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Title: Evaluation of Potassium-Based Ripeners as an Alternative to Polado/Tropical Storm Isidore and Hurricane Lilli's Effects on Polado-Treated Cane/The Effects of 2,4-D on Polado Activity

Author
item VIATOR, BLAINE - CALVIN VIATOR & ASSOC
item VIATOR, CALVIN - CALVIN VIATOR & ASSOC
item Richard Jr, Edward
item JACKSON, WINDELL - ASCL OF THE USA
item WAGUESPACK, HERMAN - ASCL OF THE USA
item VIATOR, GEORGE - REBEL V FARMS
item VIATOR, JACK - REBEL V FARMS

Submitted to: Sugar Bulletin
Publication Type: Popular Publication
Publication Acceptance Date: 3/5/2003
Publication Date: 3/5/2003
Citation: Viator, B., Viator, C., Richard Jr, E.P., Jackson, W., Waguespack, H., Viator, G., Viator, J. 2003. Evaluation of Potassium-Based Ripeners as an Alternative to Polado/Tropical Storm Isidore and Hurricane Lilli's Effects on Polado-Treated Cane/The Effects of 2,4-D on Polado Activity. Sugar Bulletin. 81(6):22-28.

Interpretive Summary: To be competitive with other cane sugar producing regions of the U.S. and the world that have longer growing seasons, the Louisiana sugarcane industry relies on the use of late-season foliar applications of Polado® whose active ingredient is the herbicide glyphosate. Increases in sugar yield following a late-season application of glyphosate often comes at the expense of reduced cane yields in the treated crop as well as the remaining ratoon crops of the crop cycle. Large plot field studies were conducted to evaluate the (1) foliar application of the fertilizer potassium nitrate as an alternative to glyphosate in enhancing both cane and sugar yields at harvest and (2) potential for reduced ripener activity when 2,4-D was applied in mixture with glyphosate to provide some control of morninglory weeds. As expected, a ripener application of glyphosate reduced gross cane yields slightly (3%) but increased sugar yields significantly (912 lbs./acre). Inclusion of 2,4-D in tank mixture did not affect the ability of the glyphosate to enhance sugar yields. Foliar applications of potassium nitrate, increased gross cane yields slightly but had no influence on sucrose accumulation. As a result, sugar yields were lower than the standard glyphosate ripener treatment. The Louisiana sugarcane industry¿s continued dependence on glyphosate as a ripener, may also hamper attempts to incorporate glyphosate-tolerant sugarcane in the growers arsenal of weed management tools. Since gross cane yields were higher and their was a slight trend to increasing sugar yields at the designated harvest time, additional studies with potassium nitrate evaluating longer treatment to harvest intervals may be warranted.

Technical Abstract: Large scale field studies were conducted in Louisiana during the 2002 growing season to evaluate the: (1)use of potassium nitrate as an alternative to low rates of the herbicide glyphosate (Polado® at 6 oz. product/acre) in sugarcane to enhance sucrose accumulation (ripen) and (2) possible antagonism of glyphosate¿s ability to ripen sugarcane when 2,4-D at 1.0 qt/acre was applied in mixture. At 49 days after treatment, gross cane yields were reduced 3% by standard ripener rates of glyphosate, but sugar yields were increased by 912 lbs./acre. Inclusion of 2,4-D did not affect sucrose accumulation associated with the glyphosate ripener treatment or sugar yields at harvest. At the standard 49-day treatment to harvest interval, gross cane yields were higher than the non-treated check and 10 to 15% higher than the standard glyphosate ripener treatment where potassium nitrate at 6.6 lbs/acre was applied. However, potassium nitrate did not increase sugar yield to the level obtained with glyphosate. Hence, per acre sugar yields were significantly lower than the standard glyphosate ripener treatment. During the 2002 harvest season, the Louisiana sugarcane industry was hit with Tropical Storm Isidore and Hurricane Lilli. Observations made after the storms suggest that glyphosate had caused an increase in stalk brittleness as many of the tops in the glyphosate-treated plots were broken.