Established Plantings-Postemergence Contact and Translocated Herbicides

clethodim (Select Max, Arrow)

Nonbearing fruit and nut trees except nectarines, plums, and chestnuts

Rate 0.068 to 0.121 lb ai/A (9 to 16 oz/A Select Max); 0.094 to 0.125 lb ai/A (6 to 8 oz/A Arrow)

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 0.5 lb ai/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

clopyralid (Stinger)

Stone fruits, apples

Rate 0.094 to 0.25 lb ae/A (0.25 to 0.66 pint/A Stinger)

Time Make 1 to 4 broadcast applications to Canada thistles that have emerged, but to rosettes before bud stage and at least 30 days before harvest.

Remarks Including apples (supplemental label) and stone fruits (apricots, Chickasaw plums, Damson plums, fresh prunes, Japanese plums, nectarines, peaches, plums, plumcots, sweet cherries, and sour cherries). Postemergence control of clover, dandelion, horseweed, nightshade (black and hairy), annual sowthistle, Canada thistle, musk thistle, and vetch. Do not exceed a total of 0.66 pint/A product per year. Apply in 10 gal/A of water or more.

Caution Preharvest interval is 30 days.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

flazasulfuron (Mission)

Rate 0.033 to 0.045 lb ai/A (2.14 to 2.85 oz/A)

Time Pre- and postemergent to broadleaf and grass weeds up to 4 inches tall, and before grasses tiller.

Remarks Apply as a directed spray to the soil beneath the trees to prevent injury to the foliage and bark. Apply only to trees 3 years old or older. Protective sleeves are required for third year trees. Use an adjuvant for postemergent applications. Must be activated with rainfall or irrigation of 0.25 to 0.5 inch for preemergence control; preemergence efficacy will be best if applied to bare soil. Do not disturb the soil after activation. If weeds are present, tank mix glyphosate or glufosinate to improve burndown and broaden weed control spectrum. Controls many grasses and broadleaf weeds, including annual ryegrass, roughstalk bluegrass, common mallow, clover, and willowherb. Reentry interval is 12 hr.

Caution Do not apply more than two applications at 2.85 oz/A per year. Preharvest interval is 130 days. Minimum retreatment interval (RTI) is 3 months. A 25-foot buffer must be maintained between the point of direct application and the closest downwind edge of sensitive terrestrial habitats (forested areas, riparian areas), freshwater habitats (lakes, rivers, sloughs), and estuarine/marine habitats.

Site of action Group 2

Chemical family Sulfonylurea

fluazifop-p-butyl (Fusilade DX)

Nonbearing in hazelnuts, walnuts, apples and pears; bearing in stone fruit

Rate 0.25 to 0.375 lb ai/A (16 to 24 oz/A Fusilade DX). Refer to specific grassy weeds listed on label.

Time Apply to actively growing grasses or within 7 days after irrigation as a directed spray with 1% crop oil or 0.25% nonionic surfactant.

Remarks Identify grasses and adjust rates depending on susceptibility and stage of weed growth as label instructs. Results often are erratic on grasses stressed from lack of vigor, high temperature, low fertility, or drought. More mature grasses and quackgrass can be controlled but may require two applications. Annual bluegrass and all fine fescues resist treatment. Inhibits fatty acid production, cell membranes, and new growth.

Caution Do not exceed 4.5 pints/A total per season. Preharvest interval is 14 days. Grazing is prohibited.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Aryloxyphenoxy propionate

glyphosate (numerous product names)

Rate Spray: read label carefully for crops listed and geographic location.

Time Apply to actively growing weeds.

Remarks Select application equipment to prevent crop injury, by directing spray or by using selective applicators. Adjust concentration depending on equipment, or consult label about rate and time of application, especially for perennial weeds. Avoid treating root suckers in late summer when spraying wild blackberries or other weeds. Additional surfactant or ammonium sulfate according to label instructions may improve control of slightly stressed weeds. Inhibits production of three amino acids and protein synthesis.

Caution Do not treat pear root suckers. Do not spray foliage or green bark. Preharvest interval is at least 14 days. If repeat applications are necessary, do not exceed a total of 10.6 lb ai/A per year. Grazing is prohibited. Repeated glyphosate applications have created resistant biotypes of ryegrass in Oregon. To avoid weed resistance, rotate and mix weed control practices.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

glyphosate (several products)

Rate Wiper: use 33% solution

Remarks Apply 1 gal product with 2 gal water and wipe weeds; avoid contact with desirable vegetation. In severe infestations, reduce equipment ground speed or apply in two directions to ensure wiper contact. See remarks above.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

glufosinate ammonium (Rely 280)

Rate 0.88 to 1.5 lb ai/A (3 to 5.1 pints/A Rely)

Time Apply to actively growing weeds as a directed spray or spot treatment according to stage of weed growth.

Remarks Avoid drift to or treatment of desirable foliage or green bark during establishment year. Only trunks with callused, mature brown bark should be sprayed.

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

halosulfuron (Sandea)

Apples and nut crops only

Rate Apples: 0.035 to 0.094 lb ai/A (0.75 to 2 oz/A); Nut crops: 0.031 to 0.063 lb ai/A (2/3 to 1 1/3 oz/A)

Time Apply in spring when nutsedge is not drought stressed.

