Nectarine

Agricultural pest management


Herbicide Treatment Table

(Reviewed 6/10, updated 6/10, pesticides updated 9/15)

In this Guideline: More about weeds in peach:

Common name Amount per acre REI‡ PHI‡
(Example trade name)   (hours) (days)

UPDATED: 9/15
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.
 
PREPLANT
 
Preemergence (before weeds germinate)
 
A. PENDIMETHALIN 2–3.96 lb a.i.    
  (Prowl H2O) 2-6.3 qt 24 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergence, selective herbicide for annual grasses and some broadleaves. Apply to soil in 10 gal/acre or more before planting and incorporate mechanically 2.5 inches deep. Use untreated soil to fill in around tree roots.
 
B. TRIFLURALIN 0.5–1 lb a.i. 12 NA
  (Treflan HFP)
  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.
 
Postemergence (after weeds emerge)
 
A. GLYPHOSATE
  (Roundup Powermax) 0.387–3.713 lb a.e. 4 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 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 4lb/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 9.625 lb a.i./acre per year.
 
NEWLY PLANTED ORCHARDS (NONBEARING TREES)
 
Preemergence
 
A. FLUMIOXAZIN
  (Chateau SW) 0.188-0.376 lb a.i. 12 60
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: Provides effective control of many annual grasses and broadleaves, including horseweed. 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
 
B. ISOXABEN
  (Gallery T&V) 0.5–0.9975 lb a.i. (0.66–1.33 lb product) 12 365
  (Trellis SC) 0.52–1.008 lb a.i. (16–31 fl oz) 12 365
  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 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.
 
C. ORYZALIN
  (Surflan, Oryzalin 4 A.S.) 2–6 lb a.i. 24 0
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergence selective herbicide for annual grasses and some broadleaves. 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 postemergence 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. PENDIMETHALIN
  (Prowl H2O) 2–3.96 lb a.i. 24 NA
  (Prowl 3.3EC) 2–3.96 lb a.i. 24 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: For use on dormant nonbearing trees only. Selective preemergence herbicide for annual grasses and some broadleaves. 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
 
E. TRIFLURALIN
  (Treflan HFP) See label 12 0
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergence selective herbicide for annual grasses and some broadleaves. 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, depending on rate.
 
Postemergence
 
A. CARFENTRAZONE
  (Shark EW) 0.008–0.025 lb a.i. 12 3 day
  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. Do not exceed 30 psi. Repeat treatments as new growth occurs, but they must be at least 14 days apart. 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 MSO surfactant.
 
B. CLETHODIM
  (Select Max) 0.095–0.12125 lb a.i. 24 365
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: For use on nonbearing trees only. Do not use in Solano County. Apply to young, nonstressed annual or perennial grasses. Repeat applications will be required for the control of perennial grasses. Apply in 5 to 40 gal water/acre. Add 0.25% volume per volume nonionic surfactant to the spray solution. Spray pressure should be between 30 and 60 psi, with higher pressures used when weed density is high. Do not apply a broadleaf herbicide within one day following application or reduced grass control may occur. Residual period: less than one month.
 
C. SETHOXYDIM
  (Poast) 0.19–0.46 lb a.i. 12 25 days
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: Can be applied to trees at all stages of growth. Apply to young nonstressed annual or 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.
 
ESTABLISHED ORCHARDS
 
Preemergence
 
A. FLUMIOXAZIN
  (Chateau SW) 0.188-0.376 lb a.i. 12 60
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: Provides effective control of many annual grasses and broadleaves, including horseweed. 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. Use allowed under a supplemental label. Residual period: 3–6 months
 
B. INDAZIFLAM
  (Alion) 0.045–0.085 lb a.i. 12 14
  WSSA MODE-OF-ACTION GROUP NUMBER1: 29
  COMMENTS: See label for specific rate and soil considerations. Only use in orchards where trees have been established at least three years and are exhibiting normal growth and good vigor. See label for restrictions on use around new replants in established orchards.
 
C. NORFLURAZON*
  (Solicam DF) 1.97–3.93 lb a.i. 12 60
  WSSA MODE-OF-ACTION GROUP NUMBER1: 12
  COMMENTS: 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 postemergence herbicide, because it has no postemergence 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.
 
D. ORYZALIN
  (Surflan, Oryzalin 4 A.S.) 2–6 lb a.i. 24 0
  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 postemergence 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.
 
E. OXYFLUORFEN    
  (GoalTender) 0.5–2 lb a.i. 24 See comments
  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 postemergence herbicide. Effective on little mallow (cheeseweed). Useful combined with other postemergence herbicides, such as glyphosate, or in combination with preemergence herbicides, such as oryzalin or simazine,. Check label for use period. Residual period: 4–10 months. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations.
 
F. PENDIMETHALIN      
  (Prowl H2O) 2–3.96 lb a.i. 24 NA
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Selective preemergence herbicide for annual grasses and some broadleaves. 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.
 
G. PRONAMIDE*    
  (Kerb 50-W) 1–4 lb a.i. 24 NA
  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.
         
H. RIMSULFURON 0.0625 lb a.i. 4 14
  (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.
 
I. SIMAZINE*
  (Princep Caliber 90) 1–1.98 lb a.i. 12 0
  WSSA MODE-OF-ACTION GROUP NUMBER1: 5
  COMMENTS: Apply to the soil under trees older than 3 years. 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 0.5-1.0 lb a.i./acre. Do not use on gravel, sand, or loamy sand soils. If 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. Residual period: 8-12 months.
 
J. TRIFLURALIN
  (Treflan HFP) 1–2 lb a.i. 12 0
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: Preemergence 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 dallisgrass rhizomes. Only one application per year. Residual period: 2–12 months.
 
Postemergence
 
A. CARFENTRAZONE
  (Shark EW) 0.008–0.025 lb a.i. 12 3 day
  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 treatments as new growth occurs, but they must be at least 14 days apart. 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 MSO surfactant.
 
B. FLUAZIFOP-P-BUTYL
  (Fusilade DX) 0.125–0.375 lb a.i. 12 14
  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. Do not apply to grass that is moisture stressed or poor control may result. Apply to johnsongrass when it is between 8 to 18 inches in height. Repeat applications are required for johnsongrass and bermudagrass. Do not graze animals in treated area.
 
C. GLUFOSINATE
  (Rely 280) 0.8–1.5 lbs a.i. 12 14
  WSSA MODE-OF-ACTION GROUP NUMBER1: 10
  COMMENTS: Application rate based on weed size. Only trunks with callused, mature brown bark should be sprayed unless protected from spray contact by nonporous wraps, grow tubes, or waxed containers. Contact with parts of tree other than mature brown bark can result in serious injury. Do not apply within 300 yards of non-dormant pear trees.
 
D. GLYPHOSATE
  (Roundup Powermax) 0.387–3.713 lb a.e. 4 17
  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. Bermudagrass and field bindweed require up to 4 lb a.i./acre rate for control. Persistence is the key for effective control of perennial weeds (i.e. treating every 21 days). Eradication of field bindweed is difficult where roots are deep or tapped into perched water tables. 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.
 
E. OXYFLUORFEN
  (GoalTender) 0.5–2 lb a.i. 24 See comments
  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 postemergence 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 postemergence herbicide. Residual period: 4–10 months. Certain formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations.
 
F. PARAQUAT*
  (Gramoxone SL) 0.625–1 lb a.i. 24 28
  WSSA MODE-OF-ACTION GROUP NUMBER1: 22
  COMMENTS: Nonselective postemergence, contact herbicide used for quick top kill of most weed species. Provides temporary burn down only. 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 preemergence 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. Do not exceed 3 applications per season.
 
G. SETHOXYDIM
  (Poast) 0.19–0.46 lb a.i. 12 25 days
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: Can be applied to trees at all stages of growth. Apply to young nonstressed annual or 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.
 
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) 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.
NA Not applicable.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Nectarine
UC ANR Publication 3451

Weeds

J. A. Roncoroni, UC Cooperative Extension, Napa County
S. D. Wright, UC Cooperative Extension Tulare County

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

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