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ARS Home » Southeast Area » Dawson, Georgia » National Peanut Research Laboratory » Research » Publications at this Location » Publication #197384
Title: INTEGRATED VEGETATION MANAGEMENT OF COGONGRASS (IMPERATA CYLINDRICA)

Author
item Faircloth, Wilson
item PATTERSON, MICHAEL - AUBURN UNIVERSITY
item MILLER, JAMES - USDA FOREST SERVICE

Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2006
Publication Date: 7/1/2006
Citation: Faircloth, W.H., Patterson, M., Miller, J. 2006. Integrated vegetation management of cogongrass (imperata cylindrica) . Weed Science Society of America Meeting Abstracts.

Interpretive Summary: Herbicide SP consistently increased loblolly pine growth, decreased live cogongrass, and increased overall plant community diversity. Release alone was not an effective reforestation technique, however, was generally additive when combined with a SP treatment. The use of herbicides was critical to the recruitment of woody and herbaceous species other than cogongrass. No reforestation technique reduced cogongrass to acceptable levels, however, the establishment of loblolly pine was successful, thus, some productivity restored to the land.

Technical Abstract: Cogongrass [Imperata cylindrica (L.) Beauv.] is invading forest lands, especially those growing loblolly pine (Pinus teada L.) plantations. The primary research objective of this project was to investigate IVM options for the establishment or reforestation of loblolly pine into cogongrass-infested areas. The study site was located in Mobile County, AL. The experiment was a factorial arrangement that tested two herbicide site preparation (SP) treatments, two mechanical SP treatments, and two pine release herbicide treatments. Herbicide SP levels were none and a broadcast-applied tank mixture of glyphosate at 3.3 kg ae/ha, imazapyr at 0.34 kg ae/ha, and nonionic surfactant at 0.5 % v/v. Application was on October 3-4, 2001. Mechanical SP levels were a scalping treatment and none. Scalping consisted of using a bulldozer and fire plow to remove the upper 10 to 15 cm of cogongrass rhizomes and roots, folding these back upon intervening grass to create a furrow in which seedlings were planted. Scalping was performed on December 19, 2001. Release treatment levels were band-applied herbicide and none and were applied after seedling planting. In addition to the eight plots in the factorial core, a ninth treatment, termed “complete control”, was added. The nine treatments were replicated four times in a randomized complete block design. Bare-root, improved loblolly pine seedlings were hand-planted on January 15, 2002. Biomass response. In the year immediately following planting of trees, mechanical SP reduced biomass in each category. However, in the following year, regrowth occurred to an extent that mechanical SP made no treatment differences. The combination treatment of mechanical and herbicide SP reduced live grass by 98.5% compared to the non-treated check in the first year, which suggests greater than an additive effect when combined compared to a single use. Live cogongrass regrew by 8 to 18-fold by the second year on all SP treatments, and all treatments contained live grass at the 2003 harvest (780-7400 kg/ha). Other woody and herbaceous plant biomass was least in the non-treated (830 kg/ha) and greatest in the complete control (8310 kg/ha). Herbicide SP and complete control yielded the greatest recruitment of other woody and herbaceous species in both years to assist with the rehabilitation process (8310 kg/ha in year two). Herbicide SP was significantly greater than both the mechanical SP and the non-treated, while mechanical SP yielded woody and herbaceous biomass equivalent to the non-treated. Data analysis revealed few significant differences between treatments or establishment methods for live grass and other species at year two. Despite intensive control efforts, cogongrass remained a significant component of the plant community as live cogongrass comprised at least 15% of the total plant biomass through year two. Herbicide SP resulted in at least 30% other species, increasing the overall plant community diversity in those treatments. Tree response. Loblolly pine survival was equal to or exceeded 90% on all treatments including the non-treated check in years one and two after planting. Treatments with herbicide SP had greater survival, either with or without mechanical SP or release. Site preparation, whether herbicide or mechanical, yielded a significant increase in ground-line diameter (GLD) compared with no SP, while the addition of release made no difference in GLD in the first year. On average, herbicide SP and release showed an additive effect for GLD response. Tree height in year one ranged from 46.1 to 66 cm. Herbicide SP yielded 6 cm taller trees than mechanical SP unless combined with mechanical SP, in which case an antagonistic effect was found. The negative interaction of mechanical SP and herbicide SP was significant for both loblolly pine GLD and HT. One possible explanation