Weed Control

Weeds may develop quickly because beans are slow to establish a canopy. Use a tine-weeder or a rotary hoe if there is not too much field residue for pre-emergent mechanical weed control. Do not cultivate when the beans are starting to emerge as seedlings are very fragile and can easily snap. Cultivate 3 to 4 times when beans are 2 to 3 inches tall until canopy closure. Bean taproots are easily torn from the ground during imprecise mechanical cultivation. To minimize damage to plants, do not cultivate when leaves are wet or just after they have flowered.

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 for information on the use of these herbicides or flaming. 

  • carfentrazone (Aim EC): PHI 0d, REI 12h, Group 14. 
  • 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)

clomazone (Command 3ME): PHI 45d, REI 12h, Group 13. Apply 6.4-10.7 oz/A per application, only 1 application allowed per year. For lima beans, apply 6 oz/A per application, up to 2 applications allowed per year, a minimum of 14 days apart. Do not exceed 10.7 oz/A per year. Rate based on soil texture, use lower rate on coarse soils. Can be applied to the soil surface after seeding or transplanting but before crop emergence, in a minimum of 10 gal/A of spray. Be sure to place seeds or roots below the treated soil when planting. 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.

dimethenamid (Outlook): REI 12h, Group 15. For dry beans only. Apply 7-14 oz/A, up to 2 applications allowed per year, a minimum of 14 days apart. Do not exceed 21 oz/A per year. Has not been tested on all varieties, crop tolerance should be verified before treating the entire field. If applying as a split application, apply 10-14 oz/A at the first application and the remaining 7-11 oz/A at the second application. Application rate depends on soil texture and organic matter content. If split applications are less than 14 days apart, the maximum rate is dependent on soil texture. Apply to the soil up to 45 days before planting. If applying 15-45 days before planting, use a higher rate and apply to the soil as part of a split-application program where the second application is made after planting. If applying less than 15 days before planting or after planting but before crop emergence, incorporate 1-2” into the soil with shallow cultivation or with water through irrigation or rainfall. Can also apply to the soil surface without incorporating when the crop is between the 1st-3rd trifoliate stage. If soil is saturated for an extended period, temporary growth suppression, spotting, or browning may occur.

EPTC (Eptam 7E): PHI 45d, REI 12h, Group 15. Apply 3.5-4.5 pts/A per application. Can be applied just before or immediately after planting, or as a directed spray to the base of the plant at layby before pods start to form. Can also be applied as a subsurface application at 2.25 pts/A before planting or at 1.75 pts/A at layby (as long as a clean cultivation has been made first). Has not been tested on all varieties, crop tolerance should be verified before treating the entire field. Lima beans and green beans grown on sandy soil may be less tolerant.

ethalfluralin (Sonalan HFP): REI 24h, Group 3. Apply 1.5-4.5 pts/A per application. Do not exceed 2-4.5 p/A per year. Rate based on soil texture and weed composition. Apply and incorporate 2-3” into the soil in the fall or spring before planting. Can also apply immediately after tillage and planting. Incorporate with 0.5-1” of water through irrigation or rainfall. The maximum application rate when incorporating with overhead irrigation incorporation is 3.7 pts/A and with rainfall is 2 pts/A.

linuron (Lorox DF): REI 24h or 48h, Group 5. Apply up to 2 lbs/A per application, only 1 application per year. Apply after seeding but before crop emergence. Incorporate into the soil with water through irrigation or rainfall.

pendimethalin (Prowl H2O): REI 24h, Group 3. Apply 2-3 pt/A per application, only 1 application per year. Rate based on soil texture. Apply in the fall or spring before seeding and incorporate 2-3" into the soil.

s-metolachlor (Dual Magnum): REI 24h, Group 15. Apply 1-2 pts/A per application, multiple applications allowed per year, a minimum of 14 days apart. Do not exceed 2 pts/A per year. Rate based on application timing, soil texture, and organic matter content. Apply up to 14 days before planting and incorporate 2” into the soil or apply to the soil surface just after seeding before crop emerges. Can also apply after the 1st trifoliate stage of bean growth although leaf spotting may occur. Use of tank mixes, where the rate of metolachlor could be lowered, will decrease the likelihood of crop injury. Risk increases on light-textured soils and under wet conditions.

sulfentrazone (Aquesta 4F): REI 12h, Group 14. Apply 2.25-8 oz/A per application, only 1 application allowed per year. Rate based on soil texture, organic matter, soil pH, and application timing. Apply to soil surface in the fall or spring from 60 days prior to planting up to 3 days after planting (if seed furrow is completely closed and if seedlings have not broken the soil furrow). If applying in the fall, do not incorporate into the soil. If applying in the spring 3 weeks prior to planting, use a higher application rate. Wait a minimum of 7 days after application before planting in coarse-textured soil with less than 1.5% organic matter. If dry conditions persist after application, a shallow incorporation may be needed (less than 2” deep).

trifluralin (Treflan HFP): REI 12h, Group 3. Apply 1-2 pts/A per application, only 1 application allowed per year. Rate based on soil texture, percent organic matter, rainfall, and type of bean. 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

formesafen (Reflex)PHI 45d for dry beans 30d for snap beans, REI 24h, Group 14. Apply 1.25 pts/A per application, up to 2 applications allowed per year. Do not exceed 1.25 pts/A per year. Applications can only be made on alternate years. Can be applied to the soil before or after planting or when beans have at least 1 fully expanded trifoliate leaf. Some bronzing may occur but should not affect yield.

halosulfuron (Sandea)PHI 30d, REI 12h, Group 2. Apply 0.5-1 oz/A per application. Do not exceed 2 oz/A per year, but only 1 oz/A per crop cycle. Rates vary based on crop, application timing, and soil texture. Has not been tested on all varieties, crop tolerance should be verified before treating the entire field. Can be applied after seeding and before soil cracking, or for succulent beans, apply before planting and incorporate 2” into the soil. Can cause temporary stunting in succulent beans. Can also apply when plants have 1-3 trifoliate leaves for dry bean and 2-4 trifoliate leaves for succulent beans, but before flowering. Make only 1 broadcast application per season. Directed sprays can limit crop injury. Can also apply to row middles but avoid contact with the crop. Heavy rains following application or organophosphate use will increase the potential for crop injury.

Postemergent Herbicides (after weeds germinate)

bentazon (Basagran): PHI 30d, REI 48h, Group 6.  Apply 0.8-1.6 pts/A per application. Rate based on weed composition. Apply to actively growing weeds. Apply after the 1st trifoliate leaf has fully expanded. An effective treatment in an emergency situation to control certain broadleaf weeds and fairly effective against yellow nutsedge when 4-6" tall. Yellowing and leaf speckling may occur on leaves but should not affect yield. If applying with a crop oil concentrate, injury may increase and may reduce yields.

carfentrazone-ethyl (Aim EC): PHI 0d, 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 year. Can be applied as a preplant burndown no later than 1 day before planting. Can also be applied 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 21d, REI 24h, Group 1. Apply 9-16 oz/A per application, only 1 application per year. 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 to 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 60d, REI 12h, Group 1.  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. Rate based on weed composition. Add either crop oil concentrate (0.5-1%, 0.5-1 gal/100 gal of spray) or nonionic surfactant (0.25-0.5%, 1-2 qt/100 gal of spray).

glyphosate (Roundup Power Max): PHI 7d, REI 4h, Group 9. Apply 15 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, before crop has emerged, or as a spot treatment for dry bean varieties. Only 1 spot treatment application allowed per year. Do not combine spot treatment and preharvest applications on the same crop. 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.

imazamox (Raptor): REI 4h, Group 2. Apply up to 4 oz/A per application, only 1 application per year. For dry and snap beans, apply after beans have 1 fully expanded trifoliate leaf but before bloom. For lima beans, apply when beans have 1-2 trifoliate leaves stage and weeds are less than 3” tall. A nonionic surfactant must be added to the spray solution. Apply at least 1 hour before rainfall or overhead irrigation. For snap and lima beans, may cause shortened internode length, reduce crop growth, quality, or yield. Has not been tested on all varieties, crop tolerance should be verified before treating the entire field.

paraquat (Gramoxone SL 2.0*): restricted use. REI 12h or 24h, Group 22. For snap and dry beans only. For lima beans, apply 1.3-2.7 pts/A per application. For dry beans, apply 0.8-1.3 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 for lima beans and 1.3 pts/A per year for dry beans. 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 gal per 100 gal). 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 after harvest.

quizalofop (Assure II): PHI 30d for dry beans, 15d for snap beans, REI 12h, Group 1. Apply up to 4-12 oz/A per application, up to 2 applications allowed per year, a minimum of 7 days apart. For dry beans, do not exceed 24 oz/A per year. For snap beans do not exceed 14 oz/A per year. Rate based on weed composition and growth stage. Apply with either crop oil concentrate or non-ionic surfactant. Do not apply when crop or weeds are under drought stress.

sethoxydim (Poast): PHI 30d for dry beans, 15d for snap beans, REI 12h, Group 1. Apply up to 2.5 pt/A per application, multiple applications allowed per year, a minimum 14 days apart. Do not exceed 4 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% (1.3-1.9 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.