clethodim (Select Max and others)
Rate 0.068 to 0.121 lb ai/A (9 to 16 oz/A Select Max)
Time Apply postemergence to actively growing annual or perennial grasses as listed on label.
Remarks Consider environmental and plant growth conditions that affect leaf uptake (see label for guidelines).
Caution Do not exceed 64 fl oz/A per season. Do not apply directly over the top of fruit or nut crops that may be used for rootstock, because crops may be injured.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione
geo-textiles
Available at agriculture and garden supply stores
Spunbonded fabrics (nonwoven) lightweight, extruded polypropylene fibers. Require mulch cover due to moderate UV light sensitivity. Weed roots and rhizomes can penetrate fabric unless removed before establishment. Cheapest option.
Woven fabrics moderate-weight polypropylene fibers woven into a mat. Can be used without mulch cover due to UV light stability. Weed roots and rhizomes can penetrate fabric, although tightness of weave can prevent some weeds. Moderate cost.
Laminates highly porous, dense poly film bonded to capillary fibers with a pressed, nonwoven bottom layer. The slick surface wets and dries rapidly, which prevents weed establishment, except for perennial rhizomes which can penetrate the laminate. Most expensive geo-fabric.
glyphosate (numerous product names)
Rate Read label carefully for crops listed and geographic location.
Time Apply to actively growing weeds.
Remarks Additional surfactant or ammonium sulfate according to label instructions may improve control of slightly stressed weeds. Adjust concentration depending on equipment, or consult label about rate and time of application, especially for perennial weeds. Select application equipment to prevent crop injury, by directing spray or by using selective applicators.
Caution Do not let spray or mist contact foliage, green bark, suckers, or other parts of trees. Contact with other than natural brown bark can seriously damage crop. Grazing is prohibited. Inhibits production of three amino acids and protein synthesis.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
glyphosate (several products)
Rate Wiper: 33% solution
Time Apply 1 gal product with 2 gal water and wipe weeds, avoiding contact with desirable vegetation.
Remarks In severe infestations, reduce equipment ground speed or apply in two directions to ensure contact with wiper. (See remarks above.)
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
glufosinate ammonium (Rely 280)
Rate 0.88 to 1.46 lb ai/A (1.5 to 2.5 quarts/A Rely 280 or generic equivalent)
Time Apply to actively growing weeds as a directed spray or spot treatment according to stage of weed growth.
Remarks Avoid drift onto, or treatment of desirable foliage or green bark during establishment year. Only trunks with calloused brown bark should be sprayed, unless they are protected with grow tubes or waxed containers.
Caution Do not exceed 4.5 lb ai/A per 12-month season. Do not graze or apply within 14 days of harvest.
Site of action Group 10: inhibits glutamine synthetase
Chemical family Phosphinic acid
isoxaben (Trellis SC)
Rate 0.495 to 1 lb ai/A (16 to 31 fl oz/A product)
Time Apply late summer to early fall, in early spring, or immediately after cultivation to debris-free soil surface. Activate with 0.5 inch water or shallow cultivation before weeds begin to emerge.
Remarks Identify weeds and adjust rates according to charts listed on label. Chemical stability remains adequate when left on soil surface for 21 days. Gallery is labeled for nonbearing sites, only.
Caution Do not apply to newly transplanted crops until the soil has settled and cracks disappear.
Site of action Group 21: inhibits cell wall synthesis Site B
Chemical family Benzamide
isoxaben + trifluralin (Snapshot 2.5TG)
Rate 5 lb ai/A (200 lb/A Snapshot 2.5TG)
Time Apply to weed- and debris-free soil that has settled with water and is free of cracks after transplanting.
Remarks Activate within 21 days using 0.5 inch of water or shallow cultivation before weeds begin to emerge.
Caution Follow label instructions for repeat treatments.
Site of action (isoxaben) Group 21: inhibits cell wall synthesis Site B; (trifluralin) Group 3: microtubule assembly inhibitor
Chemical family (isoxaben) benzamide; (trifluralin) dinitroaniline
napropamide (Devrinol)
Hazelnuts only
Rate 4 lb ai/A (8 lb 50 DF and XT)
Time Apply immediately after transplanting to firmed soil, before weeds emerge. Between November and February, activate with rain or overhead irrigation within 2 weeks; the remainder of the year, activate within 24 hours.
Remarks Where convenient, shallow mechanical incorporation appears to improve activation. Inhibits root growth.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Acetamide
oryzalin (Surflan)
Rate 2 to 6 lb ai/A (2 to 6 quarts/A Surflan AS)
Time Apply late fall to early spring to firmed soil; activate with rain or overhead irrigation or with shallow cultivation.
Remarks Not suggested for soils with more than 5% organic matter. Use higher rates for longer residual weed control. Avoid exposing transplant roots to treated soil. Inhibits cell division or mitosis, primarily in roots.
