Thursday, May 12, 2016

Corn Replanting - Removing a Poor Stand

As farmers debate about destroying poor stands of corn and replanting, there are several herbicide guidelines to consider. There are several options to remove a poor stand, but those options depend on the type of hybrid currently growing in the field.
The following is an excerpt from AGR-6 2016 Weed Control Recommendations for Field Crops.

Emerged corn can be a problem in fields where corn must be replanted due to poor stands, flooding and other unforeseen weather conditions, or where volunteer corn plants emerge prior to planting. For conventional corn hybrids Roundup or other glyphosate products are often used to kill emerged corn prior to replanting. With the introduction of herbicide-tolerant crops such as “Roundup Ready” corn and “Liberty Link” corn hybrids, herbicide options are more limited for control of emerged corn prior to replanting. The table below indicates herbicide options depending on the genetic tolerance of the previous corn hybrid grown.

Herbicide treatments for control of existing stands of corn for replant situations.
Glyphosate Options
See page 22 for examples of glyphosate formulations. Consult label for specific rate of product and if a surfactant is needed and the type and rate of surfactant to include. Dry Ammonium Sulfate at 1 to 2% by weight (8.5 to 17 lb/100 gal) or an equivalent amount of AMS in a liquid formulation may improve glyphosate activity under certain conditions such as dry weather, or when mixed in hard water or with certain herbicides. Will not control hybrids with Roundup Ready corn technology.

Gramoxone Options
Gramoxone SL [2.0] (2.5 to 3.5 pt/A) + Linex 4L (0.67 to 1 pt/A) –OR– Atrazine 4L (0.5 to 1 qt/A)
+ Non-Ionic Surfactant (0.25% to 0.5% v/v)

Comments about Gramoxone: For control of volunteer corn up to 6 inches in height. Apply the higher rate of both herbicides for corn 7 to 12 inches in height. FIRESTORM, HELMQUAT and PARAZONE are similar paraquat products applied at 1.67 to 2.33 pt/A. With Atrazine maximum rate allowed may depend on previous applications. Apply with a non-ionic surfactant (NIS). Corn or grain sorghum may be planted at any time following application provided the combined maximum label rate has not been exceeded (consult label).

Select Max –OR– Intensity One (6 fl oz/A) + NIS (0.25% v/v) + AMS (2.5 to 4 lbs/A)

Comments about Clethodim: For control of an existing stand of Roundup Ready field corn or other volunteer corn plants prior to replanting to field corn. Apply on field corn up to 12 inches tall. Replant no sooner than 6 days after application. Apply with a non-ionic surfactant (NIS) plus Ammonium Sulfate (AMS). Do not use COC or MSO as a spray additive. Do not apply more than 6 oz/A per season.
GENERIC PRODUCTS: For other Clethodim products consult individual product for application rates.

For information about herbicide replant times, consult this section of AGR-6.

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