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.
Critical Period and General Information: For optimum growth and highest pepper yields, aim to keep production areas weed-free for the first 8-10 weeks after transplanting until pepper plants are large enough to be competitive with weeds.
Hairy galinsoga can be an issue in pepper production fields because this weed is not controlled by most herbicides registered for use in pepper and because it resists cultivation. Stale seed beds can help by encouraging and then killing off the initial flush of germinating galinsoga seeds. If galinsoga is an issue, rotate to crops where the use of herbicides that are known to control galinsoga are permitted (such as beets where Stinger can be applied, or sweet corn where atrazine herbicides are registered for use) to help reduce the number of short-lived galinsoga seeds in the soil.
Eliminate small patches of Solanaceous weeds, such as jimsonweed and horsenettle, prior to transplanting peppers because they are in the same plant family as pepper and can serve as alternate hosts and sources for disease and insect pests.
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)
- bensulide (Prefar 4E): REI 12h, Group 0. Apply 5-6 qt/A per application, only 1 application per year. Can be applied before or after planting, before the crop has emerged. Incorporate 1-2” into the soil with shallow cultivation if applying before planting or with water through irrigation or rainfall within 36 hours of application if applying after planting.
- clomazone (Command 3ME): REI 12h, Group 13. Apply 10.7-42.7 fl oz/A per application, only 1 application per year. Can be applied to the soil surface before seeding or transplanting, or after seeding but before crop emergence. Place seed or roots of the transplants below the chemical barrier when planting. Use the lower rate on sandy soils and the higher rate on silt and clay soils. Some temporary crop injury (partial whitening of leaf or stem tissue) may be visible after crop emergence. Complete recovery will occur from minor early injury without affecting yield or earliness. Do not use on banana peppers.
- napropamide (Devrinol 2-XT): REI 24h, Group 0. Apply 2-4 qt/A per application, only 1 application per year. Apply to direct seeded or transplanted crops to a weed-free soil surface. Can be applied before under plastic mulch or between rows of plastic mulch. Incorporate no deeper than the seeding depth through shallow cultivation. If soil is dry, incorporate 2-4” into the soil with water through irrigation or rainfall within 24-72 hours of application before covering with plastic. Apply plastic over treated soil the same day as incorporation. If applying between rows of plastic mulch, incorporate 1-2” into the soil with shallow cultivation or water through irrigation or rainfall within 24-72 hours of application. Use the lower rate on sandy soils and the higher rate on silt and clay soils.
- pendimethalin (Prowl H2O): PHI 70d, REI 24h, Group 3. Apply 1-3 pt/A per application, only 1 application per year. Can be applied as a broadcast surface application before transplanting crops, before laying plastic for raised beds, or in a band to previously untreated row middles between beds. Be sure not to overlap row and row-middle spray. Do not apply before direct-seeding. Can also be applied as a directed spray after planting transplants but do not apply to foliage of transplanted vegetables or severe injury may occur. Roots of transplants must be established. If applying after transplanting, mechanically incorporate the Prowl at blocking, thinning, or layby if sufficient rainfall or irrigation has not occurred.
- s-metolachlor (Dual Magnum): REI 24h, Group 15. MASSACHUSETTS, MAINE, and NEW HAMPSHIRE only: Transplanted bell pepper 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(link is external) 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.
- sulfentrazone (Aquesta 4F): REI 12h, Group 14. Apply 2.25-12 oz/A per application, only 1 application per year. Rate based on soil texture, organic matter and soil pH. Apply banded or broadcast before transplanting.
- trifluralin (Treflan HFP): REI 12h, Group 3. Transplants only. Apply 1-2 pt/A per application, only 1 application per year. Apply before transplanting. Incorporate 2-3’’ into the soil of the final seedbed within 24 hours of application. Disc twice after applying for satisfactory incorporation. Rate based on soil texture, percent organic matter, and rainfall. Poor weed control in soils that are wet or are subject to prolonged periods of flooding.
Pre- and Postemergence Herbicides
halosulfuron (Sandea): PHI 30d, REI 12h, Group 2. Apply 0.5-1 oz/A per application, multiple applications allowed per year. Do not exceed 2 oz/A per year. Apply to row middles only. Avoid contact of the herbicide and the planted crop. If plastic is used on the planted row, adjust equipment to keep the herbicide off the plastic.
Postemergent Herbicides (after weeds germinate)
- carfentrazone (Aim EC): PHI 0d, REI 12h, Group 14. Apply 0.5-2 oz/A per application. Do not exceed 6.1 oz/A per season. Can be applied as a preplant burndown no later than 7 days before seeding. Can also be applied 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 20d, REI 24h, Group 1. Apply 9-16 oz/A per application, up to 4 applications allowed 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.
- 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. Allow a minimum of 3 days between application and seeding and do not apply after seeding. 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.
- paraquat (Gramoxone SL 2.0*): restricted use. REI 12h or 24h, Group 22. Apply 1.3-2.7 pts/A per application, up to 3 applications allowed per year, a minimum of 14 days apart. Do not exceed 8 pts/A per year. Can be applied before, during, or after planting but before emergence. Can also be applied after the crop has emerged with a directed spray. 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...(link is external). 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). Apply in 75-200 gal/A of spray. Can use preplant, 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 20d, REI 12h, Group 1. Apply up to 1.5 pt/A per application, multiple applications allowed per year, a minimum of 14 days apart. Do not exceed 3 pts/A per year. 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.
Physiological Disorders
Sunscald
Sunscald occurs when the pepper fruit receives too much sun. Wide plant spacing and defoliation by bacterial spot may result in sunscald. Breakage of stems by pickers will also open the plant and result in sunscald. Promote good foliage growth with proper fertilization and irrigation during prolonged periods of hot weather. Staking plants can reduce lodging and sunscald.
Blossom End Rot
Blossom end rot is caused by flucuating soil moisture and movement of calcium in the plant. Symptoms begin as a sunken spots on the sides and blossom end of pepper, which can become infected with secondary fungi.