Caution Do not apply beneath newly planted trees until soil has settled and there are no cracks.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
oxyfluorfen (Goal 2XL)
Rate 1.25 to 2 lb ai/A (5 to 8 pints/A Goal 2XL or generic equivalent)
Remarks Controls broadleaf weeds pre- and postemergence depending on application rate and weed species.
Time Apply only to healthy and dormant trees. Direct spray toward the base of trees, avoiding direct plant contact. Acts as a contact herbicide, either directly on broadleaf weeds or at the soil surface as weeds emerge.
Site of action Group 14: inhibits protoporphyrinogen oxidase
Chemical family Diphenylether
pendimethalin (Prowl H2O)
Rate Prowl H2O: 1.9 to 6 lb ai/A (2 o 6.3 quarts/A), depending on crop and desired length of weed control. Prowl 3.3 EC: 1.98 o 3.96 lb ai/A (2.4 o 4.8 quarts/A)
Time Apply before weed emergence.
Remarks May be applied pretransplant incorporated, pretransplant surface, post-transplant surface incorporated, or posttransplant surface. Prowl is most effective if incorporated into soil with rain, irrigation, or shallow mechanical incorporation. Apply in single application or sequentially with an interval of 30 days or more. Do not exceed 4 quarts/A per year. Do not feed forage or graze livestock in treated orchards. Preharvest interval is 60 days.
Caution Do not apply over tops of trees with leaves, bud, or fruit. Apply directly to the ground beneath the trees or areas between rows.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
pronamide (Kerb 50W)
Pome and stone fruits only
Rate 1 to 4 lb ai/A (2 to 8 lb/A); rate depends on species present and soil texture.
Time Apply in fall, after fruit is harvested.
Remarks Seedling trees must be one year old, fall transplanted trees one year in the ground, and spring transplanted stock 6 months in the ground. Results are optimum if soil is below 55°F and application is followed by rain or irrigation. Requires moisture from overhead irrigation or rain to activate. Inhibits root growth. Poor control of weeds of the Asteraceae (Composite) family.
Caution A restricted-use herbicide. Do not exceed 8 lb/A, or one application per year.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Benzamide
pronamide (Kerb SC)
Nonbearing hazelnuts only (SLN No. OR-210004)
Rate 1 to 2 lb ai/A (2.5 to 5 pints/A); rate depends soil texture.
Time Apply in fall or winter. It can be applied to newly transplanted trees when soil is settled.
Remarks For preemergence or postemergence control of annual bluegrass, annual ryegrass, Italian ryegrass, perennial ryegrass, tall fescue, orchardgrass, volunteer grains and chickweed, and for preemergence control of susceptible broadleaf weeds. Results are optimum if soil is below 55°F and application is followed by rain or irrigation. Requires moisture from overhead irrigation or rain to activate. Inhibits root growth. Poor control of weeds of the Asteraceae (Composite) family. Pronamide can be applied as a single or split application
Caution A restricted-use herbicide. Do not exceed 2 lb/A, or two applications per year.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Benzamide
pyraflufen (Venue)
Rate 0.001 to 0.006 lb ai/A (0.7 to 4 fl oz product/A)
Remarks Apply as a directed application to actively growing weeds less than 4 inches high, or rosettes less than 3 inches in diameter. Use lower rate for small weeds and higher rate for larger weeds. Do not exceed three separate applications in-season (bloom to harvest). Do not exceed three separate applications out of season (postharvest to prebloom). Allow at least 30 days between applications. Venue may be applied up to three times in season, and three times postseason. Mixing Venue with another herbicide increases the weed spectrum and is highly recommended. It is recommended to add crop oil concentrate (COC), methylated seed oil (MSO), or organo-silicone for best weed control.
Caution This product is a contact, nonselective, broadleaf herbicide. Avoid contact with desirable foliage, green bark, or fruit.
Action in plant Inhibits protoporphyrinogen oxidase (PPO) that disrupts cell membranes.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Phenylpyrazole
sawdust
Hazelnuts and other crops
Time Apply 3- to 4-inch layer of mulch immediately after planting to suppress weed germination and conserve soil moisture.
Remarks Avoid mounding or thickly layering near tree trunk to reduce crown rot and injury from mice and other vertebrate pests. Lower rates of registered herbicides for new plantings sometimes can enhance weed control if applied before spreading mulch.
sethoxydim (Poast)
Rate 0.28 to 0.47 lb ai/A (1.5 to 2.5 pints/A product)
Time Identify susceptible grasses and apply at optimum growth stage listed on the label.
Remarks Apply 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 heat, 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 Preharvest intervals are: 14 days for apple and pear; 25 days for apricot, cherry (sweet and sour), nectarine, and peach; 15 days for nuts; and 1 year for plums and prunes. Maximum seasonal rates from 5 to 7.5 pints/A.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione
trifluralin (Treflan 4EC)
Rate 0.5 to 1 lb ai/A (1 to 2 pints/A Treflan 4EC)
Time Apply preplant and incorporate immediately by cross-disking or rototilling.
Remarks If crops are planted between trees, follow directions for both crops. Inhibits mitosis in roots and shoots. Preharvest interval is 60 days.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline