The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Monday, January 28, 2008
33
Effect of Different Herbicides on Switchgrass Establishment
M. Anowarul Islam, Twain J. Butler, and Chengjun Huo. Forage Improvement Division, The Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401
Switchgrass (Panicum virgatum L.) is a warm-season, long-lived perennial grass. Recently this grass has been identified as a potential bioenergy crop. Establishment is the number one limitation for widespread use of this grass. Till to date, there is no herbicide that has been labeled for the switchgrass. The objective of this study is to find out appropriate herbicide that would control weeds to enhance establishment of switchgrass. The study is being conducted in the southern Oklahoma with 14 ALS (Amino Acid Synthesis Inhibitors) herbicides, one untreated control on two genotypes of switchgrass (upland type, CaveNRock; lowland type, experimental line NFGA993). The experimental design is a randomized block with three replications. In fall of 2006, switchgrass was planted on a loamy soil and only the pre-emergence herbicide (PRE) treatments were applied. In 2007, switchgrass was planted in spring at two locations, and treated with both PRE and post-emergence (POE) herbicides on loamy and sandy-loam soils. POE herbicides were applied at 5th leaf stage on loamy soils and 3rd leaf stage on sandy-loam soils. Seedling counts, plant height, weed control and injury were recorded at 30 and 60 days after treatment. Some PRE herbicides (e.g. FirstRate and Strongarm) seemed to be effective in weed control with greater seedling count (4-10 seedlings/sq.ft) and less injury (0-10%). None of the POE only herbicides seemed to be effective controlling the weeds without excessive switchgrass injury at 5th leaf stage. However, FirstRate followed by Journey at 5th leaf stage controlled weeds with greater seedling count (9 seedlings/sq.ft) and plant height (11 inches), and had little to intermediate injury (3-32%) on loamy soils while, FirstRate followed by Atrazine at 3rd leaf stage offered similar results on sandy-loam soils. These data indicate that growth stage and time of application are important factors for ALS herbicide application on switchgrass.