clethodim (Select 2EC or others)
Rate 0.094 to 0.125 lb ai/A (6 to 8 fl oz/A Select), depending on whether annual or perennial species dominate.
Time Apply to actively growing grass weeds, including annual bluegrass, at growth stages on label.
Remarks Read label carefully for adjuvant instructions, typically 1% crop oil concentrate without nitrogen solution. Note effects of rain within 1 hour, application of other pesticides, and cultivation.
Caution Consult labels for maximum rates per application and season. Preharvest interval is 14 days for leafy brassica greens, 30 days for head or stem brassica vegetables.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione
clopyralid (Spur)
Except rutabaga, radish and horseradish
Rate Apply 0.093 to 0.188 lb ae/A (0.25 to 0.5 pints/A) with ground equipment in 10 to 40 gal/A total spray volume.
Time Apply to wild buckwheat at the one- to three-leaf stage of growth, before vining begins. Apply to common ragweed and sweet clover from weed emergence up to the five-leaf stage of growth. To suppress sowthistle, apply from rosette up to bud stage.
Remarks Controls wild buckwheat, sweet clover, prickly lettuce, common ragweed, and galinsoga. Suppresses sowthistle, groundsel and nightshade. Preharvest interval is 30 days. Make one broadcast application per crop per year.
Caution Experience is lacking with this product on many of these crops in the PNW. Stinger is excluded from use in the PNW as of this revision date.
Site of action Group 4: synthetic auxin
Chemical family 6-Chloropicolinate
pendimethalin (Prowl H2O, AquaPen 3.8, Satellite Hydrocap)
Rate 0.475 to 1 lb ai/A (1 to 2.1 pints/A) depending on soil type.
Time Postemergence directed or broadcast foliar, depending on label.
Remarks Preemergent weed control; will not control emerged weeds. Labels differ slightly on allowed applications depending on crop group. In general, labeled uses are more restrictive for head and stem brassicas than leafy green brassicas. Directing application of pendimethalin between transplanted or direct seeded rows at the 2 to 5 leaf stage will extend weed control with little risk of injury. Broadcast postemergence applications are allowed on brassica leafy green crops at the 4 to 5 leaf stage on the Hydrocap label.
Caution Do not apply within 21 days of harvest and do not apply more than 1.05 quarts/year. Do not apply pre-plant or pre-emergence or severe injury will occur.
Site of action Group 3: microtubule assembly inhibitor
Chemical family Dinitroaniline
S-metolachlor (Dual Magnum)
Rate 0.63 to 1.27 lb ai/A (0.67 to 1.33 pints/A)
Time Broadcast postemergence application within 48 hr after transplanting. Direct-seeded crops should have more than 1 true leaf by time of application
Remarks Special local needs indemnified label for various brassicas (OR-070006). SLN label includes mustard greens, broccoli, cabbage, collards, kale, rape greens, Brussels sprouts, cauliflower in OR only.
Caution In general, the risk of crop injury from the use of Dual Magnum is lower for post-transplant than pre-transplant applications, and the risk of crop injury is lower with post-directed than from over-the-top post-transplanting applications. Applying Dual Magnum before bed formation may result in crop injury due to the incorporation and/or concentration of Dual Magnum directly near the transplanted crop's root system. Napa cabbage and bok choi are less tolerant to Dual Magnum. Direct-seeded crops also have higher risk of crop injury. Muck soils require higher labeled rates. The addition of another registered herbicide, especially Goal (oxyfluorfen) will increase risk of crop injury from postemergence applications. Greater injury may occur if oxyfluorfen was applied before transplanting. Preharvest interval is 60 days.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Chloroacetamide
sethoxydim (Poast)
Rate 0.19 to 0.28 lb ai/A (1 to 1.5 pints/A)
Time Apply at optimum growth stage listed on the label.
Remarks Identify susceptible grasses and add 2 pints/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 development, and new growth.
Caution Preharvest interval is 14 days for mustard greens, 30 days for all other crops. Do not exceed 1.5 pints/A per application or 3 pints/A per season.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione