Effects of Soil Type on the Reproductive Potential of Rotylenchulus reniformis on Cotton

The reniform nematode, Rotylenchulus reniformis, is the most damaging nematode pathogen of cotton in Alabama. Trials to determine the reproductive potential of R. reniformis as affected by soil type were conducted in both microplot and greenhouse settings in 2008 – 2010. The soil types evaluated were a Dothan sandy loam (S-S-C  = 57-28-15), a Decatur silt loam (S-S-C = 23-49-28), a Hartsells fine sandy loam (S-S-C = 51-38-11), a Ruston very fine sandy loam (S-S-C = 59-33-8), a Lloyd loam (52-23-25 S-S-C), and a Vaiden clay (S-S-C = 5-42-53).  Within the microplot trials, populations of R. reniformis were significantly different between soils and between irrigated and non-irrigated plots of the same soil. However, reproductive factors differed very little either between soils or between irrigated and non-irrigated plots of the same soil. For the greenhouse trials, reniform nematode populations were again significantly different between soils and differing initial populations resulted in significant changes in shoot/root ratio both within soils and between soils. Shoot/root ratios were not significantly different at any initial population (PI) in the Decatur silt loam and the Ruston very fine sandy loam, but decreased significantly at a PI of 1000 or greater for the Lloyd loam, 2000 or greater for the Vaiden clay and 5000 or greater for the Hartsells fine sandy loam and the Dothan sandy loam. These results indicate that differences in soil growth potential have a direct effect on the nematode/cotton interaction.