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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Pistachio

Herbicide Treatment Table

(Reviewed 2/07, updated 2/07)

In this Guideline: More about weeds in pistachio:
Common name Amount/Acre** R.E.I.+ P.H.I.+
(trade name)   (hours) (days)
When choosing an herbicide, consider information relating to environmental impact.
 
SITE PREPARATION
Established weeds
A. GLYPHOSATE
  (Roundup UltraMax, etc.) 0.5-4 lb a.i. 4 —
  MODE OF ACTION: A glycine (Group 9)1 herbicide.
  COMMENTS: Apply with a ground sprayer with low-pressure, flat fan nozzles or a controlled droplet applicator. Use 10-40 gal water/acre with 1 lb a.i./acre for annual weeds. Add ammonium sulfate at 5-10 lb/100 gal water to improve control. Apply to young, actively growing annual weeds or perennial weeds when flowering. Some perennials may require the higher label rate for control. Application can be made in strips where the trees will be planted into the line of dead weeds. Do not cultivate weeds for 7-14 days after treatment to maximize control.
  ...OR...
  (Touchdown 5) 1-3.75 lb a.i. 12 —
  COMMENTS: Use 1 lb a.i. when susceptible annual weeds are less than 12 inches tall. For perennial weeds, use 1.5-3.75 lb a.i. in 10-30 gal water/acre. Use flat fan nozzles at a low pressure, not flood jets. A nonionic surfactant can be added at 0.25% volume by volume.
 
B. PARAQUAT* 0.3-0.9 lb a.i. 12 —
  (Gramoxone Inteon)  
  MODE OF ACTION: A bipyridylium (Group 22)1 herbicide.
  COMMENTS: Use in 20-60 gal water/acre when weeds are in the seedling stage with good cover of the weed foliage. Add a non-ionic surfactant at 0.5% volume by volume. Repeated applications will be required as new growth occurs.
 
AFTER PLANTING
Before weeds emerge
A. FLUMIOXAZIN 0.188-0.38 lb a.i.    
  (Chateau)   12 60
  MODE OF ACTION: An N-phenylphthalimide (Group 14)1 herbicide.
  COMMENTS: For use in bearing and nonbearing orchards. Apply as a directed spray, avoiding contact with young wood or foliage. Rainfall or irrigation of 0.25 inch needed within 21 to 28 days after treatment for activation. Can be tank-mixed with other preemergent herbicides for broader weed control and with contact herbicides for burndown of weeds already present. Provides about 1 month residual control for each 2 oz/acre product used. Helps provide preemergent control of annual grasses, horseweed, heavy fleabane, and other annual broadleaves.
 
B. ISOXABEN 0.66-1.33 lb a.i.    
  (Gallery T&V)   12 365
  MODE OF ACTION: A benzamide (Group 21)1 herbicide.
  COMMENTS: For use in nonbearing orchards only. It controls broadleaf weeds only. Wait until trees have completely settled into the soil before application. Rainfall or irrigation of at least 0.5 inches should occur within 21 days of treatment to activate herbicide. Apply in at least 10 gal water/acre. Do not use within 1 year of harvest.
 
B. NAPROPAMIDE 4 lb a.i.    
  (Devrinol) 50 DF   12 0
  MODE OF ACTION: An acetamide (Group 15)1 herbicide.
  COMMENTS: For use in bearing and nonbearing orchards. Apply to the soil surface in 20-60 gal water/acre. Must be incorporated by rainfall or sprinkler irrigation within 7 days of treatment. Should be combined with a postemergent herbicide if weeds are present at application. Residual period: 4-10 months. (Residual control reduced under frequent, low-volume drip or microsprinkler irrigation.)
 
C. ORYZALIN 2-6 lb a.i. 24 0
  (Surflan AS, Oryzalin)      
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  COMMENTS: For use in bearing and nonbearing orchards. Apply in 20-60 gal water/acre to soil that is relatively clean of leaves and other debris. If rainfall of 0.25 to 2 inches does not occur within 21 days of treatment, sprinkle irrigate with 0.5-2 inches of water. Often mixed with oxyfluorfen (Goal). Mix with a postemergent herbicide if weeds are present. Usually used at 4 lb a.i. For longer residual control, apply at 6 lb a.i., especially in high rainfall years. Chemigation is allowed-see label for instructions. Residual period: 4-10 months.
 
