engleski

Screening of Beta PIs from the NPGS for resistance to Cercospora Leaf Spot at multiple locations, 1997

Thirty-five PIs (Garden Beet, Sugar Beet, Leaf Beet, Fodder Beet, and wild beet) were screened at three locations: 1) an artificially produced epiphytotic (Ruppel, E.G., and J.O. Gaskill. 1971. Techniques for evaluating sugarbeet for resistance to Cercospora beticola in the field. J. Am. Soc. Sugar Beet Technol. 16: 384-389) in Fort Collins, CO ; 2) an artificially produced epiphytotic in Osijek, Croatia ; and 3) a naturally occurring epiphytotic in Osijek, Croatia. Randomized complete-block designs, with two replications were used to evaluate germplasm. Internal controls included a highly susceptible synthetic check and a resistant hybrid check, FC (504x502/2) x SP6322-0. Two-row plots were 4 m long, with 56 cm between rows and 20- to 25-cm within-row spacing. The artificially inoculated nurseries were inoculated twice, on 13 and 23 June in Osijek, and on 27 June and 8 July in Fort Collins. Visual evaluations on a scale from 0 (no disease) to 10 (plant dead) of PIs in the natural and artificial Cercospora epiphytotics were made in Croatia on 8, 18, and 28 Aug. Evaluations in Fort Collins were made on 2, 9, and 16 Sept, with the peak of the epidemic occurring on or about the last date. This project was supported by the USDA-ARS NPGS and USDA/FAS/RSED grant HR02. In Fort Collins, the 1997 leaf spot epidemic progressed rather slowly at first, but rapidly became quite severe by late August to early September. At our third evaluation, means of the resistant and susceptible internal controls were 3.7 and 7.3, respectively, across all trials in the nursery. An analysis of variance (PROC ANOVA - SAS) on the disease indices (visual evaluation scores) determined that there were significant differences among entries (P=0.05) on all three dates at all three locations. An LSD was generated for mean separations. Although the variation was higher in Osijek, some entries performed very differently at the different locations.

sugarbeet; cercospora

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