Presentation on theme: "Evaluation of a Biological Control Agent for Control of Root-Knot Nematode, Meloidogyne marylandi, on Turfgrass Rachel A. McGregor and Travis R. Faske."— Presentation transcript:
Evaluation of a Biological Control Agent for Control of Root-Knot Nematode, Meloidogyne marylandi, on Turfgrass Rachel A. McGregor and Travis R. Faske Department of Environmental and Agricultural Management, Tarleton State University, Stephenville, TX Introduction Meloidogyne marylandi, root-knot nematode, is a widely distributed pest of turfgrass in Texas (Starr et al., 2007). This root-knot nematode is frequently associated with turfgrass exhibiting various symptoms of decline and poor growth (Fig. 1). Female root-knot nematodes are located on turfgrass roots which can exhibit slight galling (Fig. 2). Despite its distribution and importance on turfgrass few studies have investigated practices to manage this nematode species. Bacillus firmus, a biological control agent, has been reported to reduce root-knot nematode populations (Giannakou and Prophetou- Athanasiadou, 2004); however, no study has evaluated the effects of Bacillus firmus on M. marylandi. Objectives 1.Evaluate B. firmus to control M. marylandi on turfgrass 2. Determine the effect of B. firmus on turfgrass quality Methods and Materials This study was conducted on a golf course putting green (cv. Mini Verde, bermudagrass) naturally infested with root-knot nematodes. Based on esterase and malic dehydrogenase isoenzymatic pattern this species was identified as M. marylandi. Nortica (Bayer Environmental Sciences), B. firmus was applied at 0, 50, 75, 90 lb/acre, and Myrothecium verrucaria, (DiTera DF, Valent Biosciences Corporation) applied at 50 lb/acre served as the industry standard. Each treatment was replicated four times in a randomized complete block design. Each treatment was applied in late March to a 25 sq. ft. (5 ft x 5 ft) plot and irrigated with 0.25 in of water. Reproduction was determined based on eggs produced on turfgrass roots. Turf response to treatment was based on a turf color rating (chlorophyll meter) turf quality rating (1=poor to 9=excellent based on color and density) and root quality (quantitative measurement, root length, and weight). Results The initial population density of root-knot nematode (RKN) was similar among plots and averaged 192.9 eggs/g of root. Thus, all plots had a moderate population density of RKN on turfgrass. No phytotoxicity was observed on plots treated with Nortica or DiTera. Nematode reproduction increased 90 days after treatment among all treatments; however no difference was observed among treatments (Fig. 3). Numerically, turfgrass treated with Nortica at 90 lb/A and DiTera at 50 lb/A had a lower reproduction index than water control. Conclusion Nematode population density and turfgrass quality varied in response to all rates of Nortica in this study. Further investigation will continue in the fall to assess B. firmus for control of M. marylandi and determine effects on turfgrass quality. Literature Cited Figure 3. Reproduction of M. marylandi on bermudagrass treated with two biological control agents. Reproduction index was calculated by dividing the final population (Pf= 90 days after treatment) by the initial population (Pi= before treatment) of nematodes sampled. Figure 4. Length of root development treated with two biological control agents 90 days after treatment. Figure 1. Decline and poor growth caused by root-knot nematode on a golf course putting green in Stephenville, Texas. Figure 2. Root-knot nematode females (yellow arrows) on bermudagrass root. Starr, J. L., Ong, K. L., Huddleston, M., and Handoo, Z. A. 2007. Control of Meloidogyne marylandi on bermudagrass. Nematropica 37:43-49. Giannakou, I. O. and Prophetou-Athanasiadou, D. 2004. A novel non-chemical nematicide for the control of root-knot nematodes. Applied Soil Ecology 26: 69–79. Turfgrass color, density, and root quality were similar among treatments at all sample dates in this study. All treatments averaged 6.8 quality index for color and density; however a quality index above 8 was observed for all plots after fertilization and aeration. Furthermore, these observations were similar to those collected with a chlorophyll meter. The average chlorophyll index increased from 199.2 (before treatment) to 453.0 (90 days after treatment), which was consistent with fertilization and turfgrass management. The average root quality rating was similar among treatments (Fig. 4). Numerically, turfgrass treated with Nortica at all rates averaged longer root length than water control.