|Richard Jr, Edward|
Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 3, 2007
Publication Date: February 5, 2008
Repository URL: http://wssa.net/Meetings/WSSAAnnual/2008.htm
Citation: Dalley, C.D., Richard Jr, E.P. 2008. Effects of Johnsongrass Density and Pre-Harvest Burning on Sugarcane Production [abstract]. Proceedings of Weed Science Society of America. 48:196. Available: http://wssa.net/Meetings/WSSAAnnual/2008.htm Technical Abstract: Johnsongrass interference with sugarcane results in substantial yield losses. However, light infestations are sometimes overlooked due to the cost and difficulty of controlling rhizomatous johnsongrass in sugarcane. Studies were conducted to examine the effect of johnsongrass density and sugarcane harvest method on sugarcane production. Johnsongrass was established during the plant-cane crop in 2002 at rates of one johnsongrass plant per 3 (light), 2 (medium), and 1 m of row (heavy) compared to weed-free sugarcane in a split-plot arrangement where sugarcane was either burned prior to harvest or harvested green. Johnsongrass pressure was allowed to increase through the third-ratoon crop (2005). In late summer, sugarcane height and density and johnsongrass panicles density were determined, except in the third ratoon where sugarcane was severely lodged and measurements could not be accurately taken. Burning of sugarcane, while positively influencing harvester efficiency, did not affect johnsongrass development or interference with sugarcane. Numbers of johnsongrass panicles in the light infestation increased from 5/m2 in the plant-cane crop to 8/m2 in the first-ratoon crop to 41/m2 in the second-ratoon crop; in the medium infestation from 6/m2 in the plant-cane crop to 10/m2 in the first-ratoon crop to 47/m2 in the second-ratoon crop; and in the heavy infestation from 8/m2 in the plant-cane crop to 14/m2 in the first-ratoon crop to 60/m2 in first-ratoon crop. Sugarcane height was not reduced by johnsongrass interference in the plant-cane crop; in the first-ratoon crop it was reduced (4%) only in the heavy infestation; and in the second-ratoon crop, heights were reduced from 183 cm in the weed free to 177 cm with light infestation, to 173 cm with medium infestation, and to 169 cm with the heavy infestation. The interference from johnsongrass reduced the number of harvestable sugarcane stalks each year. This reduction was also found in sugarcane yield which was reduced (8%) only by the heavy infestation in plant cane; in the first ratoon, yield was reduced by the medium (10%) and heavy (20%) infestation levels; in the second ratoon, yield was reduced in the light (18%), medium (29%), and heavy (40%) infestation levels; and in the third ratoon, yield was reduced in the light (23%), medium (29%), and heavy (41%) infestation levels. Johnsongrass reduced total sugarcane yield by 12% (light), 17% (medium), and 25% (heavy). The increased panicle production shows how even light infestations can expand through rhizome development as sugarcane passes through ratoon crops. The results demonstrate the importance of controlling even light infestations of johnsongrass in the plant-cane crop to avoid even greater impact of the weed in the subsequent ratoon crops of sugarcane.