Weed Control : New England Vegetable Management Guide : UMass Amherst

Bean - General Bean Disease Control Bean Insect 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. Do not cultivate when the beans are starting to emerge as seedlings are very fragile and can easily snap. Cultivate 3-4 times when beans are 2-3 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.

Stale Seedbed

The following herbicides are nonselective and are used to control weeds which are present in a field prior to planting or before the crop emerges, which is especially useful for the Stale Seedbed Technique (see the Weed Management section for more information).

glyphosate (Roundup Power Max): PHI 7d, REI 4h, Group 9.
paraquat (Gramoxone SL 2.0*): REI 48h, Group 22. *Restricted use: Applicators must complete an EPA-approved paraquat training every 3 years: https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators.
pelargonic acid (Scythe): PHI 1d, REI 12h, Group 0.

Preemergent Herbicides (before weeds germinate)

HRAC Group 3:

ethalfluralin (Sonalan HFP): 1.5 to 4.5 pt/A. REI 24h. Dried shelled beans only. 1 application per year. Apply in the fall with dry bulk fertilizer, or spring before planting.
pendimethalin (Prowl H2O): 2 to 3 pt/A. PHI 60d, REI 24h. Apply and incorporate prior to planting. Do not apply when air temperature is below 45°F. Contact with crop will cause damage.
trifluralin (Treflan HFP): 1 to 2 pt/A. REI 12h. 1 application per year. Apply in the fall or in the spring before planting and incorporate in less than 24 hours. A second incorporation pass in the opposite direction may be required.

HRAC Group 13:

clomazone (Command 3ME): 6.4 to 10.7 fl oz/A. PHI 45d, REI 12h. Snap beans only. 1 application per year. Apply before or after seeding but before emergence. Temporary partial whitening of leaf or stem tissue may occur but should not affect yield.

HRAC Group 14:

sulfentrazone (Aquesta 4F): 2.25 to 8 fl oz/A. PHI 0d, REI 12h. Dry beans only. Do not exceed 8 fl oz/A per year. Can be split-applied. Apply in the spring from 60 days prior to planting up to 3 days after planting. Do not apply if seeds or seedlings are less than 1” below the soil surface.

HRAC Group 15:

dimethenamid (Outlook): 7 to 21 fl oz/A. PHI 70d, REI 12h. Dry beans only. Do not exceed 21 fl oz/A per year. Can be split-applied. Apply before or after planting before the crop has emerged or when the crop has 1 to 3 trifoliate leaves. Saturated soil or contact with the crop can cause spotting or browning, but should not impact yield.
EPTC (Eptam 7E): 3.5 to 4.5 pt/A. REI 12h. Dry and green beans only. Do not exceed 9.75 pt/A per year. Apply before or after planting before the crop has emerged or as a directed spray to the base of the plant at layby before pods start to form.
s-metolachlor (Dual Magnum): 1 to 2 pt/A. PHI 50d, REI 24h. Do not exceed 2 pt/A per year. Apply before or after planting before the crop has emerged or after the crop has the 1st trifoliate leaf, although leaf spotting may occur. Do not use an adjuvant when applied after crop emergence.

Pre- and Postemergent Herbicides

HRAC Group 2:

halosulfuron (Sandea): 0.5 to 1 oz/A. PHI 30d, REI 12h. Do not exceed 2 oz/A per year. Apply before planting for succulent beans or after seeding and before soil cracking for all beans. Can also apply when plants have 1 to 3 trifoliate leaves for dry beans and 2 to 4 trifoliate leaves for succulent beans, but before flowering. Over-the-top applications can cause temporary stunting in succulent beans. Heavy rains following application or organophosphate use will increase the potential for crop injury.

HRAC Group 14:

formesafen (Reflex): 1.25 pt/A. PHI 45d for dry beans, 30d for snap beans, REI 12h. Dry and snap beans only. Do not exceed 1.25 pt/A per year. Applications can only be made on alternate years. Apply before or after planting before the crop has emerged or after the crop has at least 1 trifoliate leaf. Some leaf spotting may occur when sprayed after crop emergence or when treated soil splashes up onto emerged seedlings. Do not use UAN or ammonium sulfate.

Postemergent Herbicides (after weeds germinate)

HRAC Group 0:

pelargonic acid (Scythe): 3 to 10% solution. PHI 1d, REI 12h. Apply for vegetative burndown during site preparation, prior to crop emergence from soil, or as a directed and shielded spray. Contact with crop will cause damage.

HRAC Group 1:

clethodim (Select Max): 9 to 32 fl oz/A. PHI 30d, REI 24h. Do not exceed 64 fl oz/A per year. Apply to actively growing grasses.
fluazifop (Fusilade DX): 6 to 24 fl oz/A. PHI 60d, REI 12h. Dry beans only. Do not exceed 48 fl oz/A. Apply to actively growing grasses.
quizalofop (Assure II): 4 to 12 oz/A. PHI 30d, REI 12h. Do not exceed 14 oz/A per year. Apply to actively growing grasses.
sethoxydim (Poast): 2.5 pt/A. PHI 30d dry beans, 15 days succulent beans, REI 12h. Do not exceed 4 pt/A per year. Apply to actively growing grasses. BASF has stopped production and will discontinue the registration at the end of 2027.

HRAC Group 2:

imazamox (Raptor): 4 oz/A. PHI 0d, REI 4h. 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 to 2 trifoliate leaves. Must be applied with Basagran to lima beans. May cause reduced crop growth, quality, or yield of all beans.

HRAC Group 6:

bentazon (Basagran): 0.8 to 1.6 pt/A. PHI 30d, REI 48h. Apply to actively growing weeds. Apply after the 1st trifoliate leaf has fully expanded. Fairly effective against yellow nutsedge when 4 to 6" tall. Yellowing and leaf speckling may occur on leaves but should not affect yield.

HRAC Group 9:

glyphosate (Roundup Power Max): 10 fl oz to 3.1 qt/A. PHI 7d, REI 4h. Do not exceed 5 qt/A per year. Apply during fallow intervals, prior to planting, at planting, before crop has emerged, or to row middles with a hooded or shielded sprayer or wiper applicator. For dry beans can also spot treat or use preharvest, but do not use both on the same field in the same year. Spray contact can cause plant death. Spray additive recommendation varies with formulation–see label.

HRAC Group 14:

carfentrazone-ethyl (Aim EC): 0.5 to 4 fl oz/A. PHI 0d, REI 12h. Do not exceed 6.1 fl oz/A per year. Apply as a pre-plant burn-down up to 7 days before seeding or 1 day before transplanting, to row middles of emerged crop with hooded sprayer, or in dry beans as a harvest aid. Contact with crop will cause damage.
flumioxazin (Chateau EZ): 3 fl oz/A. PHI 5d, REI 12h. Harvest aid in dry beans only. 1 application per year. Must use an adjuvant. Apply over the top when beans have reached physiological maturity.
saflufenacil (Sharpen): 1 to 2 fl oz/A. PHI 2d, REI 12h. Harvest aid in dry beans only. Do not exceed 2 fl oz/A. Apply over the top when beans have reached physiological maturity.

HRAC Group 22:

paraquat (Gramoxone SL 2.0*): 1.3 to 2.7 pt/A for lima and snap beans, 0.8 to 1.3 pt/A for dry beans. PHI 7d, REI 48h. Do not exceed 8 pt/A per year for lima and snap beans and 1.3 pt/A per year for dry beans. Can be used as a harvest aid in dry beans. May be fatal if swallowed or inhaled. *Restricted use: Applicators must complete an EPA-approved paraquat training every 3 years: https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators.