|Richard Jr, Edward|
Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2005
Publication Date: July 20, 2005
Citation: Dalley, C.D., Richard Jr, E.P. 2005. Sugarcane (saccharum spp.) Response to the Herbicide Flumioxazin. Journal of the American Society of Sugar Cane Technologists. 25:104. Available: http://www.assct.org/journal/journal.htm Technical Abstract: The herbicide flumioxazin (Valor®) recently received a supplemental registration for weed control in sugarcane. Flumioxazin inhibits protoporphyrinogen oxidase, which results in the formation of oxygen radicals which cause cell membrane degradation and ultimately death in susceptible plants. Only one other herbicide that is registered for use in sugarcane, sulfentrazone, is similar in its mode of action. Experiments were initiated in October, 2000 and September 2001, to determine potential for injury and yield reduction from flumioxazin applications in plant-cane and successive first-ratoon crops of three of the most common sugarcane varieties (‘LCP 85-384’, ‘HoCP 85-845’, and ‘HoCP 91-555’) currently grown in Louisiana. In plant-cane, flumioxazin was applied preemergence (PRE) at 0.28 and 0.42 kg ai/ha immediately following planting, postemergence (POST) at 0.28 kg/ha approximately 6 weeks after planting (FPOST), in March (0.28 kg/ha) as an early-spring POST (ESPOST) application, and in May (0.28 kg/ha) following layby cultivation as a postemergence-directed spray (PDS), along with sequential applications at FSPOST followed by PDS (each at 0.28 kg/ha). In first-ratoon sugarcane, flumioxazin was applied ESPOST (0.28 and 0.42 kg/ha), as a late-spring POST (LSPOST) application in April (0.28 kg/ha), as a PDS at layby (0.28 kg/ha), and as sequential applications at LSPOST (0.28 and 0.42 kg/ha) each followed by a PDS application (0.28 kg/ha). Sugarcane injury due to flumioxazin applications consisted primarily of necrosis of treated leaves and stunted growth, and was most pronounced (25 to 30%) when applied as a LSPOST application. Injury also occurred when flumioxazin was applied as an ESPOST or as a PDS treatment at layby. Stalk height (recorded in August of each year) reductions of 15 to 28 cm occurred when flumioxazin was applied in sequential applications in both plant- and first-ratoon sugarcane. LSPOST applications of flumioxazin reduced sugarcane yields by 7 to 11%, and sequential applications reduced yields by 7 to 37% in plant-cane and by 10-19% in first-ratoon sugarcane. PRE and ESPOST treatments were generally similar to sugarcane receiving no flumioxazin application. PDS applications reduced yield in 4 of 6 year by variety observations in plant-cane, but did not significantly reduce yield in the first-ratoon crop. In plant-cane, ‘LCP 85-384’ appeared to be least tolerant of flumioxazin applications as yield was reduced by all three springtime applications in 2001 and at all six application timings in 2002, while ‘HoCP91-555’ appeared to be most tolerant of flumioxazin, as yield was reduced by all springtime applications in 2001, but only by sequential applications in 2002. In first-ratoon sugarcane, all varieties responded similarly. To avoid risk of yield loss, flumioxazin should not be applied as an over-top POST application in actively growing sugarcane, and care should be taken to minimize spray contact with sugarcane leaves when applied as a PDS at or after layby cultivation.