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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Nectarine

Herbicide Treatment Table

(Reviewed 6/06, updated 9/06)

In this Guideline: More about weeds in peach:
Herbicide Amount/Acre P.H.I.+
(trade name)   (days)
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.  
  (Treflan)
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  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.
 
B. PENDIMETHALIN 2–4 lb a.i.  
  (Prowl) 3.3EC  
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  COMMENTS: 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.
 
Postemergent (after weeds emerge)
A. GLYPHOSATE 1–4 lb a.i.  
  (Roundup UltraMax)    
  ...OR...    
  (Touchdown) 1–3.75 lb a.i.  
  MODE OF ACTION: A glycine (Group 9)1 herbicide.
  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.  
  (Gallery T&V)    
  MODE OF ACTION: A benzamide (Group 21)1 herbicide.
  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.  
  (Treflan, Trilin 5 etc.)    
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  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.  
  (Surflan, Oryzalin 4 A.S. etc.)    
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  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.  
  (Devrinol) 50DF    
  MODE OF ACTION: An acetamide (Group 15)1 herbicide.
  COMMENTS: Apply to the soil surface in 20–60 gal water/acre. Use only once per season. Must be incorporated 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.  
  (Prowl) 3.3 EC    
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  COMMENTS: For use on dormant nonbearing trees only. 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
  (Visor) 2E 0.5-1 lb a.i. 1 year
  MODE OF ACTION: A pyridine (Group 3)1 herbicide.
  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. FLUMIOXAZIN
  (Chateau SW) 0.188-0.376 lb a.i. 1 year
  MODE OF ACTION: An N-phenylphthalimide (Group 14)1 herbicide.
  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. Use allowed under a supplemental label. Residual period: 3–6 months
 
Postemergent
H. CLETHODIM
  (Prism) 0.095-0.125 lb a.i. 1 year
  MODE OF ACTION: A DIM (Group 1)1 herbicide.
  COMMENTS: For use on nonbearing trees only. Apply to young 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.
 
I. SETHOXYDIM 0.19–0.47 lb a.i. 25 days
  (Poast)    
  MODE OF ACTION: A DIM (Group 1)1 herbicide.
  COMMENTS: 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.
 
J. MSMA 2-4 lb a.i. 1 year
  (MSMA 6 Plus etc.)    
  MODE OF ACTION: An organoarsenical (Group 17)1 herbicide.
  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 nectarines.
 
K. CARFENTRAZONE 0.008–0.031 lb a.i. 3 day
  (Shark)    
  MODE OF ACTION: A triazolinone (Group 14)1 herbicide.
  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. 60
  (Treflan, etc.)
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  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. 0
  (Surflan, Oryzalin 4 A.S. etc.)    
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  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. 35
  (Devrinol 50DF)    
  MODE OF ACTION: An acetamide (Group 15)1 herbicide.
  COMMENTS: Apply to the soil surface in 20–60 gal water/acre. Use only once per season. Must be incorporated 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. 60
  (Solicam DF)    
  MODE OF ACTION: A pyridazinone (Group 12)1 herbicide.
  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.  
  (Goal 2 XL etc.)    
  MODE OF ACTION: A diphenylether (Group 14)1 herbicide.
  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.  
  (Kerb)    
  MODE OF ACTION: A benzamide (Group 3)1 herbicide.
  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. DIURON 1.6–4 lb a.i. 8 months
  (Karmex, Dinex, Diuron)    
  MODE OF ACTION: A urea (Group 7)1 herbicide.
  COMMENTS: Apply to the soil under trees at least 3 years of age. A single application may be made in winter or split between fall and spring. Diuron is sometimes combined with other preemergent herbicides to broaden spectrum of weeds controlled. These combination treatments frequently use lower rates of diuron. Adjust rates according to soil texture. Do not use on soils with less than 1% organic matter. Considered to be a ground water contaminant and requires a use permit within Ground Water Protection Areas. Residual period: 8-12 months.
 
H. SIMAZINE 1–2 lb a.i.  
  (Princep Caliber 90)    
  MODE OF ACTION: A triazine (Group 5)1 herbicide.
  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 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. Residual period: 8-12 months.
 
POSTEMERGENT
A. GLYPHOSATE 1–4 lb a.i. 17
  (Roundup UltraMax)    
  ...OR...    
  (Touchdown) 1–3.75 lb a.i.  
  MODE OF ACTION: A glycine (Group 9)1 herbicide.
  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. 14
  (Gramoxone Max)    
  MODE OF ACTION: A bipyridylium (Group 22)1 herbicide.
  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. Do not exceed 3 applications/season.
 
C. OXYFLUORFEN 0.5–2.0 lb a.i.  
  (Goal 2 XL etc.)    
  MODE OF ACTION: A diphenylether (Group 14)1 herbicide.
  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* 0.95-1.425 lb a.i. 40
  (Orchard Master etc.)    
  MODE OF ACTION: A phenoxy-carboxylic-acid (Group 4)1 herbicide.
  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. 14
  (Fusilade DX)    
  MODE OF ACTION: An FOP (Group 1)1 herbicide.
  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. Apply to johnsongrass when it is between 8 to 18 inches in height. Repeat applications may be required for johnsongrass and bermudagrass. Residual period: less than 1 month.
 
F. CARFENTRAZONE 0.008–0.031 lb a.i. 3 day
  (Shark)    
  MODE OF ACTION: A triazolinone (Group 14)1 herbicide.
  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. 17
  (Roundup, Touchdown, etc.)    
  MODE OF ACTION: A glycine (Group 9)1 herbicide.
  ...PLUS...    
  OXYFLUORFEN 0.1–1 lb a.i.  
  (Goal 2XL, etc.)    
  MODE OF ACTION: A diphenylether (Group 14)1 herbicide.
  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. 17
  (Roundup, Touchdown, etc.)    
  MODE OF ACTION: A glycine (Group 9)1 herbicide.
  ...PLUS...    
  ORYZALIN 4 lb a.i.  
  (Surflan, etc.)    
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  ...OR...    
  NAPROPAMIDE 4 lb a.i.  
  (Devrinol 50DF)    
  MODE OF ACTION: An acetamide (Group 15)1 herbicide.
  COMMENTS: 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.
 
C. ORYZALIN 4 lb a.i.  
  (Surflan, etc.)    
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  ...PLUS...
  OXYFLUORFEN 2 lb a.i.  
  (Goal 2XL, etc.)    
  MODE OF ACTION: A diphenylether (Group 14)1 herbicide.
  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. 40
  (Roundup, Touchdown, etc.)    
  MODE OF ACTION: A glycine (Group 9)1 herbicide.
  ...PLUS...
  2,4–D* 0.5 lb a.i.  
  (Orchard Master CA, etc.)    
  MODE OF ACTION: A phenoxy-carboxylic-acid (Group 4)1 herbicide.
  ...PLUS...
  SURFACTANT 0.5–1%  
  COMMENTS: Combined to give broad-spectrum control. Apply postemergence to young, growing weeds. Avoid drift or contact with leaves.
 
 
+  Preharvest interval. Do not apply within this many days of 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.plantprotection.org/HRAC/.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Nectarine
UC ANR Publication 3451
Weeds
A. Shrestha, UC IPM Program, Kearney Agricultural Center, Parlier
W. T. Lanini, Weed Science/Plant Sciences, UC Davis
K. Hembree, UC Cooperative Extension, Fresno County

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