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Keywords: glyphosate, growth regulators, ratoons, ripeners, sugarcane. La aplicacion de glifosato a fin de ternporada como madurador; junto con la retencion ...
abstract Different sources of plant stress, when present together, can have compounded effects on cane growth and yield. The objectives of this experiment were to determine: 1) if late-season (Nov. 1) glyphosate ripener application increases sucrose yield in the four common commercial sugarcane cultivars grown in Louisiana, USA 2) cultivar differences in susceptibility to injury from residual glyphosate in successive ratoon crops, and 3) if the stress of residual glyphosate on the subsequent ratoon crop is compounded by the presence of post-harvest residue. Glyphosate was applied on Nov. 1 (0.21 kg at ha') to the flrst-ratoon crop. Two weeks after the first ratoon was harvested, the blanket of crop residue was either allowed to remain or completely removed by burning. Regardless of variety, late-season ripener application offered no increase in sucrose yield in first ratoon, and residual effects of glyphosate in the subsequent second-ratoon crop yield were not variety specific. Residual effect of glyphosate when post-harvest residue was not removed reduced sucrose yields by 13% relative to the non-treated control. Sucrose yield in the second-ratoon crop was not reduced when glyphosate was applied and residue was removed. When treated with glyphosate the previous year, residue retention reduced stalk population and photosynthesis in the second-ratoon crop compared to when residue was removed. Late-season glyphosate ripener applications are not recommended due to a lack of response by sugarcane coupled with the potential of residual injury effects caused by translocation of glyphosate into the crown, especially if post-harvest residue cannot be removed prior to the emergence of the subsequent ratoon crop. Keywords: glyphosate, growth regulators, ratoons, ripeners, sugarcane

La aplicacion de glifosato a fin de ternporada como madurador; junto con la retencion de los residues post cosecha, lmpactan sobre los rendimientos subsiqulentes del rebrote Diferentes causas de stress vegetal, cuando se present an juntas, pueden producir efectos agravados en el crecimiento y rendimiento de la caria, Los objetivos de este experimento fueron determinar: 1) si la aplicaci6n tardia en la temporada (nov. 1) del glifosato como madurador aumenta el rendimiento de sacarosa en los cuatro cultivares comerciales de caria de azucar, cultivados en Louisiana, EEUU. 2) las diferencias de los cultivares en susceptibilidad al dana por glifosato en los sucesivos cultivos de rebrote y 3) si el stress del glifosato residual en la subsiguiente cosecha de rebrote se agrava por la retenci6n del residue post cosecha. EI glifosato fue aplicado el 10 de noviembre (0.21 kg a.i. ha') al primer rebrote. Dos semanas despues de cosechado el primer rebrote la capa de residue fue dejada

0

fue completamente removida por quemado. Independientemente

de la variedad, la aplicaci6n al fin de la temporada del madurador no produjo aumento en el rendimiento de sacarosa en el primer rebrote y los efectos residuales del glifosato ell el cultivo de segundo rebrote no fueron especificos para cada variedad. Los efectos residuales del glifosato cuando no se retir6 el residue post cosecha redujeron el rendimiento de sacarosa en un 13% en relaci6n al control no tratado. EI rendimiento de sacarosa en el cultivo de segundo rebrote no se redujo cuando se aplic6 glifosato y se retire el residue. Cuando el tratamiento con glifosato se hizo el ario anterior la retenci6n del residuo redujo la poblaci6n de tallos y la fotosfntesis en el cultivo de segundo rebrote, en comparaci6n con 10 que ocurre con el retire del residuo. Las aplicaciones de glifosato como madurador a fin de temporada no se recomiendan debido a la falta de respuesta de la cafia de azucar adernas de los efectos potenciales de dana residual producido por la translocaci6n del glifosato a la corona, en particular si el residue post cosecha no puede ser retirado antes de la emergencia del subsecuente cultivo de rebrote.

