Approximately 300 ,000 acres of sugar beets are planted in California annually. The most important nematode pest of this crop is the sugar beet cyst nematode, Heterodera schachtii (1 )3. This nematode may cause serious yield losses in all soil types. In contrast, the widespread root-knot nematodes, Meloidogyne incognita and Meloidogyne javanica, are injurious to sugar beets primarily in sandy to sandy loam soils. The soil fumigant D-D (1, 3-dichloropro­ pene and 1, 2-dichloropropane) was used on sugar beet cyst nema­ tode shortly after its introduction in 1943. The effectiveness of D-D and Telone (1, 3-dichloropropene) for control of root-knot nema­ todes on sugar beets was reported in 1958 by Lear and Raski (7). They also noted the complete collapse of sugar beets on untreated soil following the last irrigation of the season and suggested an addi­ tive relationship between root-knot nematodes and root rotting organisms.