D. OXYFLUORFEN 1.2-2 lb a.i. 24 0
  (Goal 2XL, etc.)      
  MODE OF ACTION: A diphenylether (Group 14)1 herbicide.
  COMMENTS: For use in bearing and nonbearing orchards. Apply in 20-60 gal water/acre. At least 0.75 inches rainfall or irrigation must be received within 3-4 weeks after treatment. Do not disturb with mechanical equipment or poor weed control will result. Often mixed with oryzalin (Surflan). Refer to the label for use period, cut-off dates, and other restrictions. Residual period: 4-10 months.
 
E. PENDIMETHALIN 2-4 lb a.i. 24 365
  (Prowl 3.3, etc.)      
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  COMMENTS: For use in nonbearing orchards only. Apply in 20-40 gal water/acre to soil surface. Incorporate within 4 days of treatment with rainfall, irrigation, or mechanical incorporation. Directed at base of trees during dormant period, avoiding contact with foliage, or injury may result.
 
F. THIAZOPYR 0.5-1.0 lb a.i. 12 365
  (Visor)
  MODE OF ACTION: A pyridine (Group 3)1 herbicide.
  COMMENTS: Registered for use in nonbearing orchards only under a SLN registration. Applied in 20-40 gal water/acre. Used at lower rates for control of annual weeds. Applied at 0.5 lb a.i. in fall and again in late-winter for yellow nutsedge control. Requires rainfall or irrigation within 21 days following treatment. Can be mixed with oxyfluorfen (Goal) for broader weed control. Residual period: 5-8 months. Do not apply more than 4 pt (1 lb a.i.)/acre/year.
 
Established weeds
A. CLETHODIM 0.09-0.25 lb a.i. 24 365
  (Prism)
  MODE OF ACTION: A DIM (Group 1)1 herbicide.
  COMMENTS: For use in nonbearing orchards only. A crop oil concentrate (1% volume by volume) or nonionic surfactant (0.25% volume by volume) must be added. Used in 20-40 gallons water/acre. For selective control of annual grasses that are actively growing, before tillering, and not stressed for moisture. Repeated applications needed on perennial grasses when their growth meets label requirements.
 
B. DIQUAT 0.375-0.5 lb a.i. 24 365
  (Reglone)
  COMMENTS: For use in nonbearing orchards only. Add a nonionic surfactant at 0.25% v/v. Applied in 20-60 gallons water/acre. Apply when weeds are less than 4 inches tall. Control is improved during warm, dry weather.
 
C. FLUAZIFOP-P-BUTYL 0.25-0.375 lb a.i. 12 365
  (Fusilade DX)
  MODE OF ACTION: An FOP (Group 1)1 herbicide.
  COMMENTS: For use in nonbearing orchards only. A crop oil concentrate (1% volume by volume) or nonionic surfactant (0.25% volume by volume) must be added. Applied in 20-40 gallons water/acre; thorough coverage important. For selective control of annual grasses that are actively growing, before tillering, and not stressed for moisture. Repeated applications needed on perennial grasses when their growth meets label requirements.
 
D. GLYPHOSATE 0.5-4 lb a.i. 4 3
  (Roundup UltraMax, etc.)
  MODE OF ACTION: A glycine (Group 9)1 herbicide.
  COMMENTS: For use in bearing and nonbearing orchards. Apply with a ground sprayer with low-pressure, flat fan nozzles or a controlled droplet applicator. For annual weed control, use 1 lb a.i. in 10–40 gallons water/acre. Adding sprayable ammonium sulfate at 5-10 lb/100 gallons water may improve control. Apply to young, actively growing annual weeds or perennial weeds when flowering. Some perennials may require the higher label rate for control. Avoid drift onto green bark or foliage or injury will result. To maximize control, do not cultivate weeds for 7-14 days after treatment. Can be mixed with low rates of oxyfluorfen (Goal) for broader weed control.
  ...OR...
  (Touchdown 5) 1-3.75 lb a.i. 12 3
  COMMENTS: Use 1 lb a.i. when susceptible annual weeds are less than 12 inches tall. For perennial weeds, use 1.3.75-4 lb a.i. in 10-30 gallons water/acre. Use flat fan nozzles at a low pressure, not flood jets. A nonionic surfactant can be added at to 0.25% volume by volume. Avoid drift onto green bark or foliage or injury will result.
 
E. OXYFLUORFEN 0.5-1 lb a.i. 24 0
  (Goal 2XL, etc.)
  MODE OF ACTION: A diphenylether (Group 14)1 herbicide.
  COMMENTS: For use in bearing and nonbearing orchards. Dormant application to young (4-leaf stage) weeds. May be combined with other postemergent herbicides for specific weeds. Can be applied in-season following bloom (refer to label for specific timing).
 
