Strawberries
Diane Kaufman and Ed Peachey
Revised November 13, 2008

Weed control practices in strawberries must be timed to coincide with the crop’s nonreproductive phases or when minimal herbicide uptake can be expected. Strawberries can be induced into a nonreproductive “summer dormancy” by withholding water and fertilizer after harvest. Beds can be renovated by mowing old leaves, cultivating row middles, and sometimes applying an herbicide. In mid-August, plants are fertilized and watered to enhance flower bud development. Soil-applied herbicides can be applied at full rates in the fall. Sometimes, a foliar-active herbicide can be applied during the “summer” or “winter” dormancy when plants are completely inactive, if the grower is willing to accept the risk of crop injury.
Weed shifts  Although strawberries are rotated with other crops every 3 to 5 yr, some weed species may persist or increase with repeated use of the same or similar weed control practices, causing shifts in weed populations. Examples include deep-rooted perennials that survive cultivation, or weeds such as common groundsel that either resist the herbicide or are selected from a natural population of susceptible biotypes.
Preventing weed shifts  Weeds that survive cultivation, specific herbicide treatments, or other routine cultural practices must be eliminated before the tolerant species or biotypes become established. Combine a variety of weed control practices or treatments, rotate practices and herbicides, and spot-treat with a hoe or registered herbicide when a new weed first appears. Also, clean equipment when moving from an infested field.
Managing weeds in strawberry fields  Successful weed control in strawberry fields requires a comprehensive or year-round approach employing and alternating a combination of weed control practices over several years. Developing these strategies requires knowledge of each weed and weed control practice. Weeds must be identified and information gathered about the effectiveness of each weed control practice. Consider costs and select herbicide combinations that can be applied together or in split applications that control the weeds in the field. Note the action of each herbicide or how the chemical works in the plant. Then tank-mix and alternate use of these products to reduce the chance of developing resistant species or biotypes. Often, a combination of mechanical methods, herbicide treatments, and sometimes hand removal or spot treatment with herbicide sprays will provide the most effective year-round control.
Managing soil erosion   Band treatments of soil-active herbicides within the row. Planting annual cover crops such as spring barley or oats in row middles reduce water runoff and soil erosion on sloping land. Reduce herbicide amounts proportionately to the area of soil actually treated.
Soil-active herbicides  Persistent, soil-active herbicides can be applied in early fall through early spring and activated with rain or sprinkler irrigation if dry conditions persist. Apply lower rates on sandy soils having lower clay or organic matter contents to reduce or avoid possible injury symptoms. Existing vegetation between rows can be controlled with cultivation.
Postemergence herbicides  Contact herbicides or plant growth regulator herbicides such as 2,4-D can be used to control existing broadleaf weeds. 2,4-D controls many broadleaf weeds, but must be applied when weeds are actively growing. Strawberries must be completely inactive during the “summer” or “winter” dormancy to reduce the chance of crop injury from 2,4‑D.
Warning  Using 2,4-D or similar materials on horticultural farms involves risk, not only to the crop to which it is applied but also to other crops in nearby fields. However, there may be instances where guidance in using 2,4-D will enhance weed control with minimal chance for crop injury. Be careful to clean all 2,4-D from your equipment, or use separate sprayers before applying another product to other horticultural crops. Under no conditions should you use volatile formulations of 2,4-D or similar material. Purchase only a product that lists strawberries on the label.
Note  Herbicides must be applied at the correct rate and time to selectively control weed growth with minimal chance for injury to strawberries. Obtain more consistent results by reading the herbicide label and other information about the proper application and timing of each herbicide. Suggested rates listed in this guide are stated as pounds of active ingredient per acre (lb ai/A) or pounds of acid equivalent per acre (lb ae/A). For band applications over berry rows, reduce the amount of herbicide applied proportionately to the area within the row actually sprayed.
 STRAWBERRIES—New Plantings
•  glyphosate (Roundup Original)
Rate  Consult supplemental label
Time  Apply at least 3 days before transplanting.
Remarks  Do not apply within 2 days or after transplanting. Inhibits production of three amino acids and protein synthesis.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted.
•  napropamide (Devrinol 2EC)
Rate  4 lb ai/A (8 quarts/A Devrinol 2EC)
Time  Apply before weeds germinate or after cultivating to remove growing weeds.