Remarks Maximize the interval between application and irrigation. Trees must be established at least 12 months. Apply as a directed application at the base of the trees. Sandea also has soil residual activity and controls several broadleaf species, in addition to suppression of yellow nutsedge. For nutsedge control, apply Sandea as a single application when nutsedge is fully emerged (early to midsummer). Alternatively, two applications can be made. Apply the first application to the initial nutsedge flush when it has reached the 3- to 5-leaf stage. If a second treatment is needed, apply Sandea later in the season directed to secondary nutsedge emergence. Expect poor control if nutsedge has exceeded 12 inches in height.

Caution Take extreme care to avoid applying to stems, leaves, roots, or green bark of trees. Avoid spray drift onto adjacent crops. Clean spray tank carefully.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Sulfonylurea

mesotrione (Broadworks)

Tree nut crops, nectarine and plum only

Rate Stone fruits and tree nut crops: 0.94 to 0.188 lb ai/A (3 to 6 fl oz/A)

Time For preemergence control, apply in fall or spring before germination of weed seed. Rainfall or irrigation 0.25 to 1 inches is required for activation. For postemergence control, ensure good coverage using a minimum of 20 gal in dense foliage. Best control is obtained if postemergence applications are made before weeds reach 5 inches in height, or before germination of seed for preemergence control.

Remarks Broadworks can only be applied in stone fruit and nut trees that have been established for a minimum of 12 months. Maximum rate is 12 fl oz/A per season or 3 applications in 12 month period. Do not exceed 0.188 lb ai/A (6 fl. oz/A product) for the first application. Allow at least 5 months between applications of Broadworks at 6 fl oz/A and at least 6 weeks between applications of 6 fl oz/A and subsequent applications of 3 fl oz/A. Pre-harvest interval is 30 days. Do not use on soils with greater than 20% gravel.

Caution To avoid crop injury, apply the spray to the grove or orchard floor and to the weeds, avoiding contact with crop foliage, stems or fruit. Contact of Broadworks with the crop may result in bleaching injury that is typically temporary. Use trunk guards to protect plants until adequate bark has developed.

Site of action Group 27: inhibitor of p-hydroxyphenyl pyruvate dioxygenase (HPPD)

Chemical family Triketone

oxyfluorfen (Goal 2XL)

Rate 1.25 to 2 lb ai/A (5 to 8 pints/A Goal 2XL)

Time Apply only to healthy trees. Direct spray toward tree base, avoiding direct plant contact. Acts as contact, either directly on broadleaf weeds or at soil surface as weeds emerge. Weeds must be small for postemergence control.

Remarks Controls broadleaf weeds pre- and postemergence depending on application rate and weed species.

Site of action Group 14: inhibits protoporphyrinogen oxidase

Chemical family Diphenylether

paraquat (Gramoxone SL 2.0, Firestorm)

Rate 0.625 to 1 lb cation/A (2.5 to 4 pints/A Gramoxone, 1.7 to 2.7 pints/A Firestorm)

Time Apply as a directed spray toward tree base; ensure complete wetting when weeds are small.

Remarks Add a nonionic surfactant or crop oil concentrate as label specifies; take care to avoid anionic formulations that react in the tank to form insoluble precipitates. Acts on contact; absorbs energy produced by photosynthesis, forming peroxides that disrupt living cells.

Caution A restricted-use herbicide. Do not ingest or inhale spray mist. Wear protective shields, respirators, and clothing. Do not let spray contact foliage, fruit, or young tree trunks. Do not graze treated areas.

Site of action Group 22: photosystem I electron diversion

Chemical family Bipyridilium

rimsulfuron (Matrix FNV)

Rate 0.063 lb ai/A (4 oz/A Matrix FNV per year)

Time Applied before or shortly after weed emergence, fall or spring depending on weed species targeted.

Remarks Supplemental label. Apply as a broadcast or banded application, avoiding foliage, fruit, and desirable suckers. One application per year unless banding, then two applications area allowed with a maximum application of 4 oz/A on a broadcast basis. Apply when rain and cool temperatures are expected. Results are best if soil is moist at time of application and with 0.5 inch of rain or irrigation within 2 weeks after application. Postemergence control is best if weeds are small and an adjuvant is used. Preemergence and postemergence control of a number of grasses and summer annuals including puncturevine, dandelion, mallow, and quackgrass; postemergence partial suppression of yellow nutsedge. Preharvest interval is 7 days for pome fruit and 14 days for stone fruit and nuts.

Caution Trees must be established for 12 months. Avoid spray drift onto adjacent crops. Clean spray tank carefully. Minimize contact with fruit or foliage.

Site of action Group 2: acetolactate synthase (ALS) inhibitor

Chemical family Sulfonylurea

sethoxydim (Poast)

Rate 0.28 to 0.47 lb ai/A (1.5 to 2.5 pints/A Poast)

Time Apply at optimum growth stage listed on the 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; quackgrass can be suppressed. Maximum seasonal rates of 5 to 7.5 pints/A. Inhibits fatty acid production, cell membranes, and new growth.

Caution Preharvest interval is 14 days for apples and pears; 25 days for apricots, cherries (sweet and sour), nectarines, and peaches; 15 days for nuts.

Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor

Chemical family Cyclohexanedione