Weed Control Guide for Ohio Field Crops

Clearfield Corn: Postemergence Herbicides

Herbicide	Formulation	Product Rate Range
Lightning	70DF	1.28 oz

Tank-mix with: Buctril/Moxy, Banvel, Clarity, 2,4-D, Marksman, Distinct. atrazine, Shtogun, Laddok S-12, Buctril+atrazine.

• Lightning is a premix of imazethapyr (Pursuit) plus imazapyr for postemergence use on field corn hybrids that are resistant or tolerant to Pursuit and other imidazolinone herbicides. Hybrids should be labeled as "Clearfield" or with the designation "IR" or "IT" following the hybrid number.
• Mode of action: ALS inhibitor.
• Lightning is similar to Pursuit in weed control spectrum, but provides improved control of lambsquarters and longer residual activity compared to Pursuit. Control of common and giant ragweed is variable. Tank-mixes of Lightning with Distinct will improve control of ragweeds, lambsquarters, and perennial broadleaf weeds.
• OSU research has shown it can be difficult to achieve adequate season-long weed control with a single postemergence application of herbicides with limited residual activity. Applying Lightning with atrazine or following a reduced rate of a preplant or preemergence herbicide will result in more consistent control of longer duration. In fields with heavy grass pressure, use of a preemergence grass herbicide prior to postemergence use of Lightning is suggested.
• Apply before most annual weeds exceed 3 inches in height. Cocklebur, pigweed, shattercane, and seedling johnsongrass can be controlled up to 8 inches tall. For control or suppression of Jerusalem artichoke, apply when plants are 6 to 10 inches tall.
• Apply with nonionic surfactant (1 quart/100 gallons spray) plus nitrogen fertilizer solution (1 to 2 quarts/acre) or ammonium sulfate (2.5 lbs/A). Control of drought-stressed weeds will be maximized when the higher rates of fertilizer are used.
• Apply broadcast to corn up to 20 inches tall or the V6 stage, and as a directed spray until 45 days before harvest. Broadcast applications of Lightning when corn is more than 20 inches tall or past the V6 stage can result in poor kernel set and reduced yield. When tank-mixing Lightning with other herbicides, always follow the more restrictive label with regard to spray additives, maximum crop size, and other precautions.
• Control may be reduced when weeds are growing slowly under cold or dry conditions. If possible, wait for rain and resumption of active weed growth before applying Lightning. If air temperatures reach or stay below 50 degrees F for 10 or more hours, delay application for 48 hours from the time temperatures increase above 50 degrees F.
• Counter 20CR and Thimet may be applied only in a band where Lightning will be applied postemergence.
• Crop rotation restrictions: wheat, rye - 4 months after application; field and seed corn - 8 1/2 months; soybeans - 9 months; alfalfa, tobacco - 9 1/2 months; oats, popcorn, sweet corn - 18 months; most other crops - 40 months plus successful field bioassay. Inbred corn lines may vary in tolerance to Pursuit. Contact the inbred seed supplier for recommendations and information on tolerance before planting.

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