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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Olive

Herbicide Treatment Table

(Reviewed 1/08, updated 1/08)

In this Guideline: More about weeds in olive:
Herbicide Amount/Acre R.E.I.+ P.H.I.+
(trade name)   (hours) (days)
 
When choosing a pesticide, consider information relating to environmental impact.
 
SITE PREPARATION
Established weeds
A. GLYPHOSATE
  (Roundup, etc.) 0.5–4 lb a.i. 12 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 10–40 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 7–14 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 10.6 lb a.i./acre/year.
  . . . or . . .
  (Touchdown) 1–3.75 lb a.i. 12 17
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: For annual weed control use 1 lb when weeds are less than 12 inches in height. For perennial weeds use 1.5–3.75 lb in 10–30 gal water/acre. Use flat fan nozzles at 30–50 psi, not flood jets. A nonionic surfactant may be used up to 0.25% volume per volume.
 
B. PARAQUAT* 0.625–1 lb a.i. 12 0
  (Gramoxone Inteon)
  WSSA MODE OF ACTION GROUP NUMBER1: 22
  COMMENTS: Apply in 20–60 gal water/acre to young weeds. Use 0.5% nonionic surfactant. Repeat treatment as new growth occurs.
 
AFTER PLANTING
Before weeds emerge
Note: Whenever tank mixes are used, 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. 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 postemergent herbicides. It will not provide adequate control of emerged weeds, unless mixed with a postemergent herbicide. Residual period: 3-6 months.
 
B. ISOXABEN 0.5–0.9975 lb a.i. 12 365
  (Gallery T&V)
  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 postemergent 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.
 
C. ORYZALIN 2–6 lb a.i 24 0
  (Surflan AS)
  (FarmSaver)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Nonbearing and bearing trees. Apply to the surface in 20–60 gal water/acre. Best if irrigated after application or applied before rainfall. If rain does not occur within 21 days, sprinkle irrigate with 0.5–2 inches of water. May be combined with a postemergent herbicide if weeds are present. The higher label rate give the longest soil residual. Usually used at 4 lb a.i./acre. Residual period: 6–12 months.
 
D. NAPROPAMIDE 4 lb a.i. 12 35
  (Devrinol 50 DF)
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Nonbearing and bearing trees. Apply to the surface in 20–60 gal water/acre. Must be incorporated within 7 days of application or sprinkler irrigated. A second application of 4 lb can be made during any one growing season. May be combined with a postemergent herbicide if weeds have emerged. Residual period: 4–10 months
 
E. OXYFLUORFEN 1–2 lb a.i. 24 0
  (Goal)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Nonbearing and bearing trees. Apply in 20–60 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. Residual period 4–10 months
 
F. 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 3 years of age. Do not apply more than 3.2 lb a.i./acre/season. Diuron is sometimes combined with other preemergent 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/rate adjustments; do not use on soils with less than 1% organic matter. Residual period: 8–12 months.
 
G. 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 older than 3 years anytime between harvest and early spring. Make only 1 application/year. 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/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. If simazine has been found in groundwater in your area, your orchard may be in a designated pesticide Monitoring Zone (PMZ), and there may be restrictions on its use. Residual period: 8–12 months.
 
Established weeds
A. GLYPHOSATE
  (Roundup, Roundup Ultra) 0.5­4 lb a.i. see label 17
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: Rates vary depending on the formulation used. Apply with controlled droplet applicator or with low pressure flat fan nozzles. For annual weed control, use 1 lb/acre in 10–40 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 7–14 days after treatment for maximum control.
  . . . or . . .
  (Touchdown) 1–3.75 lb a.i. 12 17
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: For annual weed control use 1 lb a.i. when weeds are less than 12 inches in height. For perennial weeds use 1.5–3.75 lb a.i. in 10–30 gal water/acre. Use flat fan nozzles at 30–50 psi, not flood jets. Do not apply more than 4 lb a.i./acre/year. Do not apply within the year when a crop will be harvested. Avoid drift onto green bark or foliage or injury will result.
 