Apticacao de maturadores de glifosato no final da ternporada em conjunto com a retencao de residues pos-colheita lrnpacta em rendlmento de soca subsequente Diferentes fontes de estresse da planta, quando juntos, pode ter efeitos mais graves no crescimento e produtividade de cana. Os objetivos deste experimento foram determinar: 1) se no fim da temporada (01 de novembro) a aplicacao de glifosato maturador aumenta

0

rendimento da sacarose

nas quatro variedades mais comuns de cana-de-acucar comercial cultivadas no Louisiana, EUA, 2) diferencas entre cultivares na susceptibilidade

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a lesao residual de glifosato em cultivos sucessivos de soca, e 3) se a ten sao residual de glifosato na soca subsequente e agravada pela presence de residuo p6s-colheita. 0 glifosato foi aplicado em 01 de novembro (0,21 kg ha') para a primeira colheita da soca. Duas semanas depois que a primeira soca foi colhida, a cobertura de residuos da cultura foi manti do com autorizacao ou foi completamente removido pela combustao, Independentemente da variedade, a aplicacao de maturadores no fim da temporada nao ofereceu nenhum aumento no rendimento de sacarose na primeira soca, e 0 efeito residual de glifosato na producao subsequente da segunda safra de soca foi especifica para cada variedade. 0 efeito residual de glifosato quando residuo p6s-colheita nao foi removido, reduziu a producao de sacarose em 13% em relacao ao controle nao-tratado. A produtividade de sacarose no segundo cultivo da soca nao foi reduzida quando 0 glyphosate foi aplicado e 0 residuo foi removido. Quando tratados com glifosato no ana anterior, a retsncao de residuos reduziu a populacao de colmos e fotossintese no segundo cultivo da soca comparado quando o residue foi removido. Aplicac;;6es de maturadores de glifosato no final da temporada nao sao recomendados devido

a falta de resposta da cana,

associado ao potencial de efeitos de lesao residual causada pela translocacao do glifosato para a coroa, especial mente se

0

residuo p6s-colheita

nao pode ser removido antes do surgimento da cultura de soca subsequente.

Introduction High incident light, low night temperatures, and low soil moisture later in the harvest season promote natural ripening of sugarcane by retarding vegetative growth and increasing sucrose accumulation (Legendre, 1975; Robertson et al., 1999). These conditions do not exist at the beginning of harvest in Louisiana because the shortness of the growing season so artificial ripening with the use of herbicidal chemicals is used to hasten maturation to increase sucrose yields (Nickell, 1984). The only ripener labeled for use in Louisiana is glyphosate (Dalley and Richard, 2010). Globally, glyphosate is the most widely used sugarcane ripener (Soloman and Li, 2004). Glyphosate is not labeled for use in plant-cane crops because of potential phytotoxicity to crown buds which could adversely affect ratoon regrowth, stalk population, and yields (Legendre et al., 2002). Ratoon crops develop from basal buds of the previous crop, whose germination and growth progressively decrease during the crop cycle (Dissanayake et al., 1998). Thus, any stress affecting these buds can potentially reduce yields in the remaining crop cycle. The time necessary for optimum ripener-induced maturation increases glyphosate translocation into the nodes, internodes, and basal buds (Nomura et al., 1986). Translocation into basal buds leads to slow crop establishment in the spring with glyphosate-treated sugarcane. On the other hand, major reductions in yield have only been reported at higher than recommended rates (0.90 kg ai ha') and treatment to harvest intervals exceeding 49 days (Legendre et a/., 1980; Legendre et a/., 2002). In South Africa, ratoon crops of only certain cultivars had leaf chlorosis and stunted growth after recommended rates of glyphosate were applied to the previous crop, but these early-season effects did not affect crop yields the following year (Donaldson and Inman-Bamber, 1982). Chemical ripeners can have contrasting effects depending on the sugarcane variety. Morgan et a/. (2007) demonstrated varying changes in sucrose content from 43 Australian sugarcane cultivars treated with glyphosate. Moreover, Kingston et al. (1991) in a multi-year study at multiple locations reported varying response of two cultivars; H 56-752 showed a positive ripener response in 80-92% of the trials while CP 44-101 had a response in only 50-67% of the trials. Similar findings following ripener applications of glyphosate were shown in other regions of Australia, South Africa, Florida (USA), and Louisiana with varying degree depending on variety and rate applied (Dalley and Richard, 2010; Dusky et a/., 1986; Legendre and

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Finger, 1987; McDonald etal., 2000, 2001; Morgan eta/., 2007; Roston, 1989). Several factors can compound the residual herbicidal effects of glyphosate ripener usage on the subsequent ratoon crop. Certain cultivars are more sensitive to glyphosate applications and exhibit reduced ratoon regrowth when applications were made the previous year (Donaldson and Van Staden, 1989; Morgan et a/., 2007). Environmental conditions at application timing, during the harvest of ripener-treated cane, and during the regrowth period affects the level of injury (Clowes, 1978; Donaldson and Inman-Bamber, 1982). Moisture stress, poor fertility, and post-harvest residue retention have been associated with compounding the glyphosate stress on the subsequent crop (Clowes, 1980; Donaldson and Inman-Bamber, 1982). Viator et a/. (2008) demonstrated that the two stresses of post-harvest residue retention and ripener residual effects worked independently of each other with 'LCP 85-384'. Yields were reduced with full retention of the post-harvest residue generated during greencane harvest due to cool, wet soil conditions and autotoxic leachates relative to where the residue was removed (Viator et al., 2005, 2006). Moreover, the only glyphosate treatment that had a negative residual effect was when the treatment to harvest interval was 60 days after treatment (DAT) relative to 40 and 50 DAT. More recent research has demonstrated that the newer cultivars of sugarcane in Louisiana, such as HoCP 96-540, are more sensitive to post-harvest residue retention, and therefore may be more susceptible to compounded stresses including the use of ripener (Viator et a/., 2009). Chemical ripeners are normally used for improving sucrose content during the incline phase of cane maturity when cane is considered immature (Romero et a/., 2001; Soloman and Li, 2004) which normally occurs during the beginning and middle portion of the harvest period (unpublished maturity data). In Louisiana it is currently recommended that approximately the last third of the harvested crop not be artificially ripened, as sugarcane will have matured naturally and no increase in recoverable sucrose should be expected (Legendre, 2009). However, some growers still apply a late-season ripener to insure the cane is ripened to its maximum potential, and this excessive ripener application is often encouraged by millers who subsidize the cost of ripener application (Soloman and Li, 2004). Thus, late-season applications may not be warranted and because of the potential for glyphosate to be translocated into the crown may actually have a negative residual effect in the subsequent ratoon crop. The objectives of this experiment were to determine if:

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1) late-season (Nov. 1) glyphosate ripener application increases sucrose yield in the four common commercial sugarcane cultivars grown in Louisiana, 2) cultivar differences in susceptibility to injury from residual glyphosate in successive ratoon crops, and 3) the stress of residual glyphosate on the subsequent ratoon crop is compounded by the presence of post-harvest residue.

Materials and methods

nondestructive sampling on three 1 m 2 sections of row in each plot using a single leaf chamber on three of the newest fully expanded leaf with a CIRAS-2 portable photosynthesis system (PP Systems International, Inc., Amesbury, MA). Cane yield (t ha') in the first- and second-ratoon crops was determined by mechanically harvesting the plots and weighing the cane using a modified high-dump field transportation wagon equipped with electronic load cells (Johnson and Richard, 2005). The two first-ratoon crops were harvested on December 1, 2005 and December 3, 2006; the subsequent second-ratoon crops were harvested on October 15, 2006 and October 16, 2007. Theoretical recoverable sucrose (TRS) level was assessed from a randomly collected billet (stalk piece) sample from each plot using the core press method (Dalley and Richard, 2010; Johnson and Richard, 2005). Sucrose yield is the product of cane yield and TRS levels. All data were analyzed using SAS with PROC MIXED (SAS Institute, 2001) with variety, ripener treatments and residue treatments as fixed variables and experiment and replication as random variables. Differences among treatment least square means were compared using the pdiff option (Saxton, 1998) at the 0.05 probability level.

