Turfgrasses occupy over three times the surface area of any other irrigated crop in the continental U.S. Warm season turfgrass species (C4 photosynthesis) dominate the southeastern U.S., which is also among the most rapidly urbanizing regions in the country. Therefore, the production and planting of lawns is becoming more frequent and widespread. In addition to the massive footprint, urban and residential lawns are frequently attacked by damaging insect pests, which leads to recurrent pesticide applications, dead or dying plants, and ultimately plant replacement. Warm season turfgrasses consist of relatively few species and are produced, planted, and maintained as genotypic monocultures within a given species. We argue that current production and maintenance practices predispose warm season lawns to insect pest outbreaks. With concerns of water conservation and environmental sustainability, new strategies for creating and maintaining urban and residential lawns must be developed. The overarching objective of this project is to incorporate ecological principles into warm-season turfgrass management that reduce insect pests and increase the environmental services lawns provide. To meet this objective, we conducted a combination of laboratory, greenhouse, and a common garden field experiment to quantify the effects of turfgrass genotypic diversity on arthropods and plant quality.
Results/Conclusions
Our results suggest that there may be multiple benefits associated with increasing the genotypic diversity of warm season turfgrass lawns. This includes effects on insect pest fitness and abundance, but also effects on lawn quality that may facilitate rapid translation into industry practices. When comparing three levels of genotypic diversity (monoculture, mixture of two genotypes, and mixture of four genotypes), we see effects on caterpillar pests and sap-feeding pests under lab and greenhouse conditions. Specifically, as genotypic diversity increases, fewer caterpillars survive to adults and on average caterpillars grow smaller, suggesting they are less fit. When given a choice, caterpillars feed on monocultures over more diverse plantings, which results in less plant damage. In addition, populations of the most economically damaging pest, the southern chinch bug, increase at significantly slower rates as genotypic diversity increases. An industry survey indicates that consumers and professionals prefer more diverse plantings from an aesthetic perspective when presented with all three diversity levels. This study suggests that manipulating the genotypic diversity of residential and urban lawns may be a tractable management practice that could reduce damaging insect pests and associated pesticide and water use, and increase the sustainability of these plant systems