Submitted to: International Institute For Beet Research Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 26, 2003
Publication Date: August 20, 2003
Citation: KAFFKA, S.R., LEWELLEN, R.T., WINTERMANTEL, W.M. BEET CURLY TOP VIRUS, INSECTICIDES AND PLANT RESISTANCE. INTERNATIONAL INSTITUTE FOR BEET RESEARCH PROCEEDINGS. 2003. p. 289-293. Technical Abstract: Beet curly top virus (BCTV), a Gemini virus, remains a problem for farmers in the San Joaquin Valley of California. It is spread by the beet leaf hopper (Circulifer tenellus Baker), which has become naturalized. Recent dependence on non-tolerant sugar beet cultivars has led to increased concern about the potential for a BCTV epidemic, particularly in overwintered crops, which are planted when conditions for infection are greatest. Three trials were carried out in successive years in the western San Joaquin Valley to test the effects of alternative insecticides for control of BCTV on susceptible and tolerant sugar beet cultivars. Two rates of imidicloprid applied as a seed treatment (45 g and 90 g a.i. per 100,000 seeds) were compared to the current standard treatment of phorate applied to soil at 83.8 g a.i. per 1000 m of row, and an untreated control. In the third trial, clothianidan was also used at the rate of 15 g a.i. per 100,000 seeds. Cultivars ranged in tolerance from the most tolerant line available to the most susceptible cultivar ever observed. In the third trial, different planting dates were also compared. Natural BCTV infection occurred in all three years. Sugar beet root and sugar yields declined linearly with increasing rates of infection. Yields declined because roots were significantly smaller with the non-tolerant cultivar and root populations were reduced by plant loss. Sugar percentage was unaffected by treatments, but differed by cultivar. Imidicloprid and phorate provided similar levels of protection to plants, but were not able to prevent large yield losses among susceptible cultivars when infection occurred early in crop development. Plant resistance provided more effective protection than systemic insecticides.