In 2004 and 2005, sugarcane was planted on August 15 and 17 to adjacent fields on a Cancienne silt loam (fine-silty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquepts) at the USDA-ARS- Sugarcane Research Unit's Ardoyne Farm located near Schriever, LA (29°38' N, 90°50' W). Progeny of heat-treated seed-cane was planted to insure high quality seed. Seed cane was hand-planted at a rate of three stalks side-by-side lengthwise in the planting furrow with a 20% overlap at each end, which is equivalent to 6 t ha'. Cane was then covered with 7.5 cm of packed soil. To insure optimum levels of weed control, metribuzin was applied at 2.5 kg ai ha" immediately after planting and a mixture of pendimethalin (2.2 kg ai ha') plus metribuzin (2.5 kg ha') was applied in early March and again in late May for Results each crop. Nitrogen, phosphorus, and potassium were applied in mid April at 135, 34, 68 kg ha', respectively, as an injected First- ratoon crop band 71 cm wide on both sides of the planted line of cane each There were no glyphosate treatment by variety interactions for all year. Sugar cane borers were controlled using tebufenozide at 0.1 kg ai ha when infestations reached thresholds defined by parameters measured, so data was pooled across all four cultivars Louisiana State University AgCenter Extension recommendations for cane yield, TRS, sucrose yield, stalk population, and stalk height (Table 1). Compared to the non-treated control, application (Legendre, 2001). In 2005 and 2006, treatments were arranged in a split-split plot of glyphosate (0.21 kg ai ha') in November did not affect any of design with sugarcane variety as whole plots, ripener application the parameters measured in this study. Cane and sucrose yields as split-plot, and residue management as split-split plot. In the for the non-treated control and glyphosate treatment were 103 whole plots, the four leading commercial cultivars grown in and 101 t ha and 13.8 and 13.6 t ha', respectively. This lack Louisiana (LCP 85-384, Ho 95-988, HoCP 96-540, and L 97-128) of treatment effect was also reflected in TRS, stalk population, were planted (Legendre and Gravois, 2004). In the split-plots, and height data. TRS for the non-treated control and glyphosate 0.21 kg ai ha glyphosate (Roundup WeatherMax®) was applied treatments was 134 and 135 kg t', while stalk population and heights were 63.3 and 62.8 thousand stalks ha and 101 and 102 to the first ratoon on November 1 and 3 in 2005 and 2006. A cm, respectively. non-treated control was also included. In split-split plots, postharvest residue was either not removed or completely removed by burning two weeks after harvest of the first ratoon. Whole plots Second- ratoon crop (cultivars), split plots (glyphosate), and split-split plots (residue) consisted of three 1.8 m wide rows that were 28, 14, and 7 m Similar to the first- ratoon crop, there were no glyphosate long, respectively. All treatments were replicated four times. On treatment by variety interactions for all parameters measured, all second- ratoon crops, stand counts were made on monthly so data were pooled across the four cultivars for cane yield, intervals beginning mid-March until late July of 2006 and 2007 on TRS, sucrose yield, photosynthesis, stalk population and stalk aim flagged section of row in each plot. In March, April and May, height (Table 2). However, there was a residue management by canopy closure was measured using digital photography. Leaf Table 1. Mean cane yield, TRS, sucrose yield, stalk height, and stalk population for area was also measured at flrst-ratoon pooled across LCP 85-384, Ho 95-988, HoCP 96-540, and L 97-128 that this time by collecting 1 m 2 were treated with 0 or 0.21 kg glyphosate ai ha applied Nov 1 ' section of plants from each plot by destructive sampling. Leaves were analyzed using a WinDIAS leaf area meter (Delta-T Devices, Cambridge, UK). Photosynthesis was

------------~-------------------------

Non-treated

recorded also at this time by

t

_G--"Iy-,-p_h_o_sa_t_e~

103A

134A

13.8A

101A

101A ~

135A

13.6A

102A ........:...........:...

63.3A

62.8A ---=~........:...~~

Means within a column followed by a different upper case letter are statistically different using the pdiff option at p = 0.05,

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late-season glyphosate coupled with oost-narvest impacts subsequent ratoon yield

Table 2. Mean cane yield, TRS, and sucrose yield for second-ratoon pooled across LCP 85-384, Ho 95-988, HoCP 96-540 and L 97-128 (whole plots) that were treated with 0 or 0.21 kg glyphosate ai ha' (split plots), and had post harvest residue removed via burning or not removed (split-split plots) Cane yield Control Residue management

No removal Removed t Means within a column followed

1168a t

103Bb

117Aa

124Aa

125Aa

116Aa

by a different upper case letter or within arowwith a lower case letter

Table 3. Mean photosynthetic rate (measured during grand growth), stalk population and height at the time of harvest for second-ratoon sugarcane pooled across LCP 85-384, Ho 95-988, HoCP 96-540 and L 97-128 (whole plots) that were treated with 0 or 0.21 kg ai ha' glyphosate (split plots), and had post harvest residue removed or not removed (split-split plots)

Residue

No removal

26.6Aa t

Removed

26.7Aa

"Means within a column followed by a difterentupper case

glyphosate treatment interaction, so data is presented separately by these two treatment structures. This interaction indicates that sugarcane responded differently to glyphosate treatments depending on the type of residue management used. When post-harvest residue was not removed on the secondratoon crop glyphosate application decreased cane and sucrose yields (103 and 11.9 t ha') relative to the t ha'). When the residue was removed glyphosate application did not significantly yields (125 and 15.0 t ha') relative to the

was removed by burning when glyphosate was applied to the previous firs-ratoon crop. Moreover, when glyphosate was not applied, there were no residue management effects on TRS in the second-ratoon crop. Similar to TRS, the stresses of glyphosate alone or residue management alone did not affect second ratoon spring shoot populations, canopy closure, or effective leaf area (data not shown); also stalk population was not affected (Table

control (116 and 13.6 by burning, however, affect cane or sucrose control (124 and 14.4

3). In other words, stalk population was reduced only with the combination of glyphosate ripener application and when post harvest residue was not removed. When the first ratoon crop was

t ha'). Thus, the residual herbicidal effect of glyphosate only occurred when post-harvest residue was not removed. Postharvest residue retention reduced cane and sucrose yield whether

treated with glyphosate, post-harvest residue retention reduced second-ratoon stalk population 6700 stalks ha' compared to where the crop residue was burned.

or not glyphosate was applied. When glyphosate was not applied, full retention decreased cane and sucrose yields (116 and 13.6 t ha') relative to where the residue was burned (124 and 14.4 t ha'), When glyphosate was applied, full retention of crop residue decreased cane and sucrose yields (103 and 11.9 t ha') relative to where the residue was burned (125 and 15.0 t ha'), Overall, glyphosate residual effect reduced yields only when crop residue was not removed, while post-harvest residue retention reduced yields regardless of whether glyphosate was applied Nov 1 in the previous first ratoon. Moreover, second-

Stalk height in the subsequent second-ratoon crop was not affected by glyphosate applications or residue management. However, differences in photosynthetic rates were similar to differences in TRS and stalk population in that rates were only reduced when both crop residue was retained and glyphosate was applied. When treated with glyphosate the previous year, post-harvest residue retention reduced photosynthesis in the second ratoon by 2.3 umol m-1s-t, which is an 8% reduction relative to where the residue was burned.

Discussion

ratoon cane and sucrose yields losses were greatest when residue was retained following a glyphosate ripener application to the first-ratoon crop. When glyphosate was not applied, full

The Roundup WeatherMax® label for sucrose enhancement in

retention reduced cane and sucrose yields both by 6%; however, when glyphosate was applied, full retention reduced cane and sucrose yields by 17 and 21 %. Similar yield reductions with additive stress effects were not consistent across yield components of TRS, stalk number, and stalk height. Glyphosate application did not affect TRS regardless of the type of residue management used. However, full retention of residue reduced TRS by 5 9 kg-1 relative to where the residue

Louisiana stipulates a treatment to harvest interval of 21 to 49 d (Monsanto Company, 2007); our study showed no sucrose yield advantage at 49 days after treatment on Nov. 1 for first-ratooncrops. Prior research in South Africa and Louisiana indicated that a 42 d interval was the optimal harvest interval because, after this time, decreases in stalk mass brought about by the inhibition of apical growth negated increases in sucrose content (Clowes, 1980; Legendre et al., 1980). Similar reductions in cane yield that

