Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: June 8, 1999
Publication Date: December 15, 1999
Citation: Timper, P. 1999. Effect of crop rotation and nematicide use on abundance of Pasteuria penetrans [abstract]. Journal of Nematology. 31:575. Technical Abstract: The objective of this study was to determine the effect of rotation and nematicide use on abundance of Pasteuria penetrans, an obligate parasite of nematodes. An experiment was initiated in 1991 with the main plot treatments being peanut following 2 years of either bahiagrass, corn, or cotton; and continuous peanut, corn, and cotton. The subplots were either treated at-plant with nematicide (aldicarb or ethoprop) or untreated (control). There were four and 12 replicate plots for the continuous and rotated crop sequences, respectively. The field site contained an unknown level and distribution of P. penetrans prior to the start of the experiment. Because spores of P. penetrans were frequently found on juveniles of Meloidogyne arenaria, this nematode was considered the primary host for the parasite. In July 1998, soil was collected from each plot and a subsample (100 cm3) was assayed for P. penetrans spores. Greenhouse- cultured M. arenaria juveniles were utilized as assay nematodes. The mean number of spores acquired by assay nematodes after being shaken in a soil: water slurry for 24 hours was used to estimate abundance of P. penetrans. The number of spores per assay nematode was highest in the continuous peanut sequence (22), intermediate in the peanut-bahiagrass sequence (13), low in the peanut-corn sequence (2), and very low in all other sequences (<1). Abundance of spores was similar in the nematicide-treated and untreated plots. When the soil from each cropping sequence was tested in the greenhouse for reproduction of M. arenaria on peanut, there was a negative correlation between the number of nematode eggs produced and the abundance of P. penetrans spores detected [log(eggs)=4.2-0.048(spores), P=0.006, R=0.59].