NOTES: For the herbicides listed below, one product trade name and formulation is provided for each active ingredient along with preharvest interval (PHI), restricted entry interval (REI), resistance management group number, and example of rates and special instructions. In many cases, there are other products available with the same active ingredient. However, not all products with the same active ingredient are registered for use in a crop. Always check the product label to be sure that the crop is listed before using.
Stale Seedbed
See Stale Seedbed Technique for information on the use of these herbicides or flaming.
- glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9.
- paraquat (Gramoxone SL 2.0*): restricted use. REI 12h or 24h, Group 22.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0.
Preemergent Herbicides (before weeds germinate)
- linuron (Lorox DF): PHI 14d, REI 24h, Group 5. Parsnips only. Apply 1.5-3 lbs/A per application, only 1 application allowed per year. Apply after planting but prior to crop emergence. Seed should be planted at least 1/2 inch deep. Lorox activity is higher on both weeds and parsnips if it has been cloudy for 3 or more days, so reduce the application rate if these conditions are met.
- pendimethalin (Prowl H2O): PHI 60d, REI 24h, Group 3. Carrots only. Apply up to 2.1 pt/A per application, only 1 application allowed per year. Can be applied to the soil surface within 2 days of seeding, before emergence of the crop or weeds, or at layby as a directed spray between the rows. Do not allow contact with the carrot plants or injury will occur. Do not apply over the top of emerged carrots.
- s-metolachlor (Dual Magnum): REI 24h, Group 15. MASSACHUSETTS, MAINE, and NEW HAMPSHIRE only. Carrots only. Make sure the label for your state is available for download before using this product. This is a restricted label available only 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. All label instructions will be supplied after the application for use is completed.
- trifluaralin (Treflan HFP): REI 12h, Group 3. Carrots only. Apply 1-2 pts/A per application. Apply and incorporate before planting. Incorporated 2-3” into the final seedbed within 24 hours of application. Disc twice after spraying for satisfactory incorporation. Rate based on soil texture, percent organic matter, and rainfall.
Pre- and Postemergent Herbicides
- prometryn (Caparol 4L): PHI 30d, REI 12h or 48h, Group 5. Carrots only. Apply 2-4 pts/A per application, up to 3 applications allowed per year. Do not exceed 8 pt/A per crop cycle or 16 pt/A per year. Apply in a minimum of 20 gal/A of spray. Do not exceed 1 application before carrots emerge (up to 4 pt/A) plus 1 (up to 4 pt/A) or 2 applications after carrots emerge. Can be applied before carrots have emerged, activate with water through rainfall or irrigation. Can also be applied over the top of carrot, until the 6-leaf stage. Include a nonionic surfactant (0.5% v:v, 2 qt per 100 gallons of spray) or crop oil concentrate (1% v:v, 1 gallon per 100 gallons of spray). Do not apply when temperatures exceed 85°F.
Postemergent Herbicides (after weeds germinate)
- carfentrazone (Aim EC): REI 12h, Group 14. Apply 0.5-2 oz/A per application, multiple applications allowed per year. Do not exceed 6.1 oz/A per season. Apply to row middles of emerged crops with hooded sprayers to control emerged weeds. Prevent any spray from contacting the crop, or injury will occur. For best results, make application to actively growing weeds up to 4” tall and rosettes less than 3” across.
- clethodim (Select Max): PHI 30d, REI 24h, Group 1. Apply 9-16 oz/A per application, up to 4 applications per year, a minimum of 14 days apart. Do not exceed 64 oz/A per year. Apply to actively growing grasses. Add 0.25% v:v nonionic surfactant (1 qt/100 gal of spray). Can also be applied as a spot-spray by mixing 0.33-0.66% (0.44-0.85 oz/gal) Select Max and 0.25% v:v nonionic surfactant (0.33 oz/gal). Spray to wet, but do not allow runoff of spray solution.
- fluazifop (Fusilade DX): PHI 45d, REI 12h, Group 1. Carrots only. Apply up to 24 oz/A per application, up to 2 applications allowed per year, a minimum of 14 days apart. Do not exceed 48 oz/A per year. Apply to actively growing grasses (see product label for susceptible stage). Add either crop oil concentrate (0.5-1%, 0.5-1 gallon per 100 gallons of spray) or nonionic surfactant (0.25-0.5%, 1-2 qt per 100 gal of spray).
- glyphosate (Roundup Power Max): PHI 14d, REI 4h, Group 9. Apply 10 oz to 3.1 qts/A per application, multiple applications allowed per year. Do not exceed 5 qts/A per year. Rate based on target weed species. Can be applied during fallow intervals, prior to planting or transplanting, at planting, or before crop has emerged. Could cause injury when applied prior to transplanting or direct-seeding into plastic mulch. Remove residual product from plastic mulch with a 0.5” of water through irrigation or rainfall prior to planting. Can also be applied with the wiper method using a 33% solution by volume. A maximum of 2 wiper applications allowed per year. The first application must be a minimum of 60 days before harvest and the second application must be a minimum of 7 days before harvest.
- linuron (Lorox DF): PHI 14d, REI 24h or 8d, Group 5. For carrots: Apply 1.5-3 lbs/A per application, multiple applications allowed per year. Do not exceed 4 lbs/A per year. Has not been tested on all varieties, crop tolerance should be verified before treating the entire field. Apply after carrots are at least 3” and before annual grasses exceed 2" tall and broadleaf weeds exceed 6" tall. Do not apply when the temperature exceeds 85° F as crop injury may result. Lorox activity is higher on both weeds and parsnips if it has been cloudy for 3 or more days, so reduce the application rate if these conditions are met. Do not apply Lorox as a tank mix with surfactant, nitrogen solution or other pesticides.
- metribuzin (Metribuzin 75): PHI 60d, REI 12h, Group 5. Carrots only. Apply 0.3 lb/A per application, up to 2 applications allowed per year, a minimum of 3 weeks apart. Do not exceed 0.6 lb/A per year. Apply as a broadcast spray when carrots have 5-6 true leaves and weeds are less than 1" tall and 1" in diameter. 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. Has not been tested on all varieties, crop tolerance should be verified before treating the entire field. Fair on grasses.
- paraquat (Gramoxone SL 3.0): restricted use. REI 12h or 24h (application type), Group 22. Carrots only. Apply 1.3-2.7 pts/A per application, up to 3 applications allowed per year, a minimum of 7 days apart. Do not exceed 8 pts/A per year. Apply before, during, or after planting, but before emergence as a banded or broadcast application. Apply in a minimum of 10 gal/A of spray. May be fatal if swallowed or inhaled. Applicators must complete an EPA-approved paraquat training listed on the following website https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training.... The training must be completed a minimum of every three years.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0. Apply a 3-10% solution (3-10 gallons per 100 gallons of spray). Rate based on target weed species. Apply in 75-200 gal/A of spray or with a spot sprayer until foliage is wet but not to the point of runoff. Repeat applications as necessary. Can apply for vegetative burndown during site preparation, prior to crop emergence from soil, as a directed and shielded spray during crop growth taking care to avoid contact with foliage and green tissue of crops, or as a harvest aid and desiccant to remove crop leaves or ease harvest.
- sethoxydim (Poast): PHI 30d for carrots,14d for parsnips, REI 12h, Group 1. Apply 2.5 pt/A per application, multiple applications allowed per year, a minimum of 14 days apart. Do not exceed 5 pt/A per year for carrots or 2.5 pt/A per year for parsnips. Apply to actively growing grasses. Use with crop oil concentrate (2 pt/A) or methylated seed oil (1.5 pt/A). Note that crop oil can cause injury under hot and humid conditions. Can also be applied as a spot-spray by mixing 1-1.5% (1.3-1.9 oz/gal) Poast and 1% v:v crop oil concentrate (1.3 oz/gal). Spray to wet, but do not allow runoff of spray solution.