. 24 13
  (Gramoxone Inteon)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 22
  COMMENTS: A non-selective, postemergence herbicide used for quick top kill of most weed species. Apply in 20 to 60 gal water/acre to young weeds. Use 0.5% nonionic surfactant. Repeat treatment as new growth occurs.
 
AFTER PLANTING
Before weeds emerge
 
Note: Combinations are most often used to broaden the weed control spectrum. Perennial weeds will not be controlled with these combinations. Other combinations can be used depending upon the weed spectrum present in the orchard. For tank mixes, observe all directions for use on all labels, and employ the most restrictive limits and precautions. Never exceed the maximum a.i. on any label when tank mixing products that contain the same a.i
 
A. DIURON 1.6 + 1.6 lb a.i. 12 0
  (Karmex, Direx)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 7
  COMMENTS: Make a split application in fall and spring. Direct spray to the soil under trees at least one year of age. Diuron is sometimes combined with other preemergence herbicides to broaden spectrum of weeds controlled. These combination treatments frequently use lower rates of diuron. Do not apply to tree trunks less than 1.5 inches in diameter. Note: Pay special attention to soil texture and rate adjustments; do not use on soils with less than 1% organic matter. A permit is required from the county agricultural commissioner for use in groundwater protection areas. Residual period: 8–12 months.
 
B. FLUMIOXAZIN 0.188–0.376 lb a.i. 12 365
  (Chateau SW)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: For use on dormant nonbearing trees only. Apply in 10 or more gal water/acre to soil under trees when completely dormant. Do not apply on newly planted trees unless soil is firm and there are no cracks in soil around base of trees. Best control is achieved when irrigation or rainfall occurs within 21 days. 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. 12 14
  (Alion)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 29
  COMMENTS: For use on trees established for at least three years and exhibiting normal growth and vigor. Do not use on soils with more than 20% gravel content. Controls broadleaf and grass weeds at germination; will not control emerged weeds. For best activation, rainfall or irrigation within 21 days of application is needed. Residual period: 4–10 months.
 
D. ISOXABEN 0.5–1.0 lb a.i. 12 See label
  (Gallery 75)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 21
  COMMENTS: For use on nonbearing trees only. Wait until soil has settled around newly planted trees before applying. Controls broadleaf weeds only before they have germinated; will not control emerged weeds. If weeds are emerged, lightly cultivate or add a postemergence herbicide. Requires incorporation for activation, either by light cultivation (1 to 2 inches) or rainfall (minimum of 0.5 inches) within 21 days after application. Sprinkler or flood irrigation can also be used for incorporation. Apply in at least 10 gal/acre of water.
 
E. ORYZALIN 2–6 lb a.i 24 0
  (Surflan AS)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Nonbearing and bearing trees. Apply to the surface in 20 to 60 gal water/acre. Best if irrigated after application or applied before rainfall. If rain does not occur within 21 days, sprinkle irrigate with 0.5 to 2 inches of water. Effective against annual grasses and several annual broadleaves. It should be combined with a postemergence herbicide if weeds are present. The higher label rate gives the longest soil residual. Usually used at 4 lb a.i./acre. Residual period: 6–12 months.
 
F. OXYFLUORFEN 1–2 lb a.i. 24 0
  (GoalTender)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: Nonbearing and bearing trees. Apply in 20 to 60 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. Often combined with oryzalin. Check label for use period, cut-off dates, and restrictions. Certain oxyfluorfen formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations of oxyfluorfen. Residual period 4–10 months.
 
G. PENDIMETHALIN 1.9–3.8 lb a.i. 24 60
  (Prowl H2O)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Nonbearing and bearing trees. Apply by ground in 10 or more gal water/acre. Best if irrigated after application or applied before rainfall. Can be applied via chemigation, or flood, flooded basin, or gravity-flow irrigation systems. Do not apply over the top of trees with leaves, buds, or fruit. Do not apply to newly planted nursery stock. Do not apply more than 4 lb a.i. per year. Combine with a postemergence herbicide if weeds are present.
 
