Asparagus

Pest Management Guidelines


Herbicide Treatment Table

(Reviewed 6/09, updated 2/12)

In this Guideline: More about weeds in asparagus:

Herbicide Amount per Acre R.E.I.‡ P.H.I.‡
(example 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
A. METAM SODIUM* 50–75 gal see label NA
  (Vapam)
  COMMENTS: Fumigants such as metam sodium are a source of volatile organic compounds (VOCs) but are minimally reactive with other air contaminants that form ozone. Fumigate only as a last resort when other management strategies have not been successful or are not available.
 
STAND ESTABLISHMENT
A. GLYPHOSATE 0.25–0.453 lb a.i. 4 NA
  (Roundup) 0.34–3.3 qt  
  . . . or . . .
  (Touchdown Total) 0.375–3.75 lb a.i. 12 NA
    0.35–3.6 qt  
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: A nonselective foliar herbicide used to control small annual weeds in finished beds before the asparagus emerges. Asparagus emerged at the time of treatment will be killed.
 
B. PARAQUAT* 0.65–1 lb a.i. 24 see label
  (Gramoxone Inteon) 2.6-4 pt  
  WSSA MODE OF ACTION GROUP NUMBER1: 22
  COMMENTS: A nonselective foliar herbicide without soil activity applied as a band or broadcast treatment before or after planting, but before the asparagus emerges. Asparagus that has emerged at the time of application will be killed. Apply when weeds are succulent and less than 16 inches high; larger weeds are less affected. Surfactant is needed. Late afternoon applications increase activity.
 
C. PELARGONIC ACID 2.25–14 gal/broadcast acre 12 0
  (Scythe) 3%–7% spray solution  
  MODE OF ACTION: Unknown.
  COMMENTS: A contact, nonselective foliar herbicide without residual activity. The degree of control is greater when weeds are actively growing, small, and immature; larger weeds are less affected. Apply as a band treatment over the crop row or as a broadcast treatment at or before planting. Provides control of annuals and some suppression of perennials. For best results, target weeds should be thoroughly wetted with spray solution but not to the point of runoff. Use 75-200 gal spray solution/broadcast acre, with higher volume used when weed density is high. A 3-5% solution is sufficient for most annual weeds while perennial or large annual weeds require a 7% solution.
 
D. LINURON 0.5–1 lb a.i. 24 1
  (Lorox) 1–2 lb  
  WSSA MODE OF ACTION GROUP NUMBER1: 7
  COMMENTS: Can be applied over the top to direct-seeded, transplanted, or crown plantings when ferns have 6–18 inches of growth. Has excellent activity on small emerged annual weeds. Do not apply with an adjuvant or in a fertilizer mix.
 
E. SETHOXYDIM 0.281–0.468 lb a.i. 12 1
  (Poast) 1.5–2.5 pt  
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: For use on direct-seeded or transplanted plantings. Apply to actively growing grasses that are not under moisture stress; best applied 2–4 days after a rain or irrigation. Apply in 10–20 gal water plus an oil concentrate at the rate of 1 qt/acre. Rates dependent on grass size and species. Follow label instructions regarding the use of adjuvants.
 
F. DIURON 0.8–1.6 lb a.i. 12 0
  (Karmex, etc.) 1–2 lb  
  WSSA MODE OF ACTION GROUP NUMBER1: 7
  COMMENTS: For use on crown-planted plants in the San Joaquin Delta only. Considered to be a groundwater contaminant and requires a use permit within Groundwater Protection Areas. Soils should have greater than 2% organic matter; crowns must be buried at least 2 inches deep. Use lower rates on coarse-textured soils.
 
G. FLUAZIFOP-P-BUTYL 0.1875 lb a.i. 12 1
  (Fusilade DX) 12 oz  
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: For use on asparagus that is either direct-seeded, transplanted, or crown planted. Apply in 20–40 gal water/acre along with a 1% crop oil concentrate. Rates depend on grass size and species. Follow label instructions regarding the use of adjuvants.
 
ESTABLISHED CUTTING BEDS
Preemergence (When spears are not present)
A. GLYPHOSATE 0.25–0.453 lb a.i. 4 NA
  (Roundup) 0.25–5 qt  
  . . . or . . .
  (Touchdown Total) 0.375–3.75 lb a.i. 12 NA
    0.35–3.6 qt  
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: A nonselective foliar herbicide used to control small annual weeds in finished beds before spears emerge. Asparagus spears emerged at the time of treatment will be damaged and should be discarded. Use the higher rate to control perennial weeds.
 
B. PARAQUAT* 0.65–1 lb a.i. 24 see label
  (Gramoxone Inteon) 2.6–4 pt  
  WSSA MODE OF ACTION GROUP NUMBER1: 22
  COMMENTS: A nonselective foliar herbicide without soil activity applied as a band or broadcast treatment before spears emerge. Asparagus that has emerged at the time of application will be damaged. Apply when weeds are succulent and 16 inches high; larger weeds are less affected. Surfactant is needed. Late afternoon applications increase activity.
 
