Before establishing an asparagus planting, reduce perennial weeds in the area to be planted with systemic broad-spectrum herbicides. Herbicide options are limited in the planting year.
After the first year of establishment, a typical weed control program in asparagus includes a preemergence herbicide with a long residual applied before asparagus emerges. If needed, a preemergence herbicide may be applied again after harvest is finished and a clean mowing.
Postemergence herbicides may be applied before asparagus emergence or during or after the harvest season. Some require directed or shielded spray applications to avoid spraying asparagus.
It is important use herbicides with different modes of action from year to year with this perennial crop to avoid buildup of weed species not controlled by a particular mode of action.
For specific weeds controlled by each herbicide, check the Relative Effectiveness of Herbicides for Vegetable Crops table.
Rates provided in the recommendations below are given for overall coverage. For a banded treatment, reduce amounts according to the portion of acre treated.
Non-Pesticide Options
Good weed control in the planting year is especially important. Multivators, tines, rolling cultivators, and flame weeders work well before emergence of asparagus, but it is important to avoid damaging crowns when cultivating. Cultivate row-middles and hand-hoe after emergence. Flame weeders can also be used after clean harvest or mowing. Once established, straw mulch can be applied any time, but is easier for picking when applied after final harvest.
2,4-D
2,4-D
HRAC 04
Available as both amine and choline formulations. Use 3-4 pts. per acre of liquid formulations with 3.8 lbs. per gal. acid equivalent. Apply before, during, or after the harvest season. During harvest season apply immediately after cutting. Discard deformed spears. Use drop nozzles for treatments after harvest to avoid spraying fern. Wait at least 30 days between applications.
Postemergence
During asparagus harvest after cutting; After final asparagus harvest, before new growth; After final asparagus harvest and new growth; When crop is dormant
Between rows, crop protected from spray; Broadcast, over top of weeds
48-hour
3-day.
warning
No
No
No
Intermediate Risk
Low Risk
Do not apply or allow to drift to plants that are flowering, or water puddles, except when the application is made between sunset and midnight if allowed by the pesticide label and regulations.
Toxic to honey bee brood.
Aim EC
carfentrazone
HRAC 14
Include 0.5 pt. NIS or 0.25-0.5 gals. COC per 25 gals. of spray solution. Broadcast after spear harvest. Emerged asparagus will be injured. Do not exceed 3.8 fl. oz. per acre per season. Wait at least 20 days between applications.
Postemergence
During asparagus harvest after cutting; After final asparagus harvest, before new growth; When crop is dormant
Broadcast, over top of weeds
12-hour
5-day.
caution
No
Silent
No
Low Risk
Low Risk
No bee precaution, except when required by the pesticide label or regulations.
Callisto
mesotrione
HRAC 27
Apply in spring before spears emerge after mowing, disking, or tilling; after final harvest; or both. For postharvest applications use drop nozzles or other equipment that will minimize contact with crop. Adding COC or NIS (alone or with UAN or AMS) will improve emerged weed control and increase crop injury risk in postharvest applications. Do not exceed 2 applications per year, or 7.7 fl. oz. per acre per year.
Preemergence; Postemergence
After final asparagus harvest, before new growth; When crop is dormant
Between rows, crop protected from spray; Broadcast, surface application
12-hour
caution
Certain systems or crops, see label
Silent
No
High Risk
Low Risk
Chateau SW
flumioxazin
HRAC 14
Established plantings only. Apply to dormant asparagus at least 2 weeks before spears emerge. Crop injury may result if asparagus is not dormant. May be tank-mixed with paraquat to control emerged weeds. Or, apply after final harvest for the season before fern emerges. Do not exceed 6 oz. per acre per growing season.
Preemergence
After final asparagus harvest, before new growth; When crop is dormant
Broadcast, surface application
12-hour.
caution
Certain systems or crops, see label
Silent
Yes, see label
Low Risk
Intermediate Risk
No bee precaution, except when required by the pesticide label or regulations.
Clarity
dicamba
HRAC 04
Apply in 40-60 gals. of water per acre immediately after cutting. Discard crooked spears at harvest. Clarity can injure nearby broadleaf crops and garden plants. Maximum 1 pt. per acre per year.
Postemergence
During asparagus harvest after cutting
Broadcast, over top of weeds
24-hour
1-day.
caution
No
Silent
No
High Risk
Low Risk
No bee precaution, except when required by the pesticide label or regulations.
clethodim products
clethodim
HRAC 01
Use 2EC formulations at 6-8 fl. oz. per acre with 1 qt. of COC per 25 gals. of spray solution (1% v/v). Use Select Max at 9-16 fl. oz. per acre with 8 fl. oz. of NIS per 25 gals. of spray solution (0.25% v/v).
Spray on actively growing grass. Wait at least 14 days between applications.
Do not exceed 32 fl. oz. of 2EC formulations or 64 fl. oz. of Select Max per acre per season.
Postemergence
After crop seeding before emergence; During asparagus harvest after cutting; After final asparagus harvest, before new growth; After final asparagus harvest and new growth; When crop is dormant
Broadcast, over top of crop and weeds; Broadcast, over top of weeds
24-hour
1-day.
warning
Certain systems or crops, see label
Certain crops, see label
No
Low Risk
Low Risk
No bee precaution, except when required by the pesticide label or regulations.
clopyralid products
clopyralid
HRAC 04
Apply Spur before or during harvest. May cause some crooking of spears. Controls Canada thistle, marestail, mayweed, nightshade, plantain, smartweeds. Do not exceed 10.7 fl. oz. per acre per year. Avoid application 2 years in succession.
Postemergence
After crop seeding before emergence; During asparagus harvest after cutting; After final asparagus harvest, before new growth; When crop is dormant
Broadcast, over top of weeds
12-hour.
2-day.
caution
No
No
No
High Risk
Low Risk
diuron products
diuron
HRAC 05
Established plantings only. Do not apply to young plants during the first year. Use 80DF formulations at 1-4 lbs. per acre, and do not exceed 6 lbs. per acre per season. Use 4L formulations at 0.8-3.2 qts. per acre and do not exceed 4.8 qts. per acre per season. Use lower rates on light-colored soils with less than 2% organic matter. Apply after tillage or chopping fern in the spring and again after harvest, if necessary. See product label for split application rates. 6-8 weeks of residual activity. RUP in Michigan only.
Preemergence
After final asparagus harvest, before new growth; When crop is dormant
Broadcast, surface application
12-hour
caution
yes
No
Silent
Yes, see label
Intermediate Risk
Intermediate Risk
No bee precaution, except when required by the pesticide label or regulations.
Dual Magnum
s-metolachlor
HRAC 15
Illinois, Indiana, Michigan, and Minnesota 24c label only. Apply before asparagus and weeds emerge in spring or after the harvest season. Needs moisture for activation. Do not exceed 1 application per crop.
Preemergence
After final asparagus harvest, before new growth; When crop is dormant
Broadcast, surface application
24-hour
16-day.
caution
Certain systems or crops, see label
Silent
No
High Risk
Intermediate Risk
No bee precaution, except when required by the pesticide label or regulations.
Fusilade DX
fluazifop-P
HRAC 01
Include 1-2 pts. of COC or 0.5-1 pt. of NIS per 25 gals. of spray solution. Spray on actively growing grass. Rates may be doubled if asparagus will not be harvested for 12 months. Wait at least 14 days between applications. Do not exceed 48 fl. oz. per acre per season on bearing asparagus.
Postemergence
After crop seeding before emergence; After crop emergence or transplanting; During asparagus harvest after cutting; After final asparagus harvest, before new growth; After final asparagus harvest and new growth; When crop is dormant
Broadcast, over top of crop and weeds; Broadcast, over top of weeds
12-hour
1-day.
caution
Certain systems or crops, see label
Silent
Yes, see label
Low Risk
Intermediate Risk
No bee precaution, except when required by the pesticide label or regulations.
glyphosate products
glyphosate
HRAC 9
Use formulations containing 3 lbs. ae per gal. (4 lbs. isopropylamine salt per gal.) at 1-5 qts. per acre, or formulations containing 4.5 lbs. ae per gal. (5 lbs. potassium salt per gal) at 0.66-3.3 qts. per acre. Apply to emerged weeds at least 7 days before spears emerge or immediately after last harvest. Use low rate for annuals and higher rates for perennials.
See label for suggested application volume and adjuvants. If spears are allowed to regrow, delay application until ferns have developed and apply as a directed or shielded spray. Contact of the spray with asparagus fern may result in crop injury.
