Established Beds

2,4-D low-volatile ester (Riverdale 2,4-D Granules)

Rate 2 to 4 lb ae/a (10 to 20 lb/a product)

Time Apply in early spring, while cranberries are dormant and leaves are completely dry.

Remarks Use higher rates as spot treatments on certain perennial weeds only; use lower rates in combination with other herbicides. Early winter applications may be effective against several broadleaf biennial species. Mimics natural plant hormones.

Site of action Group 4: synthetic auxin

Chemical family Phenoxy acetic acid

chlorimuron (Curio)

Rate 0.008 to 0.016 lb ai/a (Washington: 0.5 to 1 oz/a, Oregon: 0.5 oz/a product)

Time Apply any time after March 1 but no later than 60 days before harvest. Use lower rate (0.5 oz/a) from the hook stage of development to bud set.

Remarks Requires waiver of liability signature prior to use. Controls creeping buttercup and several other perennial weeds. Optimal control of creeping buttercup can be achieved from a March to April timing. Requires the use of a spray adjuvant. Special Local Needs labels: WA-100004 and OR-120001.

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

Chemical family sulfonylurea

clethodim (Intensity, Intensity One, and other products and formulations)

Rate 0.094 to 0.125 lb ai/a (6 to 8 oz/a of 2EC formulation)

Time Apply to actively growing grasses, including annual bluegrass, at growth stage listed on label using 0.5% to 1% nonphytotoxic crop oil or 0.25% nonionic surfactant. Preharvest interval is 30 days.

Remarks On label, carefully read about adjuvants, effects of rain within 1 hour, application of other pesticides, and cultivation. 'Intensity' and 'Intensity One' have Special Local Needs labels: WA-180004 and WA-180005, for chemigation application.

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

Chemical family Cyclohexanedione

clopyralid (Stinger)

Rate 0.09 to 0.25 lb ai/a (0.25 to 0.66 pints/a product)

Time Apply only when cranberries are not actively growing. This begins when cranberry vines go dormant in late fall and ends with budbreak. The second application period is after fruit set, up to 60 days before harvest.

Remarks Vines growing under the weed canopy may be sensitive to Stinger. Identify susceptible weed species (legume and composite families), and apply postemergence when weed canopy becomes visible. Results are best when applied before weeds mature. Do not exceed 0.67 pint/a per season. Do not add surfactant or crop oil. Special local needs labels WA-030006 and OR-030009.

Site of action Group 4: synthetic auxin

Chemical family Pyridine

dichlobenil (Casoron 4G)

Rate 1.2 to 4 lb ai/a (30 to 100 lb/a product)

Time Apply from midwinter to early spring, before bud break.

Remarks Results on sandy soils usually are best with split applications in midwinter to early spring. Allow 3 to 6 weeks between treatments. Do not exceed 4 lb ai/a (100 lb/a) total per year. Irrigation or rain should follow applications to minimize vaporization and loss of chemical. Use higher rates only on very weedy beds and organic soils. Plants will temporarily redden after spring applications.

Caution Do not apply at or beyond popcorn stage, or on newly sanded or new beds. Injury may occur where applications overlap or where water stands in low wet areas. Use lower rates (1.2 to 2.3 lb ai/a) on soils low in organic matter. Continued use at medium to high rates on sandier soils will result in a gradual but significant decline in production and plant health. Sanding is recommended to remediate the negative impacts of long term use of dichlobenil.

Site of action Group 20: inhibits cell wall synthesis Site A

Chemical family Nitrile

mesotrione (Callisto)

Rate 0.33 to 0.67 lb ai/a (4 to 8 oz/a product)

Time Apply only after budbreak but less than 45 days before flooding.

Remarks Use with a nonionic surfactant at 0.25% v/v or crop oil at 1% v/v as recommended by the label. Callisto may be applied in cranberries at a rate up to 8 fl oz/a. Do not exceed 16 fl oz/a or two applications per year. Allow at least 14 days between treatments. Callisto may be applied through irrigation systems (chemigation) including center pivot or solid set.

Caution Avoid using crop oils that injure cranberry vines.

Site of action Group 28: inhibits 4-hydroxyphenylpyruvatedioxygenase (4-HPPD)

Chemical family Triketone

napropamide (Devrinol DF-XT, 2-XT)

Rate Sand beds: 4 to 6 lb ai/a (8 to 12 lb/a of DF 2-XT formulation); Peat beds: 6 to 9 lb ai/a (12 to 18 lb/a of DF-XT formulation)

Time Apply before weeds begin to germinate and before spring growth begins, in mid-February to mid-March.

Remarks Requires ample rain or irrigation to activate. On 1-year-old beds, use lower rates. Crop may be injured at high rates. Control may lessen with repeated use. Inhibits root and shoot growth. Devrinol may be applied through the sprinkler irrigation systems.

Caution Do not apply after buds begin to swell.

Site of action Group 15: inhibits very long chain fatty acid synthesis

Chemical family Acetamide

norflurazon (Evital 5G)

Rate 1 to 6 lb ai/a (20 to 100 lb/a product)

Time Apply midwinter to early spring, before new vine growth begins.

Remarks Use lower rates not exceeding 3 lb ai/a on: sandy soils low in organic matter; on sensitive hybrid varieties such as "Stevens," "Pilgrim," or "Crimson Queen"; on young plants; or on beds with weak vines. Higher rates are required on older beds with higher organic content. Some growers and researchers report reduced crop yields when the product is applied in consecutive years, especially with new hybrids. Injury may occur if applications overlap, or if water stands in low, wet areas. Use lower rates and alternate with other herbicides to reduce possibility of injury.

Site of action Group 12: bleaching; inhibits carotenoid biosynthesis

Chemical family Pyridazinone

quinclorac (Quinstar 4L)

Rate Up to 0.25 ai/a (8.4 oz/a product)

Time Quinstar 4L is most effective on actively growing cranberry weeds listed on the label, when applied at the early postemergence stage of development.

Remarks Apply as a foliar application using a crop oil concentrate at a rate of 2 pints/a. A second application may be made at least 30 days after the first application. Do not exceed more than two applications per year. Quinstar 4L may also be applied with chemigation. Prior to application, consult your handler for MRL restrictions on export fruit.

Site of action Group 4: synthetic auxin

Chemical family Quinoline carboxylic acid

sethoxydim (Poast)

Rate Spray: 0.28 to 0.47 lb ai/a (1.5 to 2.5 pints/a product). Spot treat: 2 oz or 4 Tbsp/gal water + 2.5 oz or 4 Tbsp crop oil concentrate

Time Apply at optimum growth stage listed on the label. Preharvest interval is 60 days.

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. Inhibits fatty acid production, cell membranes, and new growth.

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

Chemical family Cyclohexanedione