F. PARAQUAT* 0.3-0.9 lb a.i. 12 7
  (Gramoxone Inteon)
  MODE OF ACTION: A bipyridylium (Group 22)1 herbicide.
  COMMENTS: For use in bearing and nonbearing orchards. Apply in 20-60 gallons water/acre to young, actively growing weeds (less than 4 inches tall). Add a nonionic surfactant at 0.5% volume by volume. Repeat applications will be required as new growth occurs. Do not exceed 2 applications after shells split.
 
G. SETHOXYDIM 0.28-0.47 lb a.i. 12 365
  (Poast)
  MODE OF ACTION: A DIM (Group 1)1 herbicide.
  COMMENTS: For use in nonbearing orchards only. A crop oil concentrate must be added at 1% volume by volume. Used in 20-40 gallons water/acre with thorough spray coverage of the weed foliage. For selective control of annual grasses that are actively growing, before tillering, and not stressed for moisture. Repeat applications needed on perennial grasses when their growth meets label requirements.
 
H. 2,4-D AMINE 1-1.4 lb a.i. 48 60
  (Orchard Master, etc.)
  MODE OF ACTION: A phenoxy-carboxylic-acid (Group 4)1 herbicide.
  COMMENTS: For use in bearing and nonbearing orchards that have been established for at least 1 year. Selective on small, vigorously growing broadleaf weeds. Applications made to sandy soils, under windy conditions, when trees are in bloom, or under hot conditions can result in tree injury. Do not apply before an irrigation or rainfall or injury can result. The sprayer is thoroughly cleaned following treatment as per label recommendations.
 
HERBICIDE TANK-MIX COMBINATIONS
Tank-mix combinations are most often used to broaden the spectrum of weeds controlled. Perennial weeds may not necessarily be controlled with these combinations. Other tank-mix combinations can be used depending on the species present in the orchard.
A. ORYZALIN 4 lb a.i. 12 0
  (Surflan AS, Oryzalin)
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  ....PLUS....
  OXYFLUORFEN 1 lb a.i. 24 0
  (Goal 2XL, etc.)
  MODE OF ACTION: A diphenylether (Group 14)1 herbicide.
  COMMENTS: Combined to give broad-spectrum control. Applied preemergence or combined with glyphosate if weeds have emerged. Activate with rainfall or irrigation within 21 days of treatment.
 
B. NAPROPAMIDE 4 lb a.i. 12 0
  (Devrinol 50 DF)
  MODE OF ACTION: An acetamide (Group 15)1 herbicide.
  ....PLUS....
  OXYFLUORFEN 1 lb a.i. 24 0
  (Goal 2XL, etc.)
  MODE OF ACTION: A diphenylether (Group 14)1 herbicide.
  COMMENTS: Combined to give broad-spectrum control. Rainfall occurs within 7 days. Glyphosate is added if weeds have already emerged.
 
C. GLYPHOSATE 0.5-1 lb a.i. 4 3
  (Roundup UltraMax, etc.)
  MODE OF ACTION: A glycine (Group 9)1 herbicide.
  ....PLUS....
  OXYFLUORFEN 0.1-1 lb a.i. 24 0
  (Goal 2XL, etc.)
  MODE OF ACTION: A diphenylether (Group 14)1 herbicide.
  COMMENTS: Combined for broad-spectrum control of weeds in orchards. Helps increase the control of cheeseweed, filarees, hairy fleabane, horseweed, chickweed, and grasses. Avoid drift onto trees or injury can result. Follow label directions for application period of oxyfluorfen.
 
D. PARAQUAT* 0.5 lb a.i. 12 7
  (Gramoxone Inteon)
  MODE OF ACTION: A bipyridylium (Group 22)1 herbicide.
  ....PLUS....
  ORYZALIN 4 lb a.i. 24 0
  (Surflan AS, Oryzalin)
  MODE OF ACTION: A dinitroaniline (Group 3)1 herbicide.
  COMMENTS: Provides burndown of emerged weeds and preemergent control of annual weeds. Avoid drift onto trees to prevent injury. Emerged weeds must be small for effective control.
 
 
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.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment until harvest may occur. In some cases the R.E.I. exceeds the P.H.I. The longer of these two intervals is the minimum time that must elapse before harvest can take place.
—  Not applicable.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pistachio
UC ANR Publication 3461
Weeds
K. J. Hembree, UC Cooperative Extension, Fresno County
A. Shrestha, UC IPM Program, Kearney Agricultural Center, Parlier

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