H. SIMAZINE* 2–3.96 lb a.i. 12 0
  (Princep 4L, Princep Caliber 90, etc.)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Apply to the soil under trees one year or older anytime between harvest and early spring. Make only one application per year. 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/acre. Do not use on gravel, sand, or loamy sand soils. If irrigation is applied immediately after application, limit water to 0.5 inch. A permit is required from the county agricultural commissioner for use in groundwater protection areas. Residual period: 8–12 months.
 
Established weeds
 
A. CARFENTRAZONE 0.008-0.031 lb a.i. 12 3
  (Shark)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: A postemergence contact herbicide used for quick top kill of most broadleaf weed species. Can be applied anytime during the season, but if fruit are present, it should either be avoided or applied with extreme care to avoid drift. It can also be used for sucker control. Apply in a minimum of 20 gal water/acre to weeds less than 6 inches tall. Repeat treatment as new growth occurs; do not apply at less than a 14-day interval. Do not use more than 0.096 lb a.i./acre per season. Use 0.25% volume per volume nonionic surfactant, 1.0% volume per volume of a crop oil concentrate, or a silicone or methylated seed oil (MSO) surfactant.
 
B. CLETHODIM 0.1–0.12 lb a.i. 24 365
  (Select Max)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: For use on nonbearing trees only. Apply to rapidly growing grasses when they have reached the height recommended on label. Do not apply to drought stressed plants. Use a crop oil concentrate. Do not apply within 1 year of harvest.
 
C. FLUAZIFOP-P-BUTYL maximum 0.187 lb a.i. 12 365
  (Fusilade DX)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: For use on nonbearing trees only. For selective control of grasses when they are 2 to 8 inches tall but before tillering or heading. Use a crop oil (1%) or nonionic surfactant (0.25%) to increase penetration and control. Do not apply to grass that is stressed or poor control may result.
 
D. GLYPHOSATE
  (Roundup Weathermax) 0.8–3.7 lb a.e. 4 17
  WSSA MODE-OF-ACTION GROUP NUMBER1: 9
  COMMENTS: Rates vary depending on the formulation used, weed species present, and weed size. Apply with controlled droplet applicator or with low pressure flat fan nozzles. For annual weed control, use 1 lb/acre in 10 to 40 gal water. For chemical mowing, consult label for exact timing and rates depending on weed size and species. Apply to young annuals or vigorous growing perennials. Avoid drift onto green bark or foliage, or injury will result. Weeds should not be cultivated for 7 to 14 days after treatment for maximum control.
 
E. OXYFLUORFEN 0.5–1 lb a.i. 24 0
  (GoalTender)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: Dormant application to young (4-leaf stage) weeds. May be combined with other postemergence herbicides for specific weeds. Certain oxyfluorfen formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations of oxyfluorfen. Residual period 4–10 months.
 
F. PARAQUAT* 0.625–1 lb a.i. 24 13
  (Gramoxone Inteon)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 22
  COMMENTS: Apply in 20 to 60 gal water/acre to young weeds. Use 0.5% nonionic surfactant. Repeat treatment as new growth occurs. Do not exceed 4 postemergence directed applications per season.
 
G. PYRAFLUFEN-ETHYL 0.0013–0.0053 lb a.i. 12 0
  (Venue)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: For postemergence control of some broadleaf weeds in bearing and non-bearing olives. Apply in a minimum of 20 gal/acre. Do not exceed more than 3 applications per year. Residual period: none.
 
H. SETHOXYDIM 0.28–0.46 lb a.i. 12 365
  (Poast)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: For control of annual and perennial grasses in 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 R.E.I. exceeds the P.H.I. 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.hracglobal.com.
* Permit required from county agricultural commissioner for purchase or use.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Olive
UC ANR Publication 3452

Weeds

B. D. Hanson, Weed Science and Plant Sciences, UC Davis
Acknowledgment for contributions to Weeds:
C. L. Elmore, Weed Science and Plant Sciences, UC Davis
D. W. Cudney, Botany and Plant Sciences, UC Riverside
D. R. Donaldson, UC Cooperative Extension, Napa County
W. T. Lanini, Weed Science and Plant Sciences, UC Davis

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