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Only glyphosate products licensed and labeled for use with Roundup Ready (RR) hybrids may be used. Products having different formulations and different amounts (lb) of acid equivalent (ae) and active ingredient (ai) are listed below.
POST. Apply to Roundup Ready (RR) corn from emergence through the V8 stage (8 leaves with collars) or until corn height reaches 30 inches, whichever comes first. Avoid drift. Extreme care must be taken to prevent injury to desirable and non-target plants and crops that do not contain genetic tolerance to glyphosate. Follow cleanup procedures to avoid crop damage from equipment contamination.
Carrier is 5-20 gpa for ground and 3-15 gpa for air. Add 8.5-17 lb AMS/100 gal. Allow at least 50 days between application and harvest of corn forage and 7 days between application and harvest of corn grain. Allow a minimum of 10 days between in-crop applications.
Sequential in-crop application of glyphosate can be applied according to the maximum rates shown below.
PRE. Glyphosate products list several preemergence tank-mixes. Labeling for many preemergence residual or postemergence burndown products used prior to crop emergence includes tank-mixes with glyphosate.
POST. Glyphosate products and potential tank-mix partners include labeling for several postemergence tank-mixes. Product labels vary considerably. Labeling may be on the glyphosate product or the tank-mix partner. Tank-mixes listed include herbicides that provide preemergence residual or postemerge activity in tank-mixes with glyphosate, Clarity, Degree products, dicamba, Distinct, Dual, Fultime, Guardsman Max, Harness products, Hornet, Keystone products, Lumax, Marksman, Micro-Tech, Outlook, Permit, Priority, Resource, Stinger, Surpass products, TopNotch, and 2,4-D. Consult your product label or supplemental labels that may apply.
ROUNDUP READY 2 (RR2) CORN Use glyphosate products specifically registered for use on RR 2 corn. Product examples include: 3 ae: Roundup Original, Roundup Original II, GlyStar Plus, Cornerstone Plus. 3.75 ae: Roundup UltraMax. 4.5 ae: Roundup UltraMax II, Roundup Original Max, and Roundup WeatherMax.
POST. Designated rates are listed below. The “event” used in developing these hybrids provides a resistance level that allows higher glyphosate rates if required. Apply from emergence through 8 leaf collar stage or 30 inches. Drop nozzles suggested when corn height is 24-30 inches. Drop nozzles required when corn is 30-48 inches. Do not make a preharvest application if a combined total of 1.5 lb ae has previously been applied over the top or with drop nozzles. Do not harvest for grain or forage for 50 days after in-crop application. Allow 7 days before harvest or feeding corn fodder or grain with preharvest application.
PRE and POST. Specific tank-mixes listed on the glyphosate products labeled for Roundup Ready 2 hybrids include Degree, Degree Xtra, Distinct, Harness, Harness Xtra, Bullet, Micro-Tech, Permit, and atrazine. Follow label interpretations for other glyphosate or potential tank-mix partners.
SEQUENTIAL for ROUNDUP READY and ROUNDUP READY 2
PRE and POST. Several preemergence herbicides may be used at reduced rates to be followed by glyphosate postemergence.
Rates of 60% of full normal rate have been used in SDSU tests. These programs include herbicides for early residual control.
Suggested programs for fields with moderate or heavy weed pressure.
GLYPHOSATE TOLERANT (GT) CORN
Some hybrids are designated as Glyphosate Tolerant (GT), containing technology that provides in-plant tolerance to glyphosatebased herbicides. The following glyphosate products have additional labeling that includes Glyphosate Tolerant (GT) hybrids: 3 ae:
Touchdown IQ. 4.17 ae: Touchdown Total. 5 ae: Touchdown Hi-Tech.
Refer to interpretation of product labels for other glyphosate products or potential tank-mix partners.
South Dakota 2013 Crop Protection Guide – Corn 41