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Nutsedge Time of Removal in Ratoon Sugarcane. C. Rainbolt and S. Chandramohan Everglades REC, University of Florida. Introduction. Sugarcane is a large subtropical grass A perennial crop that is harvested annually in Florida Typically 1 plant crop and 2-3 ratoon crops
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Nutsedge Time of Removal in Ratoon Sugarcane C. Rainbolt and S. Chandramohan Everglades REC, University of Florida
Introduction • Sugarcane is a large subtropical grass • A perennial crop that is harvested annually in Florida • Typically 1 plant crop and 2-3 ratoon crops • Intra-row cultivation is limited in ratoon crops • Weed pressure tends to increase as the crop ages
Nutsedge and Sugarcane • Purple and yellow nutsedge are common in Everglades Agricultural Area sugarcane fields • In containers, Shine and Duchrow (2000) found that purple nutsedge densities as low as 50/m2 reduced sugarcane tiller number and stalk weight • Etheredge et al. (2006)reported that low initial tuber densities reduced sugarcane biomass in pot studies
Objectives • To determine if purple nutsedge interferes with ratoon sugarcane growth and yield • If interference does occur, when should nutsedge be removed
Materials and Methods • Experimental design was a randomized complete block with four replications • Plots were 4 rows (20 ft) by 70 ft long • Sugarcane cultivar was CP72-2086 • Treatments included purple nutsedge removal 3, 6, and 9 weeks after harvest (WAH) and one control treatment (no nutsedge removal) • Nutsedge was removed by treating with halosulfuron at 0.047 lb/A at the initial removal date and a sequential treatment 3 weeks later
Materials and Methods • Initial nutsedge plant and tuber number and biomass were collected in a 0.4 m2 quadrat • Sugarcane stalk population (early season and millable) were counted • 10 stalk samples were collected and weighed to determine stalk weight and sugar analysis • Leaf area index was measured using a SunScan leaf area meter
Nutsedge density • Initial tuber density was 165 m2 • Tuber density was 244 m2 9 WAH • Herbicide applications provided 99 to 100% control
LSD (0.05) = 0.94 AB A AB B
Summary • Initial results indicate that ratoon sugarcane stalk populations, stalk weight, and sugar yield were not significantly affected by nutsedge time of removal • Trials will be repeated at multiple locations in 2008
Why does ratoon sugarcane appear to be more competitive than other crops? • Plant cane is often harvested late when temperatures are warm and cane is growing quickly • Ratoon cane is likely more competitive than plant cane • Sugarcane “grand growth period” occurs in summer months following canopy closure • Purple nutsedge is sensitive to shading