Remarks  Requires sprinkler irrigation the same day to wet soil 2 to 4 inches deep. Applications during the growing season may delay or inhibit rooting (pegging) of runners. Some growers apply 2 lb ai/A at planting to minimize root pruning and pegging problems, then an additional 2 lb ai/A in fall. Inhibits root growth.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Acetamide
•  pendimethalin  (Prowl H2O)
first-year, nonbearing strawberries; Oregon and Washington
Rate  0.71 to 1.4 lb ai/A (1.5 to 3 pints/A Prowl H2O)
Time  Special local need labels OR-060007 and WA-060018. Apply preemergence as a broadcast spray to the soil surface before or within 7 days after transplanting strawberries. 
Remarks  Most effective if rain or irrigation incorporates herbicide into weed emergence zone within 7 days. Do not apply to strawberry bed if bed is later to be covered with plastic. 
Caution  Stunting, reduced growth, or reduction in daughter plants may result. Refer to main labels for crop rotation restrictions.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  DCPA (Dacthal Flowable)
Rate  9 lb ai/A (12 pints/A)
Time  Apply soon after transplanting or preplant incorporate. Inhibits mitosis.
Remarks  Applications west of Cascades usually perform erratically.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Phthalic acid
•  lactofen (Cobra)
nonbearing in Oregon only
Rate 0.25 to 0.38 lb ai/A (16 to 24 oz/A)
Time  Apply immediately before or after transplanting or within 48 hr after transplanting if soil is placed over plants to minimize contact and possible injury.
Remarks  Special local needs label OR-010006. Activate with 0.25 to 0.5 inch water within 48 hr. Grasses are not controlled. Preharvest interval is 1 yr.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Diphenylether
•  sethoxydim (Poast)
Rate  0.19 to 0.47 lb ai/A (2 to 2.5 pints Poast/A)
Time  Apply at optimum growth stage listed on label.
Remarks  Identify susceptible grasses and add 2 pints/A of a nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues, but quackgrass can be suppressed. Inhibits fatty acid production, cell membranes, and new growth.
Caution  Do not exceed 2.5 pints/A per season. 
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clethodim (Envoy or Select 2EC)
Rate  0.09 to 0.125 lb ai/A(6 to 8 oz/A Select 2EC)
Time  Apply postemergence to actively growing annual or perennial grasses, including annual bluegrass, as listed on label. 
Remarks  Consider environmental and plant growth conditions that affect leaf uptake; see label for guidelines. Limited observations suggest that April treatments may cause slight cupping and browning of petals or blossoms. Add crop oil concentrate as described on label.
Caution  Do not exceed 68 fl oz/A Envoy or 32 oz/A Select per season.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  carfentrazone-ethyl (Aim EC)
Rate  May be applied to row middles only at rates up to 0.031 lb ai/A (2 fl oz/A Aim EC) broadcast per application in at least 10 gal/A of finished spray. See label for rate based on target weed species.
Time  Apply postemergence to actively growing broadleaf weeds, as listed on label.
Remarks  Controls listed broadleaf weeds up to 4 inches tall. Will not control grass weeds. A nonionic surfactant, methylated seed oil, or crop oil concentrate is required. Consult label for adjuvant selection and instructions.
Caution  Apply to row middles only, using a shielded or hooded sprayer that prevents any spray from contacting strawberry plant tissues. Crop will be injured if spray contacts green stem tissues, leaves, blooms, or fruit. See label for hooded or shielded sprayer directions. Do not exceed 6.1 fl oz/A broadcast (0.096 lb ai/A) per season as a row-middle application.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Triazinone
•  flumioxazin (Chateau)
Rate  0.096 lb ai/A (3 oz/A Chateau)
Time  Preplant. For preemergence weed control, apply at least 30 days before transplanting and before plastic mulch (if used) is laid. In established plantings in spring or summer, apply to row middles only, using a hooded or shielded sprayer before weeds emerge. Do not let spray drift contact strawberry plant foliage.
Remarks  May provide some burnback of existing broadleaf weeds. Adding an adjuvant enhances weed burnback but may lead to crop spotting.
Caution  Do not exceed 3 oz/A at this timing. Do not apply after fruit set or when fruit is present.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  N-phenylphthalimide

STRAWBERRIES—Established Plantings—Early Fall or Winter Applications
Cereal Interplant  On sloping land, spring cereals such as barley or oats are sown between rows to reduce or slow runoff and possible erosion. The cereals are killed in spring with cultivation or herbicides before excessive growth.
•  simazine (Princep 4L)
Oregon and Washington only
Rate 1 lb ai/A (1 quart/A Princep 4L)
Time  Apply after harvest at time of bed renovation where overhead irrigation is available for activation, or apply in October or November and activate with rain. Apply only once per year and do not use on sandy or coarse soils. 
