Effects of varying planting dates and tillage systems on reniform nematode and browntop millet populations in cotton

Authors: Stetina, Salliana - Sally; Molin, William; Pettigrew, William

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/9/2010
Publication Date: 12/27/2010
Citation: Stetina, S.R., Molin, W.T., Pettigrew, W.T. 2010. Effects of varying planting dates and tillage systems on reniform nematode and browntop millet populations in cotton. Plant Health Progress. doi:10.1094/php-2010-1227-01-RS.

Interpretive Summary: Alternative cotton cropping practices, including early planting and reduced soil tillage, have the potential to affect other species that coexist with cotton, including pests. Pests of cotton, common to the Mid South, examined in this study were reniform nematode, a tiny worm that feeds on cotton roots causing yield loss, and browntop millet, a grass that can rapidly develop late in the growing season causing yield loss and quality reduction. We measured how these two pest species responded to planting date (early planting around April 1 or normal planting around May 1) and tillage (conventional tillage where the soil is thoroughly worked prior to planting or minimum tillage where the only soil disturbed is that necessary to incorporate the seeds) using four commercial cotton varieties. There were no treatment effects on reniform nematode populations. We did not find any treatment that reduced the population of reniform nematode, but neither did we find any treatment that favored development of large populations of the nematode. More browntop millet developed when plots were established early or when minimum tillage was used. The traditional cotton production system, planting into tilled soil in early May, appears to provide better suppression of this weed. Factors other than nematode management should be given priority when selecting planting date and tillage practices. Management of browntop millet is favored by the traditional cotton production practices. Additional studies are needed to assess the impact of these alternative cropping practices on other weeds, diseases, and insects.

Technical Abstract: Cropping practices that reduce damage from reniform nematode (Rotylenchulus reniformis) and browntop millet (Urochlora ramosa) may be useful as part of a management program to minimize losses in cotton (Gossypium hirsutum) in the Mid South. The impacts of early planting dates and reduced tillage systems on populations of these pests were investigated from 2005 to 2007. Planting dates (April 1 or May 1) and tillage systems (conventional or minimum-tillage) were evaluated on four commercial cotton cultivars in a field study at Stoneville, MS using a randomized complete block design with a split plot treatment arrangement. Despite some variability in early-season root infection, reniform nematode soil populations were not affected by either planting date or tillage treatments. Thus, it appears that neither of the tillage practices nor the alterations in planting date examined in this study should be recommended for inclusion in a reniform nematode management program at this time. Mid- and late-season browntop millet pressure was greater in minimally tilled plots and in plots planted early. More effective season-long suppression of browntop millet appears to be associated with the traditional planting date and conventional tillage system, so these production practices could benefit producers who need to manage this weed.