Damage function and economic threshold for Belonolaimus longicaudatus on potato

Belonolaimus longicaudatus has long been recognized as a pathogen of potato (Solanum tuberosum). However, a damage function relating expected yield of potato to population densities of B. longicaudatus at planting has not bee n derived, and the economic threshold for nematicide application is unknown . The objectives of this study were to derive the damage function of B. lon gicaudatus on potato and to calculate the economic threshold population den sity. The damage function data for B. longicaudatus on potato were obtained from an ongoing field study to evaluate cropping systems and nematode mana gement practices. Soil samples were collected from experimental field plots , and nematodes were extracted from a 130-cm(3) subsample with a centrifuga l-flotation method. A damage function was derived by linear regression of p otato yield on nematode population density at planting. Based on this deriv ed damage function and published potato prices, the economic threshold for nematicide application was calculated at 2 to 3 B. longicaudatus/130 cm(3) of soil, which was near the detection threshold based on methodology used i n this study.