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negated increases in sucrose content were not observed in our study. One reason is that at this time of year in Louisiana there is very little stalk elongation occurring so cane yield is not affected. In fact, glyphosate had no effect on sucrose content, cane yield, sucrose yield, stalk population, or stalk height for a Nov. 1 application. Viator et al. (2008) reported increases of 18 kg t' (16%), for glyphosate applications compared to the non-treated control when cane was treated at the beginning of the harvest season (Oct. 1) in Louisiana to sugarcane 'LCP 85-384'. A possible reason why there was no effect with the lateseason ripener application is that the cane was physiologically mature when it was treated with ripener; this time period is usually considered an optimal period for maximum natural ripening (USDA-ARS Sugarcane Research Unit unpublished maturity studies). The degree of artificial ripening is dependent on the maturity of the tissue; the greatest response to ripeners is reported in young, actively growing cane compared to older, mature, and slowly-growing cane. Furthermore, end of the season ripener applications have shown poor responses (Roston, 1973). The physiological stage of the cane at the time of application affects ripener activity (Nickell, 1984), thus the particular time during the growth season that ripener is applied influences efficacy (Cutino et al., 1992). Glyphosate application usually results in decreased stalk weight, stalk height, and cane yield (Legendre et al., 2002). This was not demonstrated in this study because cane was not actively growing at this point. Clowes (1980) also reported a lack of response during winter months similar to the environmental conditions in the current study. In the current study, the lack of yield response in first ratoon and the carry-over herbicidal effects when coupled with crop residue retention were consistent across four cultivars possibly due to optimal maturity levels for all cultivars tested. Past research indicated that cultivars differ greatly in their response to a glyphosate application (Millhollon and Legendre, 1996). Cuenya and Mariotti (1986) reported that genetic differences in maturation are often masked when the crop reaches full maturity, which was the time period when the current study was conducted. Prior research also indicated that genotypes responded differently to glyphosate applications in the subsequent crop (Clowes and Inman-Bamber, 1980; Dusky et al., 1986; Millholon and Legendre, 1996; Rostron, 1989). Morgan et a/. (2007) reported complete stand failure in the subsequent ratoon crop with one of 43 cultivars tested in Australia. The residual herbicidal effect of glyphosate ripener was evident only when coupled with full retention of crop residue. Previous research indicated a lack of interaction of residue and ripener application on yields of the subsequent second-ratoon crop of 'LCP 85-384' (Viator et al., 2008); this variety was included in the current study. However, since the time period between the study conducted by Viator et al. (2008), this variety has had a great loss in vigor due to susceptibility to brown rust (caused by Puccinia melanocephala Hand P. Sydow). Other research has also shown a reduction of vigor of 'LCP 85-384' over time (Viator et al., 2009). Prior research has demonstrated residual effects of glyphosate into the subsequent ratoon crop when coupled with stress such as drought (Donaldson and Van Staden, 1989). In the current study, the effects of post-harvest

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residue were consistent across glyphosate treatments, while the residual herbicidal effects of glyphosate were only present when coupled with full residue retention. This indicates that postharvest residue may be the more dominant stress. Donaldson and Van Staden (1989) reported that glyphosate residual effects and other stress effects on the subsequent ratoon crop were linked more to the stress, such as drought stress, than to its sensitivity to glyphosate. There are several possible explanations for glyphosate residual effects. Radioisotope experiments have shown that glyphosate is distributed into other portions of the sugarcane plant such as the stalk and roots (Hilton et al., 1976; Sprankle et al., 1975); germination of nodal buds or ratoon shoots mobilizes the glyphosate residues into these areas of metabolic activity. The analysis of several ratoon shoots after removal of all the above ground treated plant and existing tillers showed that radioactivity stored in the stool had moved into new growth (Nomura et al., 1986). Greenhouse studies using cultivars grown in Louisiana suggest that glyphosate can reduce sugarcane growth by increasing the severity of root rot, which delays emergence and slows growth (Dissanayake et al., 1998). Prior research also indicated yield losses due to residual glyphosate effects only occur when the residual glyphosate stress was accompanied by another stress such as inadequate moisture (Donaldson and Inman-Bamber, 1982). Prior research has also indicated that in Louisiana, crop residue retention slows soil warming in spring, retains more soil moisture, and releases autotoxic compounds, all of which delay emergence and growth (Viator et al., 2005, 2006). This coupled stress may have the same effects as that reported by drought (Donaldson and Inman-Bamber, 1982; Gosnell and Lonsdale, 1974). Moreover, in wet areas of Indonesia, glyphosate adversely affected growth of the subsequent ratoon crop (Soloman and Li, 2004). Clowes (1980) reported yield loss with glyphosate residual effects and retention of post-harvest residue, but these effects were inconsistent across seasons. Louisiana producers should not apply ripener where post-harvest residue cannot be removed. Moreover late-season applications are also not recommended due to a lack of economic response and the potential of residual effects because of translocation into the crown especially if coupled with an additional stress such as residue retention.

