clomazone (Command 3ME)
Rate 0.15 to 0.25 lb ai/a (0.4 to 0.67 pints/a Command 3E) Use lower rate on coarse soils and the higher rate on fine soils.
Time After planting and before weed emergence.
Remarks A microencapsulated (ME) formulation is registered for use, but experience in snap beans is lacking in the Pacific Northwest. Therefore, experiment on a small scale before treating whole fields. This formulation is designed to minimize drift and injury to adjacent fields and sites.
Rotational cropping precautions: all crops can be planted at 16 months after application. Other restrictions depend on crop, rate, region, and soil pH. Small grain cereals and corn may be sensitive to carryover residues in the fall and the spring, respectively. Cover crops may be planted anytime but stand reductions may occur in some areas. However, do not graze or harvest cover crops for food or feed planted less than 9 months after applications.
Caution Allow 300 ft between the application site and desirable crops. Do not apply upwind of sensitive crops such as berries and ornamentals.
Site of action Group 13: inhibits DOXP synthase
Chemical family Isoxazolidinone
Oregon only SLN OR-150018 For use only in the counties of Benton, Clackamas, Columbia, Lane, Linn, Marion, Multnomah, Polk, Washington And Yamhill
Rate 0.5 to 1 pint/a (0.125 to 0.25 lb ai/a Reflex) depending on soil type
Time Preplant surface and postplant surface.
Remarks Must be activated with rainfall or irrigation of 0.5 inch or more and before weed seeds germinate for best efficacy. Failure to activate the herbicide before snap bean seedlings emerge increases the risk of damage to the crop if there is a heavy downpour and soil is splashed onto leaves. Reflex effectiveness will be reduced if later cultural practices expose nontreated soil. Preharvest interval is 32 days. Controls pigweed, nightshade, and lambsquarters; suppression of nutsedge; good puncturevine control; poor grass control.
Caution Do not exceed 1 pint/a of Reflex per season. Do not apply to a field more than once every 2 years. Snap beans, squash, and potatoes can be planted immediately after application. Wheat, perennial ryegrass, and tall fescue can be planted 4 months after application; sweet corn 10 months after application. Bentgrass rotation interval is 12 months. Beets, brassica crops, and all other crops not listed on the label cannot be planted until 18 months after application. Do not apply after snap beans have emerged or injury may be serious. REI 24 hr.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Nitrophenylether
halosulfuron-methyl (Sandea, Stadia, Profine)
Rate 0.023 to 0.047 lb ai/a (0.5 to 1 oz/a Sandea)
Time Apply after planting but before soil cracks. Adjust rates, depending on soil texture and organic-matter content.
Remarks Do not exceed 2 oz/a herbicide per year.
Caution Crop growth may be stunted briefly after emerging. See label for rotation crops, interactions with soil-applied organophosphate insecticides that may increase crop injury, and other precautions. Application after beans have emerged will temporarily stunt growth and cause yellowing.
Site of action Group 2: acetolactate synthase (ALS) inhibitor
Chemical family Sulfonylurea
Supplemental label, Oregon only
Rate 0.125 to 0.19 lb ai/a (8 to 12 fl oz/a Cobra)
Time Apply within 48 hr after planting, followed by 0.25 to 0.5 inch rain or irrigation before beans crack soil and emerge.
Remarks Controls pigweed and nightshade but is weak on lambsquarters and does not control grasses and smartweed.
Caution Hard-driving rain at emergence may splash Cobra-treated soil onto snap beans, and this may damage emerging seedlings. In most cases, this crop response is temporary, and beans quickly outgrow it without negative effects to yield or quality. Severe crop response can be aggravated if beans are already under stress at emergence. Avoid field conditions that do not favor quick snap bean emergence, including soil temperatures below 60°F, planting depth below 1.5 inches, and using rollers after planting that compact and seal the soil surface. Flat, sealed soil surfaces increase water ponding and splashing of treated soil during thunderstorms, splashing Cobra-treated soil directly onto plant leaves. Avoid use of big guns that may increase splashing of treated soil onto bean leaves. Read groundwater advisory on label. Preharvest interval is 55 days.
Site of action Group 14: protoporphyrinogen oxidase (PPO) inhibitor
Chemical family Diphenylether
S-metolachlor (Dual Magnum or Cinch) or metolachlor (Me-Too-Lachlor or Parallel)
Rate 0.95 to 1.9 lb ai/a (1 to 2 pints/a S-metolachlor). See table above under Preplant Incorporated.
Time Apply preemergence after planting and activate with 0.5 inch overhead irrigation or rain.
Remarks May delay maturity and/or reduce yield if soil is cold and wet, or if heavy rains fall after planting. Controls many summer annual grasses, pigweed and other broadleaf weeds, but is weak on lambsquarters, mustard weeds and nightshade. Inhibits roots and shoot growths.
Caution May delay maturity and/or reduce yield if soil is cold and wet or if heavy rains fall after planting. Preharvest interval is 120 days for hay. Excess rainfall or irrigation will significantly impair weed control.
Site of action Group 15: inhibits very long chain fatty acid synthesis
Chemical family Chloroacetamide