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.
- carfentrazone (Aim EC): REI 12h, Group 14.
- glyphosate (Roundup Power Max): PHI 7d, REI 4h, Group 9.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0.
Preemergent Herbicides (before weeds germinate)
- bensulide (Prefar 4E): REI 12h, Group 0. Celery only. Apply 5-6 qt/A per application. Do not exceed 6 quarts per year. Can be applied before planting or after planting before crop has emerged. Incorporate 1-2” into the soil within 36 hours by shallow cultivation or with water through irrigation or rainfall. Grass control only; should be supplemented with cultivation or another registered herbicide for broadleaf control.
- trifluralin (Treflan HFP): REI 12h, Group 3. Celery only. Apply 1-2 pts/A per application, only 1 application allowed per year. Can be applied to direct seeded or transplanted celery before planting, at planting, or immediately after planting. Rate based on soil texture, percent organic matter, and rainfall. Incorporate 2-3” into the soil within 24 hours of application and a second time in the opposite direction for best results. Take care not to bring untreated soil to the soil surface during re-incorporation.
Pre- and Postemergent Herbicides
- linuron (Lorox DF): PHI 45d for celery, 60d celeriac, REI 24h or 8d, Group 5. Apply 1.5-3 lb/A per application, only 1 application per year. Apply after the celery or celeriac has been transplanted and established, but before the crop is 8” tall. Only use on celery grown on muck soils. Do not exceed 40 psi spray nozzle pressure. Do not apply when temperatures exceed 85°F or as a tank mixture with surfactants, nitrogen or fertilizer solution, or other pesticides, as injury to the crop may result.
- prometryn (Caparol 4L): PHI 40d for celery, 60d for celeriac, REI 12h or 48h, Group 5. For celery, apply 2.4-3.2 pts/A before the crop emerges or 1.6-2 pts/A after the crop has emerged. Only 1 application per year. For celery seedbeds, direct seeded, and transplanted celery, apply broadcast after 2-5 celery leaves are present or 2-6 weeks after transplanting, before weeds are 2 inches tall. Apply in a minimum of 20 gal/A for direct seeded and transplanted celery. Apply in minimum 15 gal/A for seedbed, only after seedbed covers have been removed for a week. Do not apply if crop is under water stress. For celeriac, apply 1.6-4 pts/A per application, only 1 application per year. Do not exceed 4 pts/A per year. Apply over the top of the crop after it has 6-8 true leaves. Apply in a minimum of 20 gal/A of spray. Only 1 application per crop cycle and only 2 crop cycles on the same acre per year. Always apply before the weeds are 2” tall. Rate based on soil texture, 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.
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, 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” tall and rosettes less than 3” across.
- clethodim (Select Max): PHI 30d, REI 24hr, Group 1. Apply 9-16 oz/A per application, multiple applications allowed per year, a minimum of 14 days apart. Do not exceed 64 oz/A per year or 4 applications per year. Apply to actively growing grasses. Add 0.25% v:v nonionic surfactant (1 qt/100 gal of spray). Can also be used 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.
- pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0. Celery only. Apply a 3-10% solution (3-10 gallons per 100 gallons of spray). Rate is based on target weed species. Apply in 75-200 gal/A of spray. Can apply before planting, or as a directed and shielded spray during crop growth. Avoid contact with foliage or crop damage may occur. Spray to wet, but do not allow runoff of spray solution.
- sethoxydim (Poast): PHI 30d, REI 12h, Group 1. Celery only. Apply up to 1.5 pt/A per application, multiple applications allowed per year, a minimum of 14 days between applications. Do not exceed 3 pts/A per year. Apply to actively growing grasses. Rate is determined by weed species. 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 used 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.
Physiological Disorders
Blackheart
Blackheart is a physiological disorder akin to tipburn in other crops. It is associated with poor calcium assimilation as a result of inconsistent water uptake. Blackheart can be identified by the death of the growing points of the innermost petioles, or heart. Blackheart occurs in most celery growing regions, and significant losses have been reported in Florida, California, Texas, Utah and Wisconsin. If conditions favorable for the development of blackheart persist, the entire crown may be destroyed in a few days. In minor cases, the plants may recover or seem to recover, although symptoms can return. Symptom development is much more severe as plants approach maturity. The appearance of symptoms is closely linked to fluctuating water levels and available calcium. Environmental conditions that favor rapid growth, such as heavy rain or irrigation subsequent to drought, favor symptom development. High nitrogen, potassium, and sodium levels may also play a role. Certain celery cultivars are more susceptible to blackheart. Blackheart is prevented by ensuring steady plant growth, avoiding wide fluctuations in moisture and nutrients. Drench applications of soluble calcium can lessen or prevent the development of blackheart. Plant celery cultivars that are not prone to the syndrome. Drip irrigation, which provides more even moisture levels, can help reduce risk.