Weed Control

Carrot & Parsnip - General Carrot & Parsnip Disease Control Carrot & Parsnip Insect Control

Stale Seedbed

The following herbicides are nonselective and are used to control weeds that are present in a field prior to planting or before the crop emerges, which is especially useful for the Stale Seedbed Technique (see the Weed Management section for more information).

Preemergent Herbicides (before weeds germinate)

HRAC Group 3:

  • pendimethalin (Prowl H2O): 2 pt/A; PHI 60d, REI 24h. Carrot only. 1 application per year. Can be applied to the soil surface within 2 days after seeding, before emergence of the crop or weeds, or at layby as a directed spray between the rows. Contact with crop will cause damage.
  • trifluaralin (Treflan HFP): 1 to 2 pt/A; REI 12h. Carrot only. 1 application per year. Apply and incorporate before planting; a second incorporation pass in the opposite direction may be required.

HRAC Group 15:

  • s-metolachlor (Dual Magnum): REI 24h. MA, ME, and NH only. Carrot only. Restricted label: Make sure the label for your state is available for download before using this product. Full label instructions are supplied to growers who apply through the website www.syngenta-us.com/labels/indemnified-label-login and agree to a waiver of liability. Main target weeds for this registration are galinsoga and yellow nutsedge. 

Pre- and Postemergent Herbicides

HRAC Group 5:

  • linuron (Lorox DF): 1.5 to 3 lb/A; PHI 14d, REI 24h. Do not exceed 4 lb/A per year. Do not apply when the temperature exceeds 85°F and use lower rate if applying after 3 or more cloudy days. Spray additives and tank-mixing not recommended. For carrots, apply after crop is at least 3” tall. For parsnips, 1 application per year, after planting but prior to crop emergence; seed should be planted at least ½” deep.
  • prometryn (Caparol 4L): 2 to 4 pt/A; PHI 30d, REI 48h. Carrot only. Do not exceed 8 pt/A per crop cycle or 16 pt/A per year. Apply before or after crop emergence, until the 6-leaf stage. Do not exceed 1 application before carrots emerge (up to 4 pt/A) plus 1 (up to 4 pt/A) or 2 applications (up to 2 pt/A) after carrots emerge. Do not apply when the temperature exceeds 85°F and use lower rate if applying after 3 or more cloudy days.

Postemergent Herbicides (after weeds germinate)

HRAC Group 0:

  • pelargonic acid (Scythe): 3% to 10% solution; PHI 1d, REI 12h. Apply for vegetative burndown during site preparation, prior to crop emergence from soil, as a directed and shielded spray, or as a harvest aid. Contact with crop will cause damage. 

HRAC Group 1:

  • clethodim (Select Max): 9 to 16 fl oz/A; PHI 30d, REI 24h. Do not exceed 64 fl oz/A per year. Apply to actively growing grasses.
  • fluazifop (Fusilade DX): 6 to 24 fl oz/A; PHI 45d, REI 12h. Carrot only. Do not exceed 48 fl oz/A per year. Apply to actively growing grasses.
  • sethoxydim (Poast): 2.5 pt/A; PHI 30d carrots, 14d parsnips, REI 12h. Do not exceed 5 pt/A per year (carrots) or 2.5 pt/A per year (parsnips). Apply to actively growing grasses. BASF has stopped production and will discontinue the registration at the end of 2027.

HRAC Group 5:

  • metribuzin (Metribuzin 75): 0.3 lb/A; PHI 60d, REI 12h. Carrot only. Do not exceed 0.6 lb/A per year. Apply as a broadcast spray when crop has 5–6 true leaves. Do not apply within 3 days of cool or wet weather or within 3 days of other sprays. Yellowing and burning of leaf tissue may occur.

HRAC Group 9:

  • glyphosate (Roundup Power Max): 10 fl oz to 3.1 qt/A; PHI 7d for carrot wiper applicator or 14d for all other uses, REI 4h. Do not exceed 5 qt/A per year. Apply during fallow intervals, prior to planting, at planting, before crop has emerged, or to row middles with a hooded or shielded sprayer or wiper applicator. For carrot, can also be applied over the top of the crop with a wiper applicator. Spray contact will cause crop death. Spray additive recommendation varies with formulation–see label.

HRAC Group 14:

  • carfentrazone (Aim EC): 0.5 to 2 fl oz/A; PHI 0d, REI 12h. Do not exceed 6.1 fl oz/A per year. Apply as a pre-plant burn-down up to 7 days before seeding, or to row middles of emerged crop with hooded sprayer. Contact with crop will cause damage.

HRAC Group 22:

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New England Vegetable Management Guide