C. PELARGONIC ACID 2.25–14 gal/broadcast acre 12 0
  (Scythe) 3%–7% spray solution  
  MODE OF ACTION: Unknown.
  COMMENTS: A contact, nonselective foliar herbicide without residual activity. The degree of control is greater when weeds are actively growing, small, and immature; larger weeds are less affected. Apply as a band treatment over the crop row or as a broadcast treatment at or before planting. Provides control of annuals and some suppression of perennials. For best results, target weeds should be thoroughly wetted with spray solution but not to the point of runoff. Use 75-200 gal spray solution/broadcast acre, with higher volume used when weed density is high. A 3-5% solution is sufficient for most annual weeds while perennial or large annual weeds require a 7% solution.
 
D. METRIBUZIN 0.9975–1.995 lb a.i. 12 14
  (Metribuzin 75) 1.33–2.66 lb  
  WSSA MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: Apply to soil; metribuzin has both soil and foliar activity on newly emerged annual weeds. Soil should not be moved after application. Rainfall or irrigation necessary for activation of this herbicide.
 
E. DIURON 0.8–3.2 lb a.i. 12 0
  (Karmex, etc.) 1–4 lb  
  WSSA MODE OF ACTION GROUP NUMBER1: 7
  COMMENTS: Apply as a band or broadcast treatment to weedfree beds no earlier than 4 weeks before spears emerge; a second application may be made following harvest. Incorporate mechanically or with irrigation if rainfall does not occur. Considered to be a groundwater contaminant and requires a use permit within Groundwater Protection Areas. Do not use on soils with less than 2% organic matter; use lower rates on coarse-textured soils.
 
F. NAPROPAMIDE 4 lb a.i. 24 0
  (Devrinol) 50 DF 8 lb    
  WSSA MODE OF ACTION GROUP NUMBER1: 15
  COMMENTS: Apply to weed-free soil in established beds. Requires shallow (1–2 inch) mechanical incorporation, and if rain fall does not occur, it must be irrigated.
 
G. Pendimethalin 1.1–3.8 lb a.i. 24 14
  (Prowl H2O) 2.4–8.2 pt  
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: With a single application apply up to 8.2 pints/acre to the soil surface at least 14 days before harvest. On sandy soils, do not apply more than 2.4 pints/acre. Application must be made prior to spear emergence and prior to weed emergence. This material will not control emerged weeds.
 
H. TRIFLURALIN 0.5–2 lb a.i. 12 0
  (Treflan, and others)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Apply to established asparagus after bed preparation but before spears emerge. Trifluralin has no postemergence activity on weeds and must be mechanically incorporated immediately after application with disks or rolling cultivators in two directions or with a power driven incorporator in one direction. Higher rates necessary for the suppression of field bindweed.
 
I. LINURON 0.5–1 lb a.i. 24 1
  (Lorox) 1–2 lb  
  WSSA MODE OF ACTION GROUP NUMBER1: 7
  COMMENTS: A soil-applied herbicide noted for its foliar activity on small seedling, broadleaf weeds and for its relatively short soil residual activity. Can be applied immediately after cutting, but do not harvest within one day after application. Do not apply more than 4 lb a.i./acre/season with a maximum of 3 applications/year.
 
J. FLUAZIFOP-P-BUTYL 0.1875 lb a.i. 12 1
  (Fusilade) DX 12 oz  
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Do not apply more than 24 fl oz/acre/season. Do not make sequential applications at less than a 3-week interval.
 
K. SETHOXYDIM 0.281–0.468 lb a.i. 12 1
  (Poast) 1.5–2.5 pt  
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Apply to actively growing grasses that are not under moisture stress; best applied 1-2 days after a rain or irrigation. Rate depends on grass size and species. Follow label instructions regarding the use of adjuvants.
 
L. FLUMIOXAZIN 0.19 lb a.i. 12 14
  (Chateau) 6 oz  
  WSSA MODE OF ACTION GROUP NUMBER1: 14
  COMMENTS: Apply no less than 14 days before spears emerge and before weeds emerge, or burn weeds back with a tank-mix material. Requires 0.25 inch of rainfall or irrigation to activate the material.
 
M. HALOSULFURON 0.023–0.046 lb a.i. 12 1
  (Sandea) 0.5–1 oz  
  WSSA MODE OF ACTION GROUP NUMBER1: 2
  COMMENTS: May be applied before harvest season. Works best on nutsedge when it is actively growing (i.e. following an irrigation). Do not use adjuvant with any applications made before or during harvest. Check label for regional constraints.
 
ESTABLISHED CUTTING BEDS
Postemergence (After spears emerge)
A. DICAMBA* 0.25–0.5 lb a.i. 24 1
  (Banvel) 0.5–1 pt  
  WSSA MODE OF ACTION GROUP NUMBER1: 4
  COMMENTS: Apply immediately after cutting but at least 24 hours before the next harvest. Postharvest applications should be done as directed sprays to avoid fern contact. Do not use in Coachella Valley. Do not exceed 1 pt/acre/season.
 
B. LINURON 0.5–1 lb a.i. 24 1
  (Lorox) 1–2 lb  
  COMMENTS: A soil-applied herbicide noted for its foliar activity on small seedling, broadleaf weeds and for its relatively short soil residual activity. Can be applied immediately after cutting, but do not harvest within one day after application. Do not apply more than 4 lb a.i./acre/season with a maximum of 3 applications/year.
 
C. HALOSULFURON 0.0234–0.0703 lb a.i. 12 1
  (Sandea) 0.5–1.5 oz  
  WSSA MODE OF ACTION GROUP NUMBER1: 2
  COMMENTS: May be applied before or during harvest season. Works best on nutsedge when it is actively growing (i.e. following an irrigation). Do not use adjuvant with any applications made before or during harvest. Check label for regional constraints.
 
D. FLUAZIFOP-P-BUTYL 0.1875 lb a.i. 12 1
  (Fusilade) DX 12 oz  
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Do not apply more than 24 fl oz/acre/season. Do not make sequential applications at less than a 3-week interval.
 
E. SETHOXYDIM 0.281–0.468 lb a.i. 12 1
  (Poast) 1.5–2.5 pt  
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Apply to actively growing grasses that are not under moisture stress; best applied 1-2 days after a rain or irrigation. Rate depends on grass size and species. Follow label instructions regarding the use of adjuvants.
 
ESTABLISHED CUTTING BEDS
Postharvest and fern stage
A. GLYPHOSATE 0.25–0.453 lb a.i. 4 see label
  (Roundup) 0.34–3.3 qt    
  . . . or . . .
  (Touchdown Total) 0.375–3.75 lb a.i. 12 see label
    0.35–3.6 qt    
  WSSA MODE OF ACTION GROUP NUMBER1: 9
  COMMENTS: A nonselective foliar herbicide used to control both annual and perennial weeds. Use on clean cut beds after all remaining spears have been removed. Higher rates of application are necessary for the control of perennial weeds. Direct contact of the spray to asparagus can cause serious injury. Useful as a spot treatment for the control of perennial weeds at field edges. Do not apply within a week before the first asparagus spears emerge.
 
B. HALOSULFURON 0.0234–0.0703 lb a.i. 12 1
  (Sandea) 0.5-1.5 oz    
  WSSA MODE OF ACTION GROUP NUMBER1: 2
  COMMENTS: May be applied at end of harvest season. Under heavy nutsedge pressure split applications are recommended. Works best on nutsedge when it is actively growing (i.e. following an irrigation). Use drop nozzles to improve coverage on weeds and reduce contact with fern.
 
C. DIURON 0.8–3.2 lb a.i. 12 0
  (Karmex, etc.) 1–4 lb    
  WSSA MODE OF ACTION GROUP NUMBER1: 7
  COMMENTS: Can be applied following the harvest period. Do not exceed seasonal application limits.
 
D. TRIFLURALIN 0.5–2 lb a.i. 12 0
  (Treflan, and others)
  WSSA MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: Can be mechanically incorporated to suppress bermudagrass and other grasses following the harvest period but before fern growth.
 
E. LINURON 0.5–1 lb a.i. 24 1
  (Lorox) 1–2 lb    
  WSSA MODE OF ACTION GROUP NUMBER1: 7
  COMMENTS: Can be used as a directed spray to the base of the fern.
 
F. FLUAZIFOP-P-BUTYL 0.1875 lb a.i. 12 1
  (Fusilade) DX 12 oz    
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Can be used before the fern stage to suppress bermudagrass and other grasses.
 
G. SETHOXYDIM 0.281–0.468 lb a.i. 12 1
  (Poast) 1.5–2.5 pt    
  WSSA MODE OF ACTION GROUP NUMBER1: 1
  COMMENTS: Apply to actively growing grasses that are not under moisture stress; best applied 1-2 days after a rain or irrigation. Rate depends on grass size and species. Follow label instructions regarding the use of adjuvants.
 
H. METRIBUZIN 0.9975–1.995 lb a.i. 12 14
  (Metribuzin 75) 1.33–2.66 lb    
  WSSA MODE OF ACTION GROUP NUMBER1: 5
  COMMENTS: Apply after last harvest of the season but before fern growth begins.
 
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.
NA Not applicable.
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: Asparagus
UC ANR Publication 3435

Weeds
  • R. F. Smith, UC Cooperative Extension, Monterey County
Acknowledgment for contributions to Weeds:
  • D. W. Cudney, Botany and Plant Sciences, UC Riverside
  • C. E. Bell, UC Cooperative Extension, Imperial County
  • R. J. Mullen, UC Cooperative Extension, San Joaquin County

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