Predicting crop damage from nematodes relies on knowledge of the life cycle, population changes over time, the crop, cropping system, soil texture, and soil water relations. Action thresholds ( the decision to treat with a nematicide) include economic factors: cost of nematicides and application, value of the crop, and potential for profit. Thresholds for treatment differ from region to region because of variation in sampling, efficiency of extraction, local climate, cropping systems, and varieties of cotton.