The impact of plant age and genetics on curly top disease development in modern sugarbeet varieties

William M. Wintermantel, Stephen R. Kaffka, Arturo A. Cortez
2005 American Society of Sugarbeet Technologist   unpublished
Performance of current California adapted sugarbeet varieties, which have little resistance to curly top disease, caused by Beet curly top virus (BCTV), were compared with some of the most tolerant (Inter-mountain West adapted) and susceptible varieties available for effect of infection on disease severity and plant weight. Field studies conducted in the 1970s demonstrated that sugarbeet plants were more susceptible and losses more severe when seedlings were infected by BCTV, but less severe
more » ... but less severe when plants were larger at the time of infection (Duffus and Skoyen, 1977). To evaluate more precisely the relationship between age at infection and yield loss in modem varieties which were not bred for curly top reesistance, individual sugarbeet plants were inoculated with 20 viruliferous beet leafhoppers (Circul(fer tenellus) each, when plants had either 2, 4 or 6 true leaves, and maintained in a greenhouse for 6 weeks. When plants were inoculated at the 2 leaf stage, all varieties became severely stunted with high disease ratings and similar rates of symptom development, regardless of tolerance or susceptibility of the variety. Plants inoculated at 4 and 6 leaf stages exhibited increasing separation between tolerant and susceptible phenotypes, with highly tolerant varieties performing well with low disease ratings and slower symptom development relative to susceptible varieties. California varieties performed only slightly better than the susceptible control line, Seedex Monohikari. At the conclusion of experiments, soil was carefully removed from beet roots by washing, and total plant biomass was determined. All varieties were severely stunted when inoculated at the two leaf stage, as indicated by individual plant weight. As plants achieved larger size prior to infection, the effect of curly top on total weight was diminished. Results from greenhouse trials matched those from field trials conducted under heavy curly top pressure.
doi:10.5274/assbt.2005.53 fatcat:vto6pabqdzd3pmr5nasu47hrxy