Effects of subsoiling and nematicides on Hoplolaimus columbus populations and cotton yield.

Subsoiling to a depth of 35 cm under the planting row for 3 consecutive years increased annual yields of seed cotton by 50 to 200%. Annual subsoiling was essential for maximum yields. The application of a nematicide, 1,2-dibromo-3-chloropropane (DBCP) or aldicarb, reduced the population of Hoplolaimus columbus but did not increase seed-cotton yields over subsoiling alone. Subsoiling reduced H. columbus in the top 20 cm of soil since the treatment favored deeper penetration by much of the root syslem and, consequently, less root colonization of the upper soil zone.