Remarks  Established weed seedlings will not be controlled.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazine
•  terbacil (Sinbar)
Rate  0.1 to 0.3 lb ai/A (2 to 6 oz Sinbar/A)
Time  Apply during winter dormancy, before weeds are 2 inches tall or wide. Apply split treatments of up to 0.3 lb ai/A during bed renovation and again in winter; do not exceed 0.4 lb ai/A (8 oz/A) per year. Apply to strawberries established at least 6 mo.
Caution  Do not use on sandy, loamy sands, gravelly soils or soils containing less than 2% organic matter. Avoid use for 2 yr if replanting is planned, and consult label for recropping information. 
Site of action  Group 5: photosystem II inhibitor
Chemical family  Uracil
•  napropamide (Devrinol 2EC)
Rate  4 lb ai/A (8 quarts/A Devrinol 2EC)
Time  Apply fall through early spring before weeds emerge, preferably in November or December.
Remarks  If applied March through October, requires sprinkler irrigation to wet soil 2 to 4 inches deep to reduce herbicide degradation. Due to possible carryover in wheat rotations, use other weed controls the final year of strawberry production, or plow deeply to dilute soil residue. Inhibits root growth.
Caution  Do not exceed 4 lb ai/A per year. 
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Acetamide
•  pendimethalin (Prowl H2O)
Rate  0.71 to 1.4 lb ai/A (1.5 to 3 pints/A Prowl H2O)
Time  May be applied to strawberries in fall or winter dormancy, but prior to onset of new seasonal growth from crowns.
Caution  Do not apply if new leaves have emerged or are exposed. Stunting, reduced growth, or reduction in daughter plants may result. Refer to main labels for crop rotation restrictions. Preharvest interval is 35 days.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  DCPA (Dacthal Flowable)
Rate  6 to 9 lb ai/A (8 to 12 pints/A Dacthal Flowable)
Remarks  Applications west of Cascades usually perform erratically. Elsewhere, apply in fall or early spring to control late summer weeds. Inhibits mitosis.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Phthalic acid
•  sethoxydim (Poast)
Rate  0.38 to 0.48 lb ai/A (2 to 2.5 pints/A)
Time  Apply at optimum growth stage listed on label. 
Remarks  Identify susceptible grasses; add 2 pints/A of a nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues; quackgrass can be suppressed. Note special precautions on Sinbar applications. 
Caution  Do not exceed 2.5 pints/A per season. Preharvest interval is 7 days. Inhibits fatty acid production, cell membranes, and new growth.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clethodim (Select)
Rate  0.09 to 0.125 lb ai/A (6 to 8 oz/A Select 2EC). Consult label for rate required to control different grasses.
Time  Apply to actively growing grasses at recommended heights.
Remarks  Add crop oil concentrate as described on label.
Caution  Do not exceed 8 fl oz/A per treatment or 32 fl oz/A per season. Preharvest interval is 4 days.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clopyralid (Stinger)
Oregon and Washington only
Rate  0.125 lb ai/A (0.33 pint/A Stinger) 
Time  Apply after harvest, from September 15 to November 15. 
Remarks  Special local needs labels OR-030031 and WA-030035. Requires signing a waiver of liability. 
Caution  Do not exceed a total of 0.25 lb ai/A (0.66 pint/A) per year. Do not use with surfactants or tank-mix with other herbicides. May cause minor leaf cupping. Do not compost vegetation treated with Stinger.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  carfentrazone-ethyl (Aim EC)
Rate  May be applied only to row middles at rates up to 0.031 lb ai/A (2 fl oz/A Aim EC) broadcast per application in at least 10 gal/A of finished spray. See label for rate based on target weed species.
Time  Apply postemergence to actively growing broadleaf weeds, as listed on label.
Remarks  Controls listed broadleaf weeds up to 4 inches tall. Will not control grass weeds. A nonionic surfactant, methylated seed oil, or crop oil concentrate is required. See label for adjuvant selection and instructions.
Caution  Apply only to row middles, using a shielded or hooded sprayer that prevents any spray from contacting strawberry plant tissues. Crop will be injured if spray contacts green stem tissues, leaves, blooms, or fruit. See label for hooded or shielded sprayer directions. Do not exceed 6.1 fl oz/A broadcast (0.096 lb ai/A) per season as a row-middle application. 
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Triazinone
•  flumioxazin (Chateau)
Rate  0.096 lb ai/A (3 oz/A Chateau)
Time  Apply during winter dormancy for preemergence weed control.
