POPULAT ION ASSESSMENT AND MANAGEMENT STRATEGIES FOR PLANT-PARASIT IC NEMATODES l

Ferris, H., 1985. Population assessment and management strategies for plant-parasitic nematodes. Agric. Ecosystems Environ., 12: 285--299. Nematodes exhibit aggregative tendencies mediated by food distribution, feeding and reproductive behavior, and survival strategies. Determination of dispersion indices based on population mean and variance allows estimation of the sampling intensity required for prescribed population assessment precision. Critical point models of ex-pected yield loss relative to pre-plant population density allow management decisions on a single season basis. Selection of optimal cropping sequence across several seasons requires further information on the expected multiplication rate of the population on a crop, and the overwinter survivorship of the population. Three critical point models then formulate the basis for a linear programming approach to cropping sequence selec-tion, while allowing flexibility of management through biological and economic moni-toring annually