Submitted to: Idaho Winter Commodity School Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/13/2005
Publication Date: 8/1/2005
Citation: Strausbaugh, C.A., Gallian, J.J., Camp, S., Foote, P., Gillen, A.M. 2005. Managing curly top. In: Proceedings of the University of Idaho 2005 Winter Commodity Schools. Snake River Sugarbeet Conference, January 14, 2005, Nampa, Idaho. 2005 CDROM. Interpretive Summary: Beet curly top virus (BCTV) on sugarbeets is widespread throughout the western United States. The virus results in dwarfed plants with distorted rolled leaves and yield loss. Plants of susceptible cultivars infected early in the season may even die. The primary means of disease control is the use of disease resistant cultivars. We conducted this study to establish that disease resistance identified in an artificially inoculated nursery correlates with disease resistance and yield under commercial growing conditions. To establish this relationship, 29 commercial hybrids were visually evaluated for resistance to BCTV in both a disease nursery and under commercial growing conditions. Data analysis of disease ratings indicated there was a correlation between the two studies. These results indicate that disease resistance identified in nurseries is reflective of cultivar performance under commercial growing conditions.
Technical Abstract: Commercial sugarbeet hybrids were evaluated for disease resistance to Beet curly top virus (BCTV) to establish that disease ratings taken in an artificially inoculated nursery translate to improved disease resistance and yield in commercial fields exposed to natural epiphytotics. To establish this relationship, 29 hybrids were planted in a nursery in Kimberly, ID and a commercial sprinkler-irrigated field in Nampa, ID in 2004. Plants were evaluated for BCTV using a Disease Index (DI) scale of 0 to 9 (no symptoms to dead). The moderately severe epiphytotic in Nampa resulted in uniform disease pressure and significant differences among hybrids for DI, root yield, sugar content, and estimated recoverable sugar. Nampa disease ratings were positively correlated with (r = 0.913, P < 0.0001) ratings from the nursery. In the commercial field the regression line for estimated recoverable sugar versus DI rating indicated that yield was related to disease severity (r squared = 0.54, P < 0.0001). For each unit increase in DI (increasing susceptibility) there was a decrease of 957.53 lb of recoverable sugar/A. These data confirm results collected in 1992 from a commercial variety trial in Ontario, OR and a curly top nursery. Thus, nurseries can be used to select resistant hybrids, the primary means of defense against BCTV.