Weed Control

NOTE:  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 (page 107) for information on the use of these herbicides.

glyphosate (Roundup Power Max): REI 12h, Group 9.

pelargonic acid (Scythe): PHI 1d, REI 12h, Group 17. Celery only. Use a 3 -10% solution (3 to 10 gallons per 100 gallons).

Herbicides Used Preemergence to Weeds

bensulide (Prefar 4E): REI 12h, Group 8.  Apply 5 to 6 qt/A.  Celery only.  Can be preplant incorporated by shallow cultivation (1-2”) or applied preemergence and incorporated by irrigation within 36 hours or application. Grass control only; should be supplemented with cultivation or another registered herbicide for broadleaf control. See label for rotation restrictions.

trifluralin (Treflan HFP)REI 12h, Group 3. Celery only.  Rate based on soil texture and crop, see label for details.  Apply 1 to 2 pt/A of Treflan HFP as a soil-incorporated treatment. Treflan HFP may be applied to direct seeded or transplant celery before planting, at planting, or immediately after planting. Little or no control of ragweed, mustard, and nutsedge.

Herbicides Used Pre- and Postemergence to Weeds

prometryn (Caparol 4L): PHI 30d for celery, PHI 60d for celeriac, REI 12h, Group 5. Primarily controls annual broadleaf weeds. Annual grasses may only be suppressed. Do not use on sand or loamy sand. Do not apply if crop is under water stress. Do not apply within 2 weeks after an application of an herbicidal oil, such as “carrot” oil.

For celery: Can be used pre- or postemergence. To avoid crop injury, make either 1 preemergence or 1 postemergence application (not both) per crop. For preemergence use, apply 2.4 to 3.2 pt/A at planting or shortly after planting but before the crop emerges. For postemergence use, 1.6 to 2 pt/A after the crop has 2 to 5 true leaves. May be applied over the top of the crop. Apply before weeds are 2" tall.

For celeriac: Do not exceed 4 pt/A per crop cycle. Make a single broadcast application at 1.6 to 4 pt/A in a minimum of 20 gal of water per acre after the crop has 6 to 8 leaves. Application may be made over the crop. Use the lower rate on coarse-textured soils and soils low in organic matter.  Apply before weeds are 2" tall.

Herbicides Used Postemergence to Weeds 

carfentrazone (Aim EC): REI 12h, Group 14.  Aim is a burndown herbicide and will injure any foliage it comes into contact with. Apply Aim to row middles of emerged crops with hooded sprayers to control emerged weeds, including crops grown on mulch or plastic.  Prevent any spray from contacting the crop, or injury will occur.  For best results, make application to actively growing weeds up to 4 inches tall and rosettes less than 3 inches across. Good coverage is essential for good control.  Apply up to 2 oz/A per application, and do not exceed a total of 6.1 oz/ per season. 

clethodim (Select Max)PHI 30d, 24hr REI, Group 1.  Will control grass weeds only. Apply to actively growing grasses.  See label for rate selection.  Multiple applications permitted of 9 to 16 oz/A per application, minimum 14-days between applications, not to exceed 64 oz/A per year.  Add 0.25% v:v nonionic surfactant (1 qt per 100 gal of spray).  Can also be used as a spot-spray by mixing 1/3-2/3% (0.44 to 0.85 oz per gallon) Select Max and 0.25% v:v nonionic surfactant (0.33 oz per gallon).  Spray to wet, but do not allow runoff of spray solution.

linuron (Lorox DF): PHI 45d celery, PHI 60d celeriac, REI 24h, Group 7. Apply as a single application of up to 3 lb/A after the celery or celeriac has been transplanted and establish, but before the crop is 8” tall.  For use in celery, only use on celery grown on muck soils. Do not apply when temperatures exceed 85 degrees F.  Do not apply as a tank mixture with surfactants, nitrogen or fertilizer solution, or other pesticides, as injury to the crop may result.

pelargonic acid (Scythe):  PHI 1d, REI 12h, Group 17. Celery only. Use a 3 -10% solution (3 to 10 gallons per 100 gallons). Use a 3 to 5% solution for annual weeds, a 5 to 7% solution for biennial and perennial weeds, and 7 to 10% solution for maximum burndown. Delivery rate for boom applications should be 75 to 200 gals of spray solution per acre; complete coverage of weed foliage is essential. Use a DIRECTED/ SHIELDED SPRAY; contact with crop will cause injury. For hand-held equipment, spray to completely wet all weed foliage but not to the point of runoff. Repeat applications as necessary. Tank mixes are allowed with this product. See label for complete details.

sethoxydim (Poast): PHI 30d, REI 12h, Group 1.  Celery only. Controls grass weeds only.  Apply to actively growing grasses (see product label for susceptible stage).  Maximum 1.5 pt/A per application, minimum 14-days between applications.  Do not exceed 3 pt/A per year. Use with crop oil concentrate (2.0 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 used as a spot-spray by mixing 1-1.5% (1.3 to 1.9 oz per gallon) Poast and 1% v:v crop oil concentrate (1.3 oz per gallon).  Spray to wet, but do not allow runoff of spray solution.