Postemergence
Before crop seeding; Before crop transplanting; After crop seeding before emergence; After final asparagus harvest, before new growth; When crop is dormant
Between rows, crop protected from spray; Broadcast, over top of weeds
4-hour to 12-hour
14-day.
caution
No
Yes
No
Low Risk
High Risk
Do not apply or allow to drift to plants that are flowering, or water puddles, except when the application is made between sunset and midnight if allowed by the pesticide label and regulations.
Toxic to honey bee brood.
Lorox DF
linuron
HRAC 05
Established crowns: Apply before spears emerge, before cutting season or immediately after cutting, or as directed spray in ferns.
New planted crowns: To control small emerged weeds apply 1-2 lbs. per acre, up to 2 applications when ferns are 6-18 inches tall.
Newly seeded crops: Apply a 1-inch band of activated charcoal over the row at planting, then apply Lorox. Use charcoal at 300 lbs. per acre of actual area sprayed, which is equivalent to 15 lbs. per acre of crop with a 20-inch row-spacing. Or, use the low rate of Lorox when ferns are 6-18 inches tall and weeds are less than 4 inches tall.
Do not use on sand, loamy sand, or soils with less than 1% organic matter. Maximum 4 lbs. or 3 applications per acre per year.
Preemergence; Postemergence
After crop seeding before emergence; After final asparagus harvest, before new growth; After final asparagus harvest and new growth; When crop is dormant
Broadcast, surface application; Broadcast, over top of crop and weeds; Broadcast, over top of weeds
24-hour to 8-day.
1-day.
caution
Certain systems or crops, see label
Silent
No
Intermediate Risk
Intermediate Risk
No bee precaution, except when required by the pesticide label or regulations.
metribuzin products
metribuzin
HRAC 05
Established plantings only. Do not apply to young plants during first year. Use 75DF formulations at 0.6-2.6 lbs. per acre. Use 4F formulations at 2-4 pts. per acre. See product label for split application rates. Use low rate if combined with diuron. 6-8 weeks residual activity. Two sprays necessary for seasonlong sandbur control. Do not exceed 2.6 lbs. or 4 pts. per acre per year.
Preemergence; Postemergence
After final asparagus harvest, before new growth; When crop is dormant
Broadcast, surface application; Broadcast, over top of weeds
12-hour
14-day.
caution
Certain systems or crops, see label
Silent
No
High Risk
Low Risk
No bee precaution, except when required by the pesticide label or regulations.
paraquat products
paraquat
HRAC 22
Include 1 qt. of COC, or 4-8 fl. oz. of NIS per 25 gallons of spray solution. Apply before crop emergence or after last harvest before fern regrows.
Postemergence
Before crop seeding; Before crop transplanting; After crop seeding before emergence; After final asparagus harvest, before new growth; When crop is dormant
Broadcast, over top of weeds
12 to 24-hour.
6-day.
danger
yes
No
Silent
Yes, see label
Very Low Risk
High Risk
Do not apply or allow to drift to plants that are flowering, or water puddles, except when the application is made between sunset and midnight if allowed by the pesticide label and regulations.
Toxic to honey bee brood.
pendimethalin products
pendimethalin
HRAC 03
Use formulations with 3.8 lbs. active ingredient per gallon. Apply at least 14 days before first harvest and prior to spear emergence. If spears are present, remove before application. On sandy soil use no more than 2.4 pts. per acre. Do not apply to newly seeded asparagus during first year.
Preemergence
When crop is dormant
Broadcast, surface application
24-hour.
14-day.
caution
Certain systems or crops, see label
Silent
No
Low Risk
High Risk
No bee precaution, except when required by the pesticide label or regulations.
Poast
sethoxydim
HRAC 01
Include 1 qt. COC per acre. Spray on actively growing grass. Use high rate on quackgrass. Do not exceed 5 pts. per acre per season.
Postemergence
After crop seeding before emergence; After crop emergence or transplanting; During asparagus harvest after cutting; After final asparagus harvest, before new growth; After final asparagus harvest and new growth; When crop is dormant
Broadcast, over top of crop and weeds; Broadcast, over top of weeds
12-hour
1-day.
warning
No
Silent
No
Low Risk
Low Risk
Do not apply or allow to drift to plants that are flowering, or water puddles, except when the application is made between sunset and midnight if allowed by the pesticide label and regulations.
QuinStar 4L
quinclorac
HRAC 04
Include 1 qt. of COC per 25 gallons of spray solution. Apply after final harvest for the year. Controls bindweed, Canada thistle, barnyardgrass, large crabgrass. Do not exceed 1 application per year.
Postemergence
After final asparagus harvest and new growth
Broadcast, over top of crop and weeds
12-hour
caution
No
Silent
No
High Risk
Intermediate Risk
No bee precaution, except when required by the pesticide label or regulations.
Sandea
halosulfuron
HRAC 02
Apply before, during, or after harvest. Drop nozzles and using COC or NIS are recommended for applications after harvest. For first year transplants do not apply sooner than 6 weeks after fern emergence. Do not exceed 2 applications per crop cycle, or 2 oz. per acre per 12-month period. Has residual soil activity. Effective on nutsedge.
Preemergence; Postemergence
After crop seeding before emergence; During asparagus harvest after cutting; After final asparagus harvest, before new growth; After final asparagus harvest and new growth; When crop is dormant
Between rows, crop protected from spray; Broadcast, over top of weeds
12-hour
1-day.
caution
No
Silent
No
Intermediate Risk
Low Risk
No bee precaution, except when required by the pesticide label or regulations.
Sinbar WDG
terbacil
HRAC 05
Established crowns or direct-seeded crops only. Do not use on sandy soil or on soil with less than 1% organic matter. Established crowns: Apply in spring after cutting fern and prior to spear emergence. May also be applied after a clean cutting. Seeded crops: At planting spray activated charcoal at 300 lbs.per acre of actual area treated in a 1-inch band over the row (equivalent to 15 lbs. per acre of crop with 20-inch row spacing), then apply Sinbar. Do not plant other crops within 2 years of application. 8-12 weeks residual activity.
Preemergence; Postemergence
After final asparagus harvest, before new growth; When crop is dormant
Broadcast, surface application
12-hour
5-day.
caution
No
Silent
No
High Risk
Intermediate Risk
Solicam DF
norflurazon
HRAC 12
Established plantings only. Do not apply within 12 months of planting. Apply preemergence to soil free of weeds and debris.
Preemergence
When crop is dormant
Broadcast, surface application
12-hour
14-day.
caution
No
No
No
Intermediate Risk
Intermediate Risk
No bee precaution, except when required by the pesticide label or regulations.
Spartan 4F
sulfentrazone
HRAC 14
Michigan only - applicators must have a supplemental label. Established plantings only. Apply in spring before crop emerges. Use low rate on light soil. Do not use on soils with less than 1% organic matter. Do not exceed 1 application and 12 fl. oz. per acre per season.
Preemergence
When crop is dormant
Broadcast, surface application
12-hour
14-day.
caution
Certain systems or crops, see label
Silent
No
High Risk
Intermediate Risk
No bee precaution, except when required by the pesticide label or regulations.
trifluralin products
trifluralin
HRAC 03
Established plantings only. Use 4EC formulations at 2-4 pts. per acre. Use 10G formulations at 10-20 lbs. per acre. Use lower rates on coarse soils. Apply and incorporate 1-2 inches early in the spring when spears are at least 4 inches below soil surface. See product label for split application instructions. 4-6 weeks of residual activity.
Preemergence
When crop is dormant
Broadcast, incorporate
12-hour
caution
Certain systems or crops, see label
Silent
No
Low Risk
High Risk
No bee precaution, except when required by the pesticide label or regulations.
Tripzin ZC
pendimethalin
HRAC 03
metribuzin
HRAC 05
Broadcast 14 days before emergence. Do not apply to seedlings or first-year transplants.
Preemergence; Postemergence
After crop seeding before emergence
Broadcast, surface application; Broadcast, over top of weeds
24-hour.
14-day.
caution
Certain systems or crops, see label
Silent
No
Low Risk
High Risk
No bee precaution, except when required by the pesticide label or regulations.
No bee precaution, except when required by the pesticide label or regulations.
The Midwest Vegetable Production Guide for Commercial Growers is a collaboration of land-grant universities from eight states. It provides vegetable production information that is valid in the participating states for the current year. This includes fertility, variety, cultural, and pest management recommendations. The online guide was supported by MSU Extension, and donations from the Michigan Vegetable Council, the Indiana Vegetable Growers Association, the Kansas Vegetable Growers Association, and by the Crop Protection and Pest Management Program [grant no 2021-70006-35450] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.
The management practices, products, and cultivars discussed in this publication are the research and experience-based recommendations of the institutions associated with the contributing editors and authors. These recommendations are not exhaustive and other practices and products not mentioned in this guide might also be effective. Read and follow label instructions before using any pesticide product.
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