Submitted to: Society of Nematologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/12/2003
Publication Date: 9/20/2003
Citation: ROBINSON, A.F., AKRIDGE, R., BRADFORD, J.M., GAZAWAY, W.S., MCGAWLEY, E.C., YOUNG, L.D. NEMATODE SURVIVAL MASKS EXPRESSION OF RESISTANCE OF COTTON TO ROTYLENCHULUS RENIFORMIS IN FIELD EXPERIMENTS IN FOUR STATES. JOURNAL OF NEMATOLOGY. 2003. V. 35: ABSTRACT P. 360.
Technical Abstract: Rotylenchulus reniformis is considered the major nematode problem of Upland cotton (Gossypium hirsutum) in Alabama, Mississippi, Louisiana, and the Texas Lower Rio Grande Valley. Because no known G. hirsutum genotypes are resistant to R. reniformis, several breeding projects are underway to introgress resistance into G. hirsutum from other species. Until recently, the level of resistance in such accessions has been measured only in pot experiments. Surprisingly, the first field experiment, conducted at a South Texas site in 2001 showed resistance to be almost entirely suppressed and data from supplemental micro plot and growth chamber experiments indicated some soil factor other than nematode origin was responsible. Therefore, in 2002, the hypothesis that resistance suppression was site-independent was tested by planting nine resistant accessions of G. barbadense, G. arboretum, G. herbaceum, and G. longicalyx in parallel experiments in infested fields in Alabama, Mississippi, Louisiana, and Texas. Root and nematode population densities in soil were measured at harvest at 15-cm increments from the soil surface to 105 cm deep. Resistant accessions did not suppress nematode population in the soil adequately at any site. However, population densities at harvest in soil samples from fallow areas were 29-44% of those under the susceptible control, and when nematode densities under fallow were subtracted from those under resistant accessions, the relative levels of population suppression were similar to those in pot and microplot experiments, indicating resistance was expressed in the field but masked by survival.