Technical Abstract: Fumigation for nematode management in irrigated potato production systems of Idaho is widely practiced. Spatially uniform fumigation with large scale soil injection equipment is the only labeled application method for 1,3-dichloropropene. Plant-parasitic nematode species exhibit spatially variable population densities that provide an opportunity to practice site-specific fumigation to reduce chemical usage and production costs. From 2002 through 2008, 62 commercial potato fields in eastern Idaho were field tested using geo-referenced grid soil sampling for plant-parasitic nematode population densities. In total, 4,030 grid samples were collected representing nearly 3200 ha of commercial potato production. Collectively, 73% of the grid samples had Columbia Root Knot (CRN) (Meloidogyne chitwoodi) densities below the detectable limit. Site-specific fumigation is the practice of varying application rate of fumigant based on nematode population density. Over the past 3 years, 1200 ha of potato production has been site-specific fumigated for CRN nematode control in eastern Idaho. On average this practice has resulted in a 30% reduction in chemical usage and production cost savings of $180/ha when 1,3-dichloropropene is used as the sole-source of nematode suppression. Further reductions in usage of 1,3-dichloropropene can exceed 50% if used in combination with another nonfumigant nematicide such as oxamyl. This combination approach can have production cost savings that exceed $200/ha. Based on farm-gate receipts and USDA inspections provided by potato producers, potato tuber yield and quality have not been adversely affected using site-specific fumigation technology.