References Clowes, M. (1978) Early and late season chemical ripening of sugarcane. Proc. South Afr. Sugar Techno!. Assoc. 52: 160-165. Clowes, M. (1980) Ripening activity of the glyphosate salts MON 8000 and Roundup. Proc. Int. Soc. Sugar Cane Techno!. 54(1): 676-

693. Clowes, M. and Inman-Bamber, N.G. (1980) Effects of moisture regime, amount of nitrogen applied and variety on the ripening response of sugarcane to glyphosate. Proc. S. Afr. Sugar Cane Techno!. Assoc. 54(1): 127-133. Cuenya, M.1. and Mariotti, J.A. (1986) Selection of sugarcane for quality components and ripening ability. Proc. Int. Soc. Sugar Cane Techno!. 56(1): 429-439. Cutino, A.L., Creach, I., Guevara, H., Gonzalez-Tellez, E, Pinero, J., Gomez, M., Fernandez, 0., Cobas, D. and Diaz, J.C. (1992) Fluazifop,

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ethophon, glyphosate and ethephon-rftuazifop as ripeners of six

McDonald, L., Morgan, T. and Jackson, P. (2001) The effect of

sugarcane cultivars in Cuba. Proc. Int. Soc. Sugar Cane Technol. 21(2):

ripeners on the CCS of 47 sugarcane varieties in the Burekin. Proc.

5-14.

Aust. Soc. Sugar Cane Technol. 23: 102-108

Dalley, C.D. and Richard, E.P. Jr. (2010) Herbicides as ripeners for sugarcane. Weed Sci. 58: 329-333. Dissanayake, N., Hoy, J.W and Griffin, J.L. (1998) Herbicide effects on sugarcane growth, Pythium root rot, and Pythium arrhenomanes.

Phytopathology 88(6): 530-535. Donaldson, R.A (1994) Responses of some sugarcane varieties to standard and combination ripener treatments. Proc. South Afr. Sugar

Cane Technol. 16(1): 7-16. Monsanto Company (2007) Roundup WeatherMax Herbicide. Available

at

http://www.greenbook.netiDocs/Label/L68714.pdf.

(Verified 22 July, 2010). Monsanto Company, St. Louis, MO. Morgan, 1., Jackson, P. McDonald, L. and Holtum, J. (2007)

Cane Technol. Assoc. 62: 19-22. Donaldson, RA, and Inman-Bamber, N.G. (1982) Residual effect of glyphosate as a ripener on sugarcane. Proc. South Afr. Sugar Cane

Chemical ripeners increase early season sugar content in a range of sugarcane varieties. Aust. J. Agric. Res. 58: 233-241. Nickell, L.G. (1984) Sucrose increases with bioregulators. ACS

Technol. Assoc. 56(1): 122-124. Donaldson, RA and Van Staden, J. (1989) A review of chemical used as ripeners of sugarcane in South Africa. Proc. Int. Soc.

Sugarcane Technol. 20: 647-655.

Sym. Ser. 257(1): 101-112. Nomura, N., Hayamichi, Y. and Hilton, W (1986) Some physiological effects from glyphosate applied to sugarcane foliage. Proc. Int. Soc.

Dusky, JA, Kang, M.S. Glaz, B. and Miller, J.D. (1986) Response of eight sugarcane cultivars to glyphosine and glyphosate ripeners. J. Plant Growth Regul. 4: 225-235.

Sugar Cane Technol. 19(1): 284-297. Robertson, M.J., Muchow, R.C. and Wood, A.W. (1999) Developing guidelines for the length of drying off of irrigated sugarcane before

Gosnell. J.M. and Lonsdale, J.E. (1974) Some effects of drying off before harvest on cane yield and quality. Proc. Int. Soc. Sugar Cane

Technol. 15: 701-712. Hilton, H.W, Nomura, N.S. Kameda, S.S. and Yauger, WL. (1976) Some patterns of herbicide and growth regulator intake, persistence, and distribution in sugarcane. Archives. Environ.

Millholon, R.W and Legendre, B.L. (1996) Sugarcane yield as affected by annual glyphosate ripener treatment. J. Am. Soc. Sugar

Contam. 4(4):

385-394. Johnson, R.M. and Richard, E.P. Jr. (2005) Sugarcane yield, sugarcane quality, and soil variability in Louisiana. Agron. J. 97(3): 760-771. Kingston, G., Hurney, AP. and Kwint, P. (1991) Chemical ripening of sugarcane to improve early Season CCS. Proc. Aust. Soc. Sugarcane

Technol. 13: 110-115 Legendre, B.L. (1975) Ripening of sugarcane: Effects of sunlight, temperature, and rainfall. Crop Sci. 15(3): 349-352. Legendre, B.L. (2001) Sugarcane Production Handbook. www. Isuagcenter.com/Communications/pdfs_bak/pub2859sugarcane.PDF (verified 12 June 2010). LA AgCenter. Baton Rouge, LA Legendre, B.L. and Finger, C.K. (1987) Response of sugarcane varieties to the chemical ripener glyphosate. Proc. Plant Growth Regul. Soc. 14: 479-484. Legendre, B.L. (2009) Sugarcane RipenerRecommendations for2009. http://www.lsuagcenter.com/M CMS/RelatedFiles/% 7B9DC4 E57676B6-440A-88B8-25E3902327F4 % 7D/Sugarcane+ Rippener+Recom m endations2009.pdf (verified 12 June 2010). LA AgCenter. Baton Rouge, LA

harvest in Burdekin. Proc. Aust. Soc. Sugar Cane Technol. 21(1): 196-202. Romero, E.R., Scandaliaris, J.Y., Zamora, F.P. and Bulacio, A. (2001) Agronomic, industrial and economic impact of sugarcane chemical ripening. Proc. Int. Soc. Sugar Cane Technol. 24: 161-163. Roston, H. (1973) The effects of chemical ripeners on the growth, yield, and quality of sugarcane in South Africa and Swaziland. Proc. S.

Afr. Sugar Technol. 47: 191-200. Roston, H. (1989) The response of sugarcane varieties to chemical ripeners in the Natal midlands. Proc. S. Afr. Sugar Cane Technol.

Assoc. 63(1): 164-166. SAS Institute (2001) Proc. mixed. SAS for Windows. Ver. 8.02. SAS Inst., Cary, NC. Saxton, A.M. (1998) A macro for converting mean separation output to letter groupings in proc mixed. Available http:\\www2.sas. com/proceedings/sugi23/Stats/p230.pdf. (verified 27 Jan 2006). SAS Institute, Cary, NC. Soloman, S. and Li, Y. (2004) Chemical ripening of sugarcane: Global progress and recent developments in China. Sugar Tech. 6(4): 241-249. Sprankle, P., Meggitt, WF. and Penner, D. (1975) Absorption, action, and translocation of glyphosate. Weed Sci. 23: 235-240. Viator, R.P., Johnson, R.M. and Richard, E.P. Jr. (2005) Challenges of postharvest residue management in the Louisiana sugarcane

Legendre, B.L., Martin, FA and Dill, G.M. (1980) Preliminary investigations on the effects of Polado on regrowth of sugarcane in Louisiana. Proc. Plant Gro. Reg. Working Group. 7(1): 148. Legendre, B.L., Gravois, K., Bischoff, K. and Griffin, J.L. (2002) Efficacy of Polado, Arsenal and Fusilade as chemical ripeners for Louisiana. 2002 Sugarcane Annual Progress Report. LA. St. Univ. Ag. Cen., Baton Rouge, LA. Legendre. B.L. and KA Gravois (2004) 2004 Sugarcane Annual

Progress Report. La. St. Univ. Ag. Cen. Baton Rouge, LA.

industry. Proc. Int. Soc. Sugar Cane Technol. 25(2): 238-245. Viator, R.P., Johnson, R.M., Grimm, C.C. and Richard, E.P. Jr. (2006) Allelopathic, autotoxic and hormetic effects of postharvest sugarcane residue. Agron. J. 98(6): 1526-1531. Viator, R.P., Johnson, R.M., Richard, E.P. Jr., Waguespack, H.L. and Jackson, W. (2008) Sugarcane post-harvest residue retention and non-optimal ripener applications reduce second ratoon yields. Agron.

J. 100: 1769-1773.

McDonald, L., Morgan, 1. and Kingston, G. (2000) Chemical

Viator, R.P., Johnson, R.M. and Richard, E.P. Jr. (2009) Mechanical

ripeners: An opportunity for the Australian sugar industry. Proc. Aust.

removal and incorporation of post-harvest residue effects on sugarcane

Soc. Sugar Cane Technol. 22: 290-95.

ratoon yields. Sugar Cane Inter. 27(4): 149-152.

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