clethodim (Select Max and several trade names)
Rate 0.068 to 0.121 lb ai/A (9 to 16 oz/Ac)
Time Apply to actively growing grasses, including annual bluegrass, at growth stage listed on label, using 0.25% nonionic surfactant.
Remarks Carefully read label about adjuvants, effects of rain within 1 hr, application of other pesticides, and cultivation. Intensity and Intensity One have Special Local Needs (SLN) labels: WA-180004 and WA-180005, for chemigation application. Vaquero has a SLN label in Oregon for chemigation application: OR-190014.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione
clopyralid (Stinger)
Rate 0.124 to 0.188 lb ai/A (0.33 to 0.5 pint/A product)
Time Apply only when cranberries are not actively growing. In new plantings, this begins when cranberry vines go dormant in late fall and ends with early bud break.
Remarks Newly growing vines are very sensitive to Stinger. Identify susceptible weed species (legume and composite families), and apply postemergence when weed canopy becomes visible. Do not add surfactant or crop oil. SLN labels: WA-030006 and OR-030009.
Site of action Group 4: synthetic auxin
Chemical family Pyridine
mesotrione (Callisto and several trade names)
Rate 0.125 to 0.25 lb ai/A (4 to 8 oz/A product)
Time Apply only after bud break 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 27: inhibits 4-hydroxyphenylpyruvatedioxygenase (4-HPPD)
Chemical family Triketone
napropamide (Devrinol DF-XT, 2XT)
Rate 3 lb ai/A (6 lb/A Devrinol DF-XT)
Time Apply to weed-free soil surface after planting.
Remarks Requires irrigation or rain to activate. Results are best when applied just before weed seeds germinate. Devrinol may be applied through the sprinkler irrigation systems. Do not apply more than 3 lb ai/A per year.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Acetamide
norflurazon (Evital 5G)
Rate Up to 4 lb ai/A (80 lb/A product)
Time Apply after newly planted vines have rooted, but preferably in late winter or early spring, before weed growth begins.
Remarks 1 to 1.5 lb ai/A have performed adequately on new beds with low organic matter and high sand; 2.5 lb ai/A are required for new beds with high organic content.
Caution Do not exceed 4 lb ai/A total on new beds in 1 year. Hybrid varieties such as 'Stevens' and 'Pilgrim' are more prone to injury than 'McFarlin.' Injury is likely in areas where water puddles. Avoid use in consecutive years if crop phytotoxicity was noted in year one. Use lower rates and alternate with other herbicides as soon as labels permit. Only one application allowed per year.
Site of action Group 12: bleaching; inhibits carotenoid biosynthesis
Chemical family Pyridazinone
sethoxydim (Poast and several trade names)
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.
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) inhibitor
Chemical family Cyclohexanedione