B. PARAQUAT* 0.625–1 lb a.i. 12 13
  (Gramoxone Inteon)
  WSSA MODE OF ACTION GROUP NUMBER1: 22
  COMMENTS: Apply in 20–60 gal water/acre to young weeds. Use 0.5% nonionic surfactant. Repeat treatment as new growth occurs. Do not exceed 4 postemergent directed applications/season.
 
C. OXYFLUORFEN 0.5–1 lb a.i. 24 0
  (Goal)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Dormant application to young (4-leaf stage) weeds. May be combined with other postemergent herbicides for specific weeds.
 
D. FLUAZIFOP-P-BUTYL 0.25–0.375 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 2–8 inches tall but before tillering and/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.
 
E. 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.
 
F. CLETHODIM 0.0954–0.2496 lb a.i. 24 365
  (Prism)
  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.
 
G. CARFENTRAZONE 0.008-0.031 lb a.i. 12 3
  (Shark)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: A postemergent, 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/season. Use 0.25% volume per volume nonionic surfactant, 1.0% volume per volume of a crop oil concentrate, or a silicone or MSO surfactant.
 
Herbicide combinations
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. GLYPHOSATE 0.5–1 lb a.i. in 20–40 gal water/acre 12 17
  (Roundup, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  . . . PLUS . . .
  OXYFLUORFEN 0.1–1 lb a.i. 24 0
  (Goal)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: For broad-spectrum control of emerged weeds in olives. Helps increase control of little mallow (cheeseweed), filaree, chickweed, and grasses. The effectiveness of glyphosate is increased with low water volume; oxyfluorfen is more effective at the higher volume. Avoid drift and follow directions for application period of oxyfluorfen. 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.
 
B. GLYPHOSATE 1 lb a.i. see label see label
  (Roundup, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  . . . PLUS . . .
  ORYZALIN 4 lb a.i. 24 0
  (Surflan AS)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  . . . or . . .
  NAPROPAMIDE 4 lb a.i. 12 35
  (Devrinol 50 DF)
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Combines post- and preemergent control of most annual weeds with residual control up to 6 months. Combination choice depends on weed spectrum and how rapid incorporation will occur following application. Napropamide needs irrigation within 7 days, oryzalin within 21 days. 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.
 
C. PARAQUAT* 0.625 lb a.i. 12 13
  (Gramoxone Inteon)
  WSSA MODE OF ACTION GROUP NUMBER1: 22
  . . . PLUS . . .
  OXYFLUORFEN 0.5–1 lb a.i. 24 0
  (Goal)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Broad-spectrum postemergent control. Avoid drift and follow directions for application period of oxyfluorfen. 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.
 
D. ORYZALIN 4 lb a.i. 24 0
  (Surflan AS)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  . . . PLUS . . .
  OXYFLUORFEN 1 lb a.i. 24 0
  (Goal)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Combined to give broad-spectrum control. Applied preemergence or combined with paraquat or glyphosate if weeds have emerged. Activate within 21 days. 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.
 
E. SIMAZINE 1–2 lb a.i. 12 0
  (Princep, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 5
  . . . PLUS . . .
  DIURON 1–1.6 lb a.i. 12 0
  (Karmex)
  WSSA MODE OF ACTION GROUP NUMBER1: 7
  . . . PLUS . . .
  GLYPHOSATE 1 lb a.i. 12 17
  (Roundup, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: This combination is effective on a broad range of weed species. Add glyphosate only when weeds have emerged and are actively growing. Use lower rates of simazine and diuron on light soils and high rates on heavy, fine-textured soils. Residual period for diuron and simazine: 8–12 months. Glyphosate has no biological residual. 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.
 
 
+  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/.
* 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
W. T. Lanini, Weed Science/Plant Sciences, UC Davis
Acknowledgment for contributions to the weed section:
C. L. Elmore, Vegetable Crops/Weed Science, UC Davis
D. W. Cudney, Botany and Plant Sciences, UC Riverside
D. R. Donaldson, UC Cooperative Extension, Napa Co.

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