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Title: EVALUATION OF POTASSIUM-BASED RIPENERS AS AN ALTERNATIVE TO GLYPHOSATE AND THE EFFECTS OF 2,4-D ON HERBICIDAL CANE RIPENING

Author
item VIATOR, BLAINE - CALVIN VIATOR & ASSOC
item VIATOR, CALVIN - CALVIN VIATOR & ASSOC.
item JACKSON, WINDELL - ASCL
item WAGUESPACK, HERMAN - ASCL
item Richard Jr, Edward

Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 5/20/2003
Publication Date: 6/20/2004
Citation: Viator, B.J., Viator, C., Jackson, W., Waguespack, H., Richard Jr, E.P. 2004. Evaluation of potassium-based ripeners as an alternative to glyphosate and the effects of 2,4-d on herbicidal cane ripening [abstract]. Journal of the American Society of Sugar Cane Technologists. 24:98.

Interpretive Summary:

Technical Abstract: Glyphosate (Polado®) is the only registered ripener for use in Louisiana. Past research has proven it to be effective as a cane ripener, but growers are restricted to a harvest window of 35 to 49 days after treatment (DAT). The delayed emergence of glyphosate-treated cane the following spring is an undesirable side affect of glyphosate. Recent research from Ecuador indicated foliar applied potassium nitrate increased sugar per ton of cane similar to glyphosate with no reduction in cane growth at 43 DAT. A second product, potassium carbonate (Kayphol®), has been sold in Louisiana as a non-herbicidal ripener. No studies have been conducted to evaluate the potential effectiveness of these products under Louisiana conditions. Additionally, situations occur where 2,4-D could be tank-mixed with glyphosate to provide cane ripening and morningglory control in one application. Much research in weed control has indicated that the addition of 2,4-D may antagonize the activity of glyphosate on certain plant species. Because there is no data available on the antagonistic potential of 2,4-D on glyphosate's ripening capabilities, this tank-mix is not recommended. Treatments were aerially applied at 5 GPA to second stubble LCP 85-384 at Rebel V Farms in New Iberia, LA on August 27, 2002. Each plot consisted of two 6-row swaths, was 2.1 acres in size, and was replicated four times in a randomized complete block design. The treatments applied were glyphosate @ 0.19 lbs ai/A (6 oz Polado 4L), glyphosate @ 0.19 lbs ai/A + 2,4-D @ 0.95 lbs ai/A (1 qt/A Hi Yield 2,4-D 3.8 L), potassium nitrate @ 6.60 lbs/A (46% K2O; 13.75% N), potassium carbonate @ 2.09 lbs K2O/A (2 qt/A Kayphol), and a nontreated check. Beginning 14 DAT, Brix measurements from twenty stalks in each plot were taken weekly until harvest. Stalk and leaf samples were collected for sucrose and tissue analysis at 21 and 49 DAT. Sugarcane was combine harvested 49 DAT with theoretical recoverable sugar (TRS) being determined at a commercial core lab. Treatments of glyphosate, glyphosate + 2,4-D, potassium carbonate, and potassium nitrate were also included in a small plot experiment conducted at the USDA-ARS Ardoyne Research Farm at Schriever, LA. Treatments were replicated four times in a randomized complete block design. The rates of these treatments and date of application were consistent with the large plot experiment. Treatments were applied using a CO2-pressurized backpack sprayer calibrated to deliver 10.5 gallons per acre. Hand-cut stalk samples cut from each plot were processed for sucrose analysis at 28, 35, and 42 DAT. Commercial core sample data and field measurements from the large plot experiment indicated a 34 lb/ton increase in TRS and a 912 lb/A increase in sugar yield for the glyphosate treatment compared to the nontreated check. Results from the tissue analysis of leaves in the canopy showed a significant increase in concentrations of magnesium and calcium levels at 21 DAT for glyphosate-treated cane versus the nontreated check. For the large plot experiment, percent Brix of the glyphosate-treated cane was consistently higher than potassium nitrate, potassium carbonate, and the nontreated cane throughout the monitoring period. The potassium nitrate and potassium carbonate treatments were not statistically higher than the nontreated in most weeks, with the exception of the final measurements at 49 DAT in which juice Brix of the potassium nitrate treatment was greater than the nontreated, but less than the glyphosate treatment. Analysis of the hand cleaned, twenty-stalk samples showed significantly higher TRS for potassium nitrate over the check at harvest; however, this was not detected in the commercial core samples. Potassium nitrate and potassium carbonate did not increase core sample TRS or sugar yield compared to the nontreated check.