Interaction between the Reniform Nematode and Thielaviopsis Basicola on Cotton

Recent research has demonstrated an important interaction between Thielaviopsis basicola, the cause of black root rot, and the root-knot nematode, Meloidogyne incognita (Walker et al., 1998; 1999; 2000). This interaction causes dramatic reductions in early-season growth in producers’ fields and yield reductions of 21 to 44% have been documented in microplot and field research. The interaction increases the damage caused by the two pathogens by increasing the early-season impact from the nematode and extending the damage from black root rot from the seedling stage to a season-long problem. In 2003, a number of producers’ fields were again observed with severe stunting of cotton early in the growing season. Soil samples from two fields indicated that the primary nematode problem in these fields was not the root-knot nematode, but the reniform nematode, Rotylenchulus reniformis. Paired plots were established to examine