Pistachio

Agricultural pest management


Herbicide Treatment Table

(Reviewed 10/14, updated 10/14)

In this Guideline: More about weeds in pistachio:

Herbicide Amount per acre R.E.I.‡ P.H.I.‡
(example trade name)   (hours) (days)
  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.
 
SITE PREPARATION
Established weeds
A. GLYPHOSATE 0.4–3.3 lb a.e. 4
  (Roundup PowerMax) 0.4–3.3 qt 4
  WSSA MODE-OF-ACTION GROUP NUMBER1: 9
  COMMENTS: Apply to young, actively growing annual weeds or perennial weeds when flowering. Some perennials may require the higher label rate for control. Apply with a ground sprayer with low-pressure, flat fan nozzles or a controlled droplet applicator. Use 10 to 40 gal water/acre with 1 lb a.i./acre for annual weeds. Add ammonium sulfate at 5 to 10 lb/100 gal water to improve 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 to 14 days after treatment to maximize control.
  . . . or . . .
  (Touchdown) 1–3.75 lb a.e.; 0.8–3 qt 12
  COMMENTS: Use 1 lb a.i. when susceptible annual weeds are less than 12 inches tall. For perennial weeds, use 1.5 to 3.75 lb a.i. in 10 to 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) 1.2–3.6 pt 12
  WSSA MODE-OF-ACTION GROUP NUMBER1: 22
  COMMENTS: Use in 20 to 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
  (Chateau) 6–12 oz 12 60
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: For use in bearing and nonbearing orchards. Helps provide preemergence control of annual grasses, horseweed, heavy fleabane, and other annual broadleaves. Apply as a directed spray, avoiding contact with young wood or foliage. Rainfall or irrigation of 1/4 inch needed within 21 to 28 days after treatment for activation. Can be tank-mixed with other preemergence herbicides for broader weed control and with contact herbicides for burndown of weeds already present. Residual period: 1 month for each 2 oz/acre product used.
 
B. INDAZIFLAM 0.065–0.085 lb a.i. 12 14
  (Alion)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 29
  COMMENTS: Registered for use in bearing and nonbearing orchards established at least 3 years. Applied in 10 to 30 gal water/acre. Requires rainfall or irrigation within 21 days following treatment. Can be mixed with other preemergence herbicides for broader weed control. 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. Residual period: 5 to 8 months.
 
C. ISOXABEN 0.5–1 lb a.i. 12 60
  (Trellis) 0.66–1.33 lb 12 60
  WSSA MODE-OF-ACTION GROUP NUMBER1: 21
  COMMENTS: For use in bearing and nonbearing orchards. It controls broadleaf weeds only. If annual grasses are expected, mix with another effective herbicide. Rainfall or irrigation of at least 1/2 inch should occur within 21 days of treatment to activate herbicide. Apply in at least 10 gal water/acre. Residual period: 4 to 6 months
 
D. ORYZALIN 2.4–6 lb a.i. 24 0
  (Surflan)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: For use in bearing and nonbearing orchards. Apply in 20 to 40 gal water/acre to soil that is relatively clean of leaves and other debris. If rainfall of 1/2 to 1 inch does not occur within 21 days of treatment, sprinkle irrigate with 1/2 to 2 inches of water. Often mixed with oxyfluorfen. Mix with a postemergence herbicide if weeds are present. 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. 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 to10 months.
 
E. OXYFLUORFEN 1.2–1.5 lb a.i. 24 See comments
  (Goal)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: For use in bearing and nonbearing orchards. Apply between May and 7 days before harvest. Apply in 20 to 60 gal water/acre. At least 3/4 inch rainfall or irrigation must be received within 3 to 4 weeks after treatment. Do not disturb with mechanical equipment or poor weed control will result. Often mixed with oryzalin. Refer to the label for use period, cut-off dates, and other restrictions. 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. Residual period: 4 to 10 months. Certain oxyfluorfen formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations of oxyfluorfen.
 
F. PENDIMETHALIN 3.8–5.985 lb a.i. 24 60
  (Prowl H20)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 3
  COMMENTS: For use in bearing and nonbearing orchards. Apply in 20 to 40 gal water/acre to soil surface. Incorporate within 4 days of treatment with rainfall, irrigation, or mechanical incorporation. Direct at base of trees during dormant period and avoid contact with foliage or injury may result.
 
G. PENOXSULAM + OXYFLUORFEN 0.016–0.031 lb a.i. (penoxsulam)
+ 0.74–1.47 lb a.i. (oxyfluorfen)
24 60
  (Pindar GT)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 2+14
  COMMENTS: Registered for use in orchards established at least 9 months. Apply in 10 to 30 gal water/acre. Requires rainfall or irrigation within 14 days following treatment. Can be mixed with other preemergence herbicides for broader weed control. 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. Residual period: 5 to 8 months. Certain oxyfluorfen formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations of oxyfluorfen.
 
H. RIMSULFURON 0.031–0.063 lb a.i. 4 14
  (Matrix FNV)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 2
  COMMENTS: Registered for use in orchards established at least 1 year. Apply in 20 to 40 gal water/acre. Requires rainfall or irrigation within 21 days following treatment. Can be mixed with other preemergence herbicides for broader weed control. 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. Residual period: 5 to 8 months.
 
