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ARS Home » Southeast Area » Dawson, Georgia » National Peanut Research Laboratory » Research » Publications at this Location » Publication #185108
Title: INTEGRATED APPROACHES TO COGONGRASS CONTROL ON HIGWAY RIGHTS-OF-WAY: A FOUR-YEAR SUMMARY

Author
item Faircloth, Wilson
item PATTERSON, M - AUBURN UNIVERSITY
item TEEM, D - AUBURN UNIVERSITY
item MILLER, J - USDA FOREST SERVICE

Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 1/24/2005
Publication Date: 6/1/2005
Citation: v. 12.

Interpretive Summary: none required.

Technical Abstract: Integrated vegetation management strategies were investigated for treating cogongrass infestations on highway ROW and restoring them to more desirable plant communities. Management strategies included herbicides, competitive exclusion utilizing grass and clover species, and mechanical control (mowing). Two studies were designed to compare multiple combinations of herbicides, both chemistry and timing, and competitive exclusion. In order to investigate multi-year treatments, both studies were replicated three times such that a time factor could be examined. The three series were designated as ‘regimes.’ At initiation, all three regimes were treated. In yr two of the study, only the two yr and three yr regimes were retreated. During the third and final yr of the study, only the three yr regime was retreated. Thus, each of the original test treatments could be evaluated using one, two, and three years of treatment (regimes). Study one was initiated near Loxley, AL, in 2000. Fall herbicide treatments were ranked from highest control to least control as follows at Loxley: imazapyr alone, followed by the tank-mix of glyphosate plus imazapyr, followed by glyphosate alone. Data from Loxley indicated that multiple year treatment of cogongrass was necessary for control. Mean control increased from 35% to 88% between a one and three year regime 12 months after final treatment (MAT) at Loxley, and a three year regime gave both the greatest visual control and the lowest stand densities 24 MAT. Within the three year regime, the tank mix combination of glyphosate plus imazapyr consistently increased control and decreased density versus other fall-applied herbicides. Spring re-treatment with glyphosate was needed to reduce density but not to increase visual control. The establishment of either bahiagrass or bermudagrass was not achieved in this field study. Study two was initiated at Malbis, AL. in 2001 and based on preliminary findings from Loxley. Mean control was greater at Malbis as control increased from 62% to 94% between the one and two year regimes 12 MAT. Fall-applied glyphosate plus imazapyr increased visual control and decreased stand density versus glyphosate. Spring re-treatment with glyphosate was significant for neither visual control nor stand density at Malbis. The establishment of either bahiagrass or bermudagrass was achieved only at Malbis in a two year regime. The use of cover crops between fall and spring herbicide application was inconsistent in affecting control or stand density between both locations. The three year regime has yet to be evaluated 12 MAT. A third study was designed to explore possible interaction between mowing and the herbicides imazapyr and glyphosate. The mowing study was initiated in May 2002 near Theodore, AL. Mowing was performed with a flail-type mower to a height of 8 cm, or approximately the same height as ROW maintenance crews. Mowing alone neither positively nor negatively affected growth of cogongrass at frequencies up to twice per month. A sequential (spring followed summer) application of glyphosate gave complete above-ground control at the end of year one, however, regrowth was evident at the end of year two.