Enhanced Pest Management with Cover Crop Mulches

Living and dead plant vegetation on the surface of soils can provide opportunities for regulating pest populations in no-tillage production systems. Cover crops generate substantial quantities of surface vegetation and residue that can be managed to enhance control of pests. Research at the Beltsville Agricultural Research Center has shown that weed germination and emergence is inhibited by high levels of cover crop mulch, that small-seeded annual weeds are particularly susceptible to suppression by mulches, and that herbicide use can be reduced when cover crops are incorporated into cropping systems. Growing mixtures of legume and cereal cover crops is a particularly effective way to produce large quantities of cover crop residue for weed suppression. Mulches with a high surface area-to-soil area ratio and a low amount of internal empty space are most highly correlated with inhibition of weed emergence. Foliar diseases can be reduced by a cover crop mulch, primarily by preventing dispersal of pathogen propagules through splashing and/or wind-borne processes. Cover crops can suppress establishment of soil-inhabiting herbivores such as Colorado potato beetle by disrupting emergence and migration behavior. Reduction of weed and pest populations by cover crops has reduced or eliminated crop yield loss caused by these organisms. INTRODUCTION Holistic management principles and a shift to a systems approach for crop protection are vital to combating the escalating economic and environmental consequences of agricultural pests. In conventional pest management strategies, pesticides typically constitute the first line of defense. In contrast, an ecological-based, systems approach focuses on preventive practices and natural processes of population regulation with pesticides used only as therapeutic tools when needed. Emphasis is placed on maximizing the beneficial, desirable ecological processes within farming systems that can maintain weed and pest populations at low, manageable levels. Although agricultural systems are simplified compared to natural ecosystems, there are abundant opportunities to redesign and manage agricultural systems to reduce and eliminate pest outbreaks. No-tillage production systems offer several opportunities to regulate weed and pest populations. One of the biggest advantages to farming without tillage is the maintenance of plant residue on the surface of soils. The soil microclimate under residue avoids temperature extremes and maintains more uniform soil moisture that favors a wide array of organisms. These conditions lead to improvements in soil structure, tilth, nutrient holding capacity, and water-holding capacity as well as biological activity. These improvements to soil physical, chemical, and biological properties can act in a synergistic manner to create a soil that is more similar to that of natural ecosystems. The live and dead plant material associated with use of cover crops in no-tillage systems are particularly suited to natural suppression of weeds and pests. Generally, a more diverse biological and physical environment at the surface of soils such as that associated with cover crops offers opportunities for regulating and minimizing pest populations. Proc. XXVI IHC – Sustainability of Horticultural Systems Eds. L. Bertschinger and J.D. Anderson Acta Hort. 638, ISHS 2004 Publication supported by Can. Int. Dev. Agency (CIDA)