After weeds emerge
A. CARFENTRAZONE 0.03 lb a.i. 12 3
  (Shark EW)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: For use in bearing and nonbearing orchards. Selective on small, vigorously growing broadleaf weeds. Applications made under windy conditions, or when trees are in bloom can result in tree injury. Add a surfactant to the tank per label recommendations. A spray volume of 20 to 40 gallons water/acre is needed to thoroughly wet the weed foliage. Ensure the sprayer is thoroughly cleaned following treatment per label recommendations.
 
B. CLETHODIM 0.09–0.12 lb a.i. 24 365
  (Select Max)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: For use in nonbearing orchards only. 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. A crop oil concentrate (1% volume by volume) or nonionic surfactant (0.25% volume by volume) must be added. Use in 20 to 40 gallons water/acre.
 
C. DIQUAT 0.375–0.5 lb a.i. 24 365
  (Reglone)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 22
  COMMENTS: For use in nonbearing orchards only. Add a nonionic surfactant at 0.25% volume by volume. Apply in 20 to 60 gallons water/acre. Apply when weeds are less than 4 inches tall. Control is improved during warm, dry weather.
 
D. FLUAZIFOP-P-BUTYL 0.25–0.375 lb a.i. 12
  (Fusilade DX)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: For use in nonbearing orchards only. 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. A crop oil concentrate (1% volume by volume) or nonionic surfactant (0.25% volume by volume) must be added. Apply in 20 to 40 gallons water/acre; thorough coverage is important.
 
E. GLUFOSINATE 1–1.75 lb a.i. 12 14
  (Rely 280)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 10
  COMMENTS: For use in bearing and nonbearing orchards. Nonselective on small, vigorously growing annual broadleaf and grass weeds. Adding sprayable ammonium sulfate at 17 lb/100 gallons water may improve control. A spray volume of 20 to 40 gallons water/acre is needed to thoroughly wet the weed foliage. Ensure the sprayer is thoroughly cleaned following treatment per label recommendations.
 
F. GLYPHOSATE 0.4–3.3 lb a.e. 4 3
  (Roundup PowerMax, etc.) 0.4–3.3 qt 4 3
  WSSA MODE-OF-ACTION GROUP NUMBER1: 9
  COMMENTS: For use in bearing and nonbearing orchards. Apply to young, actively growing annual weeds or perennial weeds when flowering. Some perennials may require the higher label rate for control. 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 to 40 gallons water/acre. Adding sprayable ammonium sulfate at 17 lb/100 gallons water may improve control. Avoid drift onto green bark and foliage, or injury will result. To maximize control, do not cultivate weeds for 7 to 14 days after treatment. Can be mixed with low rates of oxyfluorfen or other postemergence herbicides for broader weed control. 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. If glyphosate-resistant weeds are present, consider other effective products.
  . . . or . . .
  (Touchdown) 1–3.75 lb a.e.; 0.8–3 qt 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 to 4 lb a.i. in 10 to 30 gallons water per 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 and foliage or injury will result.
 
G. OXYFLUORFEN 0.5–1 lb a.i. 24 See comments
  (Goal)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: For use in bearing and nonbearing orchards. Dormant application to young (4-leaf stage) weeds. May be combined with other postemergence herbicides for specific weeds. Can be applied in-season following bloom. Apply between May and 7 days before harvest. Certain oxyfluorfen formulations emit high amounts of volatile organic compounds (VOCs); use low-VOC formulations of oxyfluorfen.
 
H. PARAQUAT* 0.3–0.9 lb a.i. 12 7
  (Gramoxone) 1.2–3.6 pt 12 7
  WSSA MODE-OF-ACTION GROUP NUMBER1: 22
  COMMENTS: For use in bearing and nonbearing orchards. Apply in 20 to 60 gallons water per 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.
 
I. PYRAFLUFEN-ETHYL 0.000925–0.0053 lb a.i. 12 Prebloom
  (Venue)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: For use in bearing and nonbearing orchards before bloom. Selective on small, vigorously growing annual broadleaf weeds. Adding sprayable ammonium sulfate at 17 lb/100 gallons water may improve control A spray volume of 20 to 40 gallons water/acre is needed to thoroughly wet the weed foliage. Ensure the sprayer is thoroughly cleaned following treatment per label recommendations.
 
J. SAFLUFENACIL 0.04375 lb a.i. 12 7
  (Treevix)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 14
  COMMENTS: For use in bearing and nonbearing orchards. Apply in 20 to 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.
 
K. SETHOXYDIM 0.28–0.468 lb a.i. 12 15
  (Poast)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 1
  COMMENTS: For use in bearing and nonbearing orchards. 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. A crop oil concentrate must be added at 1% volume by volume. Use in 20 to 40 gallons water/acre with thorough spray coverage of the weed foliage.
 
L. 2,4-D AMINE* 1–1.4 lb a.e. 48 60
  (Orchard Master, etc.)
  WSSA MODE-OF-ACTION GROUP NUMBER1: 4
  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. Ensure the sprayer is thoroughly cleaned following treatment per label recommendations.
 
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.
* 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 safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the R.E.I. exceeds the P.H.I. The longer of two intervals is the minimum time that must elapse before harvest.
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
Acknowledgment for contributions to Weeds:
A. Shrestha, UC IPM Program, Kearney Agricultural Center, Parlier

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