|Stetina, Salliana - Sally|
Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2006
Publication Date: 6/1/2006
Citation: Stetina, S.R., Sciumbato, G.L., Blessitt, J.A., Young, L.D. Cotton cultivars tolerant to reniform nematode. Journal of Nematology. 38:294.
Technical Abstract: Thirty-six commercial cotton (Gossypium hirsutum) cultivars were evaluated to identify those that are most tolerant to reniform nematode (Rotylenchulus reniformis) and therefore do not exhibit reduced yield due to this pest. Field trials were conducted for three years at two locations in the Mississippi Delta that were naturally infested with reniform nematode at population levels exceeding the action threshold for Mississippi. Main plots were cultivars and subplots were either not treated or treated with nematicide (1,3-dichloropropene or aldicarb) at recommended rates. Reniform nematode population densities were assessed at planting, midseason, late season, and harvest. Plots were mechanically harvested to determine seed cotton yields. Data from all years and locations were pooled, and tolerant cultivars were identified using one-tailed t-tests (P=0.05). Cultivars for which nematicide significantly reduced the nematode population at either the midseason or late season sampling intervals, but for which yields were not significantly higher due to nematicide application, were judged to be the most tolerant. Only Deltapine 449 BR, Paymaster 1218 BR, and SureGrow 215 BR met these criteria. In addition, tolerance indices [index = (yield of nontreated plot/yield of nematicide-treated plot)*100] were calculated and compared for nine cultivars that showed suppressed nematode populations in nematicide-treated plots at any point during the growing season. Differences of least squares means showed that SureGrow 215 BR's tolerance index of 106.4 was significantly higher than Deltapine 20 B's index of 85.8, though neither cultivar differed from the others evaluated. The three cultivars identified as being tolerant based on the t-tests ranked first (SureGrow 215 BR), second (Paymaster 1218 BR), and fifth (Deltapine 449 BR) with respect to tolerance index. These cultivars may be beneficial to growers because they do not appear to suffer significant yield loss in the presence of reniform nematode.