Remarks  May provide some burnback of existing broadleaf weeds. Experience indicates 2.2 oz/A is sufficient for preemergence weed control. Crop oil concentrate, at 1% v/v, or nonionic surfactant, at 0.25% v/v, may be added to help control emerged broadleaf weeds.
Caution  Do not exceed 3 oz/A Chateau at this timing.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  N-phenylphthalimide
STRAWBERRIES—Established Plantings—Weed Control in Late Winter and Spring
•  clopyralid (Stinger)
Oregon and Washington only
Rate  0.125 lb ai/A (0.33 pint/A Stinger)
Time  Apply in spring, before first bloom.
Remarks  Special local needs labels OR-030031 and WA-030035. Requires signing a waiver of liability.
Caution  Do not exceed a total of 0.25 lb ai/A (0.66 pint/A) per year. Do not use with surfactants or tank-mix with other herbicides. May cause minor leaf cupping. Do not compost vegetation treated with Stinger. Preharvest interval is 30 days.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  2,4-D (Formula 40 or others)
Rate  0.9 to 1.4 lb ae/A (1 to 1.5 quarts/A Formula 40)
Time  Apply in late winter when crops are dormant, in 20 to 25 gal/A water. Apply before February to mitigate potential injury to fruit.
Remarks  Make sure label includes strawberries; follow directions carefully. Triple-rinse and wash spray tank with appropriate cleaners before applying herbicides to other crops.
Caution  Do not use unless possible crop injury is acceptable. Avoid using under conditions that favor drift or movement to susceptible crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  carfentrazone-ethyl (Aim EC)
Rate  Apply only to row middles at rates up to 0.031 lb ai/A (2 fl oz/A Aim EC); broadcast per application in at least 10 gal/A of finished spray. See label for rate based on target weed species.
Time  Apply postemergence to actively growing broadleaf weeds, as listed on label.
Remarks  Controls listed broadleaf weeds up to 4 inches tall. Will not control grass weeds. A nonionic surfactant, methylated seed oil, or crop oil concentrate is required. Consult label for adjuvant selection and instructions.
Caution  Apply only to row middles, using a shielded or hooded sprayer that prevents any spray from contacting strawberry plant tissues. Crop will be injured if spray contacts green stem tissues, leaves, blooms, or fruit. See label for hooded or shielded sprayer directions. Do not exceed 6.1 fl oz/A broadcast (0.096 lb ai/A) per season as a row-middle application. 
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Triazinone
•  flumioxazin (Chateau)
Rate  0.096 lb ai/A (3 oz/A Chateau)
Time  Apply in early spring before weed emergence and fruit set.
Remarks  Apply only to row middles using a hooded or shielded sprayer. May give some burnback of existing broadleaf weeds. Adding an adjuvant enhances weed burnback but may lead to crop spotting.
Caution  Do not exceed 3 oz/A per application. Do not apply over strawberries. Do not let spray drift contact fruit or foliage.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  N-phenylphthalimide
•  pendimethalin (Prowl H2O)
Rate  0.71 to 1.4 lb ai/A (1.5 to 3 pints/A Prowl H2O)
Time  May be applied to strawberries in winter dormancy prior to onset of new seasonal growth from crowns, or in spring as a band between rows.
Caution  Do not apply if new leaves have emerged or are exposed. Stunting, reduced growth, or reduction in daughter plants may result. Refer to main labels for crop rotation restrictions. Preharvest interval is 35 days.
Site of action  Group 3: microtubule assembly inhibitor.
Chemical family  Dinitroaniline 
STRAWBERRIES—Established Plantings—Weed Control during Bed Renovation in Summer
Cultivation  After harvest, withhold irrigation to induce “summer dormancy” before treating perennial weeds. Cultivate row middles to reduce runners and control weeds.
•  simazine (Princep 4L)
Oregon and Washington only
Rate  1 lb ai/A (1 quart/A Princep 4L)
Time  Apply after bed renovation and first irrigation followed with additional 0.5 inch irrigation to activate the herbicide. Apply only once per year.
Remarks  In summer, simazine is only about half as active as in winter applications.
Caution  Do not apply on sandy soils.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Triazine
•  terbacil (Sinbar)
Rate  0.2 to 0.4 lb ai/A (4 to 8 oz/A Sinbar)
Time  Apply to strawberries established at least 6 mo.
Remarks  Avoid use for 2 yr if replanting is planned; consult label for recropping information. Split applications at lower rates are preferred after bed renovation in summer, before new strawberry growth begins, and before weeds are more than 2 inches tall or wide.
Caution  Do not exceed 0.4 lb ai/A (8 oz/A per year) or use on sandy, loamy sands, gravelly soils, or soils with less than 2% organic matter. Inhibits photosynthesis.
Site of action  Group 5: photosystem II inhibitor
Chemical family  Uracil
•  napropamide (Devrinol 2-EC)
Rate  4 lb ai/A (8 quarts/A Devrinol 2EC)
Time  Apply to weed-free soil after bed renovation.
Remarks  Prevents daughter plants from rooting.
Caution  Do not exceed 4 lb ai/A per year. Inhibits root growth.
Site of action  Group 15: inhibits very long chain fatty acid synthesis
Chemical family  Acetamide
•  paraquat (Gramoxone Inteon)
Rate  0.5 lb ai/A (2 pints Gramoxone Inteon/A)
Time  Apply as a directed spray between rows, using shields to prevent spray contact with crop.
Remarks  Add nonionic surfactant or crop oil concentrate as label directs; avoid anionic formulations that react to form insoluble precipitates. Acts as contact; absorbs energy produced by photosynthesis, forming peroxides that disrupt living cells.
Caution  A restricted-use pesticide. Do not inhale or ingest spray mist. Wear protective face shields, respirators, and clothing. Do not exceed three applications a year. Preharvest interval is 21 days. 
Site of action  Group 22: photosystem I electron diversion
Chemical family  Bipyridilium
•  sethoxydim (Poast)
Rate  0.38 to 0.47 lb ai/A (2 to 2.5 pints/A)
Time  Apply at optimum growth stage listed on label.
Remarks  Identify susceptible grasses; add 2 pints/A of a nonphytotoxic crop oil concentrate to improve leaf absorption. Control often is erratic on grasses stunted or stressed from drought, high temperatures, or low fertility. Resistant grasses include annual bluegrass and all fine fescues; quackgrass can be suppressed. Inhibits fatty acid production, cell membranes, and new growth.
Caution  Do not exceed 2.5 pints/A per season. Note special precautions on Sinbar applications based on crop injury experienced in other regions; never tank-mix Sinbar with Poast, and do wait at least 2 wk between applying these herbicides. Preharvest interval is 7 days.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  clethodim (Select 2EC)
Rate  0.09 to 0.125 lb ai/A (6 to 8 oz/A Select 2EC)
Time  Apply to actively growing grasses at recommended weed heights.
Remarks  Add crop oil concentrate as described on label.
Caution  Do not exceed 8 fl oz/A per treatment or 32 fl oz/A per season.
Site of action  Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family  Cyclohexanedione
•  carfentrazone-ethyl (Aim EC)
Rate  Apply only to row middles at rates up to 0.031 lb ai/A (2 fl oz/A Aim EC) broadcast per application in at least 10 gal/A of finished spray. See label for rate based on target weed species.
Time  Apply postemergence to actively growing broadleaf weeds, as listed on label.
Remarks  Controls listed broadleaf weeds up to 4 inches tall. Will not control grass weeds. A nonionic surfactant, methylated seed oil, or crop oil concentrate is required. Consult label for adjuvant selection and instructions.
Caution  Apply only to row middles, using a shielded or hooded sprayer that prevents any spray from contacting strawberry plant tissues. Crop will be injured if spray contacts green stem tissues, leaves, blooms, or fruit. See label for hooded or shielded sprayer directions. Do not exceed 6.1 fl oz/A broadcast (0.096 lb ai/A) per season as a row-middle application.
Site of action  Group 14: protoporphyrinogen oxidase inhibitor
Chemical family  Triazinone
•  pendimethalin (Prowl H2O)
Rate  0.71 to 1.4 lb ai/A (1.5 to 3 pints/A Prowl H2O)
Time  During renovation when no foliage is exposed.
Caution  Do not apply if new leaves have emerged or are exposed. Stunting, reduced growth, or reduction in daughter plants may result. Refer to main labels for crop rotation restrictions. Preharvest interval is 35 days.
Site of action  Group 3: microtubule assembly inhibitor
Chemical family  Dinitroaniline
•  2,4-D (Formula 40 or others)
Rate  0.9 to 1.4 lb ae/A (1 to 1.5 quarts/A Formula 40)
Time  Apply immediately after last harvest, in 20 to 25 gal/A water. 
Remarks  Make sure the label includes strawberries, and follow directions carefully. Triple-rinse and wash spray tank with appropriate cleaners before applying herbicides to other crops.
Caution  Do not use unless possible crop injury is acceptable. Avoid use under conditions that favor drift or movement to susceptible crops.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid