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How to Manage Pests

UC Pest Management Guidelines


Prune

Herbicide Treatment Table

(Reviewed 6/06, updated 12/09)

In this Guideline: More about weeds in prune:

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

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to environmental impact Not all registered pesticides are listed. Always read label of product being used.
 
PREPLANT
Preemergent (before weeds germinate)
A. TRIFLURALIN 0.5–1 lb a.i. 12 0
  (Treflan, Trilin)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Broadcast preplant in 5 to 40 gallons of water per acre. Trifluralin must be incorporated immediately after application to avoid loss of activity. Plant tree roots below treated soil. Do not place treated soil near roots during planting. Controls many annuals and is helpful in suppressing perennial weeds. Residual period: 2–12 months.
 
Postemergent (after weeds emerge)
A. GLYPHOSATE 1–4 lb a.i. 4 17
  (Roundup UltraMax)
  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 3–10 gal water. 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 significantly 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 4 lb/acre rate for control. May be used on young weeds in the planting row followed by planting into the dead weeds. As a result of the no-till effect, new weeds usually do not establish for a month or more. Do not use more than 10.6 lb/year.
 
NEWLY PLANTED ORCHARDS (nonbearing trees)
Preemergent
A. ISOXABEN 0.5–1 lb a.i. 12 365
  (Gallery T&V)
  WSSA MODE OF ACTION GROUP NUMBER1: 21
  COMMENTS: 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.
 
B. TRIFLURALIN 1–2 lb a.i. 12 0
  (Treflan, Trilin etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergent selective herbicide for annual grasses. Apply prebloom by ground as a directed spray and mechanically incorporate, taking care not to injure the trees with the incorporation. Must be incorporated immediately after application to avoid loss of activity. Used on new plantings or established orchards as a strip treatment. Suppresses bermudagrass, johnsongrass, and dallisgrass rhizomes. Only one application per year. Residual period: 2–12 months.
 
C. ORYZALIN 2–6 lb a.i. 24 0
  (Surflan, Farm Saver Oryzalin 4 A.S. etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergent selective herbicide for annual grasses. Apply to the soil surface in 20–40 gal water/acre. 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. Most effect on annual grasses and numerous broadleaf annuals. Very safe for young or newly planted trees and on sandy or sandy loam soils. Used to maintain control in strips down the row. The higher rates give the longest soil residual. Usually used at 4 lb a.i./acre. Residual period: 4–10 months.
 
D. NAPROPAMIDE 4 lb a.i. 12 35
  (Devrinol 50DF)
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Use being dropped from the label. Read label carefully to be sure that the crop is listed on the label of the product used. Apply to the soil surface in 20–60 gal water/acre. Use only once per season. Must be incorporated within either mechanically or with sprinkler irrigation or rainfall within 21 days of application between November and February or within 24 hours the remainder of the year. Effective on annual grasses and several annual broadleaves. Effective in maintaining weed-free strips down the row. Needs to be combined with a postemergent herbicide if weeds have emerged. Residual period: 4–10 months.
 
E. PENDIMETHALIN 2–4 lb a.i. 24 60
  (Prowl H2O)
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Apply in 10 or more gal water/acre to soil under trees. 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 7 days. Will not control emerged weeds. Residual period: 4–10 months
 
F. THIAZOPYR 0.5–1 lb a.i. 12 1 year
  (Visor)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: For use on nonbearing trees only; Use allowed under a SLN registration. Apply in 20 or more gal water/acre. Provides nutsedge and mare's tail suppression on coarse textured soils with low organic matter. Best control is achieved when irrigation or rainfall occurs within 7 days of application. Will not control emerged weeds. Residual period: 4-10 months.
 
G. RIMSULFURON 0.03 lb a.i. 4 7
  (Matrix FNV)
  WSSA MODE OF ACTION GROUP NUMBER1: 2
  COMMENTS: For use on nonbearing and bearing trees. Apply in 10 or more gal water/acre to soil under trees. Apply only to trees that have been established for one full growing season. Best control is achieved when irrigation or rainfall occurs within 2 weeks after application. When band applications are made, treating 50% or less of an orchard, a second application can be made. Will not control emerged weeds. Residual period: 4–10 months.
 
H. FLUMIOXAZIN 0.188–0.376 lb a.i. 12 60
  (Chateau SW)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: For use on dormant nonbearing and bearing trees established for 1 year or more. 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. Use allowed under a supplemental label. Residual period: 3-6 months.
 
Postemergent
A. CLETHODIM 0.09–0.124 lb a.i. 24 1 year
  (SelectMax)
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: For use on dormant nonbearing and bearing trees established for 1 year or more. 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. Use allowed under a supplemental label. Residual period: 3–6 months.
 
B. SETHOXYDIM 0.19–0.47 lb a.i. 12 1 year
  (Poast)
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: For use on nonbearing trees only. Apply to young perennial grasses. Repeat applications will be required for the control of perennial grasses. Add 2 pt/acre of a nonphytotoxic crop oil concentrate to the spray solution. Residual period: less than one month.
 
C. MSMA 2-4 lb a.i. 12 1 year
  (MSMA 6 Plus etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 17
  COMMENTS: For use on nonbearing trees only. Apply in 50 gallons of water per acre to insure adequate coverage. Can be applied up to three times per year. Apply as a directed spray or in such a way as to avoid contact with the foliage of prunes.
 
D. CARFENTRAZONE 0.008–0.031 lb a.i. 12 3 day
  (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 treatments as new growth occurs, but they must be at least 14 days apart. Do not use more than 0.124 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.
 
ESTABLISHED ORCHARDS
Preemergent
A. TRIFLURALIN 1–2 lb a.i. 12 0
  (Treflan, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergent selective herbicide for annual grasses. Apply prebloom by ground as a directed spray and mechanically incorporate, taking care not to injure the tree. Must be incorporated immediately after application to avoid loss of activity. Frequently used as a strip treatment. Suppresses bermudagrass, johnsongrass, and dalligrass rhizomes. Only one application per year. Residual period: 2–12 months.
 
B. ORYZALIN 2–6 lb a.i. 24 0
  (Surflan, Farm Saver, Oryzalin 4 A.S. etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Apply to the soil surface in 20–40 gal water/acre. If rain does not occur within 21 days, sprinkle irrigate with 0.5–2 inches of water. Most effect on annual grasses and numerous broadleaf annuals. Very safe for sandy or sandy loam soils. Used to maintain control in strips down the row. 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. Residual period: 4–10 months.
   
C. NAPROPAMIDE 4 lb a.i. 12 35
  (Devrinol 50DF)
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Use being dropped from the label. Read label carefully to be sure that the crop is listed on the label of the product used. Apply to the soil surface in 20–60 gal water/acre. Use only once per season. Must be incorporated within either mechanically or with sprinkler irrigation or rainfall, within 21 days of application between November and February, or within 24 hours the remainder of the year. Effective on annual grasses and several annual broadleaves. Effective in maintaining weed-free strips down the row. Needs to be combined with a postemergent herbicide if weeds have emerged. Residual period: 4–10 months.
 
D. NORFLURAZON 1.97–3.93 lb a.i. 12 60
  (Solicam DF)
  WSSA MODE OF ACTION GROUP NUMBER1: 12
  COMMENTS: Similar to oryzalin but is effective on more annual broadleaf and grass species. Can suppress yellow nutsedge or bermudagrass when used year after year. Apply to soil as a directed spray from fall to early spring under trees established for at least 2 years. If no rainfall occurs within 4 weeks, incorporate with sprinkler or flood irrigation. Remove existing weeds with cultivation or a postemergent herbicide, because it has no postemergent activity. Avoid higher rates on sandy or gravelly soils to prevent 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.
 
E. OXYFLUORFEN 0.5–2.0 lb a.i. 24 0
  (GoalTender)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: For use on dormant trees only. Apply following harvest up to February 15 (February 1 in the Coachella Valley). Apply by ground one time per season in 40–100 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. Effective as a pre- and postemergent herbicide. Effective on little mallow (cheeseweed). Useful combined with other postemergent herbicides, such as glyphosate, or in combination with preemergent herbicides, such as oryzalin, simazine, or thiazopyr. Check label for use period. Residual period: 4–10 months.
 
F. PRONAMIDE 1–4 lb a.i. 24 0
  (Kerb)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Do not apply to trees less than 1 year old. Selective herbicide for control of winter annual and perennial grasses. Apply in fall after fruit harvest. Apply in 40-50 gal water/acre to the soil at the base of the trees. Must be applied before weed emergence because it will not control emerged weeds. Rainfall or irrigation is essential after application for effective weed control. Residual period: 4-8 months.
 
G. RIMSULFURON 0.03 lb a.i. 4 7
  (Matrix FNV)
  WSSA MODE OF ACTION GROUP NUMBER1: 2
  COMMENTS: For use on nonbearing and bearing trees. Apply in 10 or more gal water/acre to soil under trees. Apply only to trees that have been established for one full growing season. Best control is achieved when irrigation or rainfall occurs within 2 weeks after application. When band applications are made, treating 50% or less of an orchard, a second application can be made. Will not control emerged weeds. Residual period: 4–10 months.
 
H. FLUMIOXAZIN 0.188–0.376 lb a.i. 12 60
  (Chateau SW)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: For use on dormant nonbearing and bearing trees established for 1 year or more. 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. Use allowed under a supplemental label. Residual period: 3–6 months.
 
I. PENDIMETHALIN 2–4 lb a.i. 24 60
  (Prowl H20)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Apply in 10 or more gal water/acre to soil under trees. 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 7 days. Will not control emerged weeds. Residual period: 4–10 months.
 
Postemergent
A. GLYPHOSATE 1–4 lb a.i. 4 17
  (Roundup, Touchdown, etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: Apply with controlled droplet application or with low-pressure, flat-fan nozzles. For annual weed control, use 1 lb a.i./acre in 3–10 gal water. 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. For chemical mowing, consult label for exact timing and rates, depending on weed size and species. Apply to young annuals or vigorously growing perennials. Some perennials require the 4 lb a.i./acre rate for control. A good herbicide for perennial weeds, but doesn't eradicate field bindweed or nutsedge. Not effective on some broadleaf weeds at older stages of growth (little mallow and filaree). Avoid drift onto green bark or foliage of tree or injury will result. It is important to monitor treated areas for escaped weeds, as glyphosate resistant weeds have been observed in orchards where glyphosate has been used repeatedly for several years.
 
B. PARAQUAT* 0.625–1.0 lb a.i. 12 0
  (Gramoxone Inteon)
  WSSA MODE OF ACTION GROUP NUMBER1: 22
  COMMENTS: Nonselective postemergent, contact herbicide used for quick top kill of most weed species. Less effective against perennials that will regrow (bermudagrass, dallisgrass, johnsongrass and field bindweed). Most effective when used in late winter or early spring on small annual grass species in combination with preemergent herbicides. Apply in 10–60 gal water/acre to young weeds. Use 0.25% volume per volume nonionic surfactant or 1.0% volume per volume of a crop oil concentrate. Repeat treatment as new growth occurs. A restricted use pesticide.
 
C. OXYFLUORFEN 0.5–2.0 lb a.i. 24 0
  (GoalTender)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Dormant application to young (4-leaf-stage) weeds. Effective on little mallow (cheeseweed) and filaree. Useful combined with glyphosate or oryzalin. May be combined with other postemergent herbicides for specific weeds. Apply following harvest up to February 15 (February 1 in the Coachella Valley). Apply by ground one time per season in 40–100 gal water/acre on firm soil. Must not be mechanically disturbed or poor weed control will result. Effective as a pre-and postemergent herbicide. Residual period: 4–10 months.
 
D. 2,4–D* 1–1.4 lb acid equivalent 48 40
  (Orchard Master etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 4
  COMMENTS: For use on established trees one year or older. Effective on most broadleaf annual weeds. Provides partial control of field bindweed. Apply as a directed spray to weeds, using low-pressure, flooding nozzles between the tree rows. Best results are obtained when applied a few days after an irrigation. Do not allow drift onto the trees or injury may result. No more than two applications allowed during the growing season. Residual period: 4–6 weeks.
 
E. FLUAZIFOP-P-BUTYL 0.125–0.375 lb a.i. 12 14
  (Fusilade DX)
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: For control of annual and perennial grass weeds. A crop oil concentrate at 0.5 to 1% volume per volume or a nonionic surfactant at 0.25 to 0.5% volume per volume must be added to the spray solution. Diammonium phosphate (10-34-0) can also be added to the spray solution to improve control in areas with hard water. Add the diammonium phosphate to the water before adding the herbicide and surfactant. Avoid contact of spray with foliage of trees. Apply in 5-40 gal water, with spray pressures of 30 to 60 psi. Best results are obtained when applied within 7 days after irrigation. Do not apply to grass that is stressed or poor control may result. Repeat applications may be required for johnsongrass and bermudagrass. Residual period: less than 1 month.
 
F. CARFENTRAZONE 0.008–0.031 lb a.i. 12 3 day
  (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 treatments as new growth occurs, but they must be at least 14 days apart. Do not use more than 0.124 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
  NOTE: Combinations are most often used to broaden the weed control spectrum. At the rates recommended below, perennial weeds will not be controlled. Other combinations can be used depending upon the weed spectrum present in the orchard.
A. GLYPHOSATE 0.5–1 lb a.i. 4 17
  (Roundup etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  . . . PLUS . . .
  OXYFLUORFEN 0.1–1 lb a.i. 24 0
  (GoalTender)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: For broad-spectrum control of emerged weeds. Apply in a minimum of 10 gal water/acre in dormant trees. Helps increase control of cheeseweed, filaree, chickweed, and grasses. Glyphosate effectiveness is increased with low-water volume and oxyfluorfen is more effective at the higher volume. Avoid drift and follow directions for application period of oxyfluorfen.
 
B. GLYPHOSATE 0.5–1 lb a.i. 4 17
  (Roundup etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  . . . PLUS . . .
  ORYZALIN 4 lb a.i. 24 0
  (Surflan etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  . . . or . . .
  NAPROPAMIDE 4 lb a.i. 12 35
  (Devrinol 50DF)
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Use being dropped from the Devrinol label. Read label carefully to be sure that the crop is listed on the label of the product used. Combines pre- and postemergent control of most annual weeds with residual up to 6 months. Combination choice depends on weed spectrum and how rapid incorporation will occur. Napropamide needs irrigation within 7 days, oryzalin within 21 days. Apply post-directed to small seedlings when cotton is at least 8 inches tall.
 
C. ORYZALIN 4 lb a.i. 24 0
  (Surflan etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  . . . PLUS . . .
  OXYFLUORFEN 2 lb a.i. 24 0
  (GoalTender)
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Combined to give broad-spectrum control. Apply preemergence or combined with paraquat or glyphosate if weeds have emerged. Irrigate within 21 days if rain has not occurred.
 
D. GLYPHOSATE 0.5 lb a.i. 4 17
  (Roundup etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  . . . PLUS . . .
  2,4–D* 0.5 lb a.i. 48 40
  (Orchard Master CA etc.)
  WSSA MODE OF ACTION GROUP NUMBER1: 4
  . . . PLUS . . .
  SURFACTANT 0.5–1%  
  COMMENTS: Combined to give broad-spectrum control. Apply postemergence to young, growing weeds. Avoid drift or contact with leaves.
 
+ 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.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Prune
UC ANR Publication 3464
Weeds
W. T. Lanini, Weed Science/Plant Sciences, UC Davis
F. J. A. Niederholzer, UC Cooperative Extension, Sutter/Yuba counties
Acknowledgment for contributions Weeds:
A. Shrestha, UC IPM Program, Kearney Agricultural Center, Parlier

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