Effects of cultivars, subsoiling, and fumigation on soybean yields and Meloidogyne incognita populations.

Application of 1,2-dibromo-3-chloropropane (DBCP) and subsoiling under the row in Tifton sandy loam heavily infested with Meloidogyne incognita increased yields of four soybean cultivars. These cultivars have levels of resistance to M. incognita as follows: 'Hutton', high; 'Essex', intermediate; and 'Davis' and 'Ransom', low. After growing these four cultivars, sub-soiling, and applying DBCP for 2 years in the same plots, the residual effects of these practices on yield of Davis cultivar and populations of M. incognita were studied. Greatest yields of Davis were obtained on plots previously planted to Hunon and Essex and on plots previously treated with DBCP for 2 years. Residual effects of subsoiling on yield were not significant. Data on nematode populations indicated that some residual effects occurred because of cultivars and nematicides. However, root-knot was suppressed only where DBCP was applied the 2 previous years. Although beneficial residual effects occurred, they were not sufficient for maximum soybean production.