Conventional agricultural systems increase food production per acre but can deplete natural resources and degrade crop and environmental health. By implementing organic farming as an alternative production system, growers may substitute cultural and biological inputs for synthetically-made chemicals and fertilizers that still provide effective pest and disease management.
Many insects—in fact, most insects—on agricultural land are actually beneficial. Beneficial insects prey on the pests whose favorite foods happen to be the cash crops. Different plants attract different insects, so encouraging a diversity of plant species beyond cash crops can shift the balance away from pest insects. Diversity encourages a healthy and resilient system.
In general, improving soil quality and encouraging beneficial organisms will help reduce pest populations and prevent disease. Gypsum, dolomite, and potassium magnesium sulfate can correct plant nutrient deficiencies or imbalances, raise soil pH, leach out excess exchangeable sodium by calcium replacement, and improve soil water infiltration. Beneficial insects such as green lacewing, lady beetle, and syrphid feed on many soft-bodied insect pests such as aphids, mites, whiteflies, thrips, and some beetle larvae.
Growers may also follow these recommendations to reduce problems they may face during the transition period:
• Select land with high nutrient status, good soil structure and low pest and disease pressure if possible.
• In the first year, plant a crop less reliant on nitrogen to offset some problems associated with low soil N.
• Design a crop rotation with pest-resistant leguminous cash or cover crops to supply N (such as fava bean, hairy vetch and crimson clover), reduce pest populations and enhance soil organic matter.
• Select crops (such as buckwheat, dill, oregano, thyme, red cosmos, yarrow, marigold) that attract beneficial organisms (such as lady beetles, spiders, lacewings, arthropods, millipedes, and honey bees) both above the soil surface and underground.
• Routinely incorporate green manure and compost in your cropping system to increase soil organic matter, improve water infiltration and reduce soil erosion.
• Alternate cool-season crops with warm-season crops to interrupt pest and disease cycles.
• Choose reduced or no-cultivation techniques that are practical and economical, such as using a high-residue cultivator and roller-crimper.
• Manipulate planting dates. For example, plant immediately after bed cultivation and/or bed preparation to allow establishment of crop plants before re-growth of weeds and to potentially break insect life cycles.
• Use pest-free stocks and pest and disease resistant crop varieties.
• Scout and trap using insect pheromones.
• Use soil solarization in regions with warm and sunny climate to reduce soil borne pathogens and other pests.
Hogg, B. N., R.L. Bugg, and K.M. Daane. 2011. Attractiveness of common insectary and harvestable floral resources to beneficial insects. Biological Control 56: 76–84.
Hooks, C.R.R., K.-H. Wang, A. Ploeg, R. McSorley. 2010. Using marigold (Tagetes spp.) as a cover crop to protect crops from plant-parasitic nematodes. Applied Soil Ecology 46: 307-320.
Zinati, G.M., 2002. Transition from conventional to organic farming systems: I. Challenges, recommendations and guidelines for pest management. HortTechnology 12:606-610.
Dr. Gladis Zinati
Interim Research Director
Pennsylvania Farm Link, Inc.
Division Chief for Economic Development
PA Department of Agriculture