Effects of soil fumigants and aldicarb on nematodes, tuber quality, and yield in potato.

Efficacy of the fumigants ethylene dibromide (EDB), EDB + chloropicrin, and 1,3-dichloropropene (1,3-D) applied with one or three chisels per row, singly or in combination with aldicarb, was evaluated in 1982 and 1983 on potato (Solanum tuberosum) cultivars Atlantic and Sebago for control of several nematodes, including Belonolaimus longicaudatus, Meloidogyne incognita, and trichodorids. Generally, nematode populations were lowest following application of fumigants with three chisels per row, following EDB or EDB + chloropicrin, and when fumigants were applied in combination with aldicarb. These treatment combinations also resulted in highest yields in 1983. Cosmetic appearance of tubers was improved (P </= 0.05) by aldicarb in 1982. Both bacterial wilt and nematodes reduced yield; however, stepwise multiple regression analysis estimated that the greater loss in yield was associated with bacterial wilt, especially in Atlantic during 1983. Economic analysis showed that addition of aldicarb to all 1,3-D treatments increased profits. The increase was greater in Atlantic than in Sebago. Triple-chisel fumigation produced greater profits than single-chisel fumigation in Atlantic during both years and in Sebago in 1982.