Sustainability of micro-clover lawns for integrated pest and pollinator management

Lawns are an integral part of American culture. Runoff or leaching of nitrogen fertilizers from traditional turfgrass lawns contributes to water pollution, and such lawns are susceptible to pests and provide few resources for pollinators. One approach for creating sustainable lawns is to incorporate leguminous nitrogen-fixing plants; e.g., white clover, Trifolium repens into existing turfgass swards. 'Dutch White clover" (DWC) is a ubiquitous clover landrace found in landscapes. Intermixed with grasses, however, DWC forms patches which reduce uniformity so it is often considered a weed. Recently, several dwarf white clover varieties (e.g., "microclover", "miniclover") were selected for small leaf size and low growth habit allowing them to tolerate low mowing and blend with cool-season turf without clumping. The dwarf clovers supply N to the grass and together they can produce a dense canopy that resists weed establishment. Nothing has been published on entomological aspects of dwarf clover in pure stands or intermixed with turfgrass. We established field plots with combinations of DWC, two types of dwarf clovers, or tall fescue in monoculture or mixed swards and compared pests, natural enemies, and pollinators therein. Predator and earthworm communities were similar in all plot types. Clover monocultures were resistant to white grubs, but clover in dicultures failed to provide associational resistance to tall fescue. Dwarf clovers were as attractive as DWC to bees and supported similar bee assemblages. Tall fescue foliar N content and N/C ratio were elevated in diculture with clovers. Other strengths and limitations of clover lawns are discussed.