NEW AND IMPROVED CULTURAL PRACTICES FOR SUSTAINABLE SUGARCANE PRODUCTION AND ENVIRONMENTAL PROTECTION
Location: Sugarcane Research Unit
Title: Early harvest affects ratooning ability in Louisiana
Submitted to: Sugar Journal
Publication Type: Trade Journal
Publication Acceptance Date: December 30, 2008
Publication Date: January 15, 2009
Citation: Viator, R.P., Dalley, C.D., Richard Jr, E.P. 2009. Early harvest affects ratooning ability in Louisiana. Sugar Journal. 71(8):12-14.
Similar to sugarcane industries around the world, economies of scale often lead to decreases in total number of manufacturing centers such as sugar mills. One of the consequences of mill closures has been an increase in the duration of the crushing season in Louisiana, which has historically been from mid-October to late-December. A series of experiments was conducted by scientists at the USDA-ARS Sugarcane Research Laboratory in Houma, LA to investigate the effects of early harvest on ratooning ability. An initial study was initiated with L 97-128 in 2004 to determine the effects of early harvest on ratooning ability. Treatments consisted of the three plant-cane harvest dates of October 1, November 1, and December 1, 2004. The first-ratoon sugar yields for the harvest dates of October 1, November 1, and December 1 were 7300, 8400, and 9400 kg/ha, respectively. The extent of the yield decrease was somewhat unexpected and prompted researchers to determine a way to mitigate this yield decline.
A second study was initiated in 2005 with the objective of determining varietal differences in ratooning ability after an early harvest. In this study, the number of varieties was increased to include L 97-128, and three other varieties that were being grown commercially in Louisiana, LCP 85-384, Ho 95-988, and HoCP 96-540. Treatments consisted of harvesting plant-cane on October 1 and December 1, 2005 and 2006. Averaged across all varieties, the early harvest of plant-cane reduced sugar yields of the first ratoon by 2000 kg/ha relative to the later harvest date which yielded 9700 kg/ha. When one compares the yields of the four varieties when harvested early the previous year, the sugar yields for L 97-128 were 600, 3000, and 3900 kg/ha greater than HoCP 96-540, LCP 85-384, and Ho 95-988, respectively. Yields of HoCP-540 were significantly higher than those of LCP 85-384 and Ho 95-988. Therefore, it appeared that L 97-128 was the best variety to plant for ratooning after an early harvest with HoCP 96-540 showing moderate ratooning ability after an early harvest.
A third experiment was initiated in 2005 and repeated in 2006 to determine the effects of two consecutive years of early harvesting (plant-cane plus first-ratoon) on yields of the second-ratoon crop. Plots of LCP 85-384, Ho 95-988, HoCP 96-540, and L 97-128 were harvested as plant-cane (2005 and 2006) and first-ratoon (2006 and 2007) on October 1 and December 1. Averaged across all varieties, the early harvest of both plant-cane and first-ratoon crops reduced sugar yields of the subsequent second-ratoon crop by 5300 kg/ha relative to the later harvest which yielded 10500 kg/ha. For the early harvest date, LCP 85-384, HoCP 96-540, and L 97-128 had significantly higher sugar yields (6100, 5600, and 6000 kg/ha) relative to Ho 95-988 (3600 kg/ha).
Despite these varietal differences, if one considers that the projected breakeven point for sugar production in Louisiana (based on LSU Ag Center’s Projected Sugarcane Production Costs for 2007) is 8200 kg/ha, consecutive years of early harvest, regardless of variety, produces yields that are not economically feasible. Moreover, several negative traits of LCP 85-384 (brown rust susceptibility and rapidly declining yields) and L 97-128 (rapid post-harvest freeze deterioration, erratic sugar yields, and high levels of smut infestation) have sharply curtailed the planting of these varieties. It is currently suggested that growers should not harvest cane early in consecutive seasons. Ongoing studies are screening newly released cultivars including L 99-226, L 99-233, HoCP 00-950, and L 02-283 for ratooning ability after early harvests.