Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: Comparisons of Soil and Seed Applied Systemic Insecticides to Control Beet Curly Top Virus in the San Joaquin Valley.

Authors
item Kaffka, Steven - UC, CALIF., DAVIS
item Wintermantel, William
item Lewellen, Robert

Submitted to: Journal of Sugarbeet Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 16, 2002
Publication Date: N/A

Interpretive Summary: Beet curly top virus (BCTV) remains a problem for farmers in the San Joaquin Valley of California. It is spread by the beet leaf hopper, a vector common in California. Recent dependence on sugarbeet cultivars that do not have tolerance for this virus has led to increased concern about the potential for a BCTV epidemic. Two trials were carried out in successive years in the western San Joaquin Valley to test the effects of alternative protective insecticides for control of BCTV on susceptible and tolerant (resistant) sugar beet cultivars. Two rates of imidicloprid insecticide 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 1000m of row, and an untreated control. Natural BCTV infection occurred in both years, but the second trial took place during a major beet leafhopper population increase, and infection occurred much earlier in crop development. Sugar beet root and sugar yields declined linearly as infection increased. Yields declined because roots were significantly smaller with the non-tolerant cultivar. Sugar percentage was unaffected by insecticide treatments, but differed by cultivar. Both Imidicloprid and phorate provided similar levels of protection to plants, but were not able to prevent large yield losses among susceptible cultivars. Plant resistance provided more protection than systemic insecticides. Changes in land use in the San Joaquin Valley combined with recent adoption of high yielding but non-tolerant cultivars threaten the viability of sugar beet production in affected areas.

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 in the state. Recent dependence on non-tolerant sugarbeet cultivars has led to increased concern about the potential for a BCTV epidemic. Two trials were carried out in successive years in the western San Joaquin Valley to test the effects of alternative protective insecticides for control of BCTV on susceptible and tolerant (resistant) sugar beet cultivars. Two rates of imidicloprid insecticide 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 1000m of row, and an untreated control. Natural BCTV infection occurred in both years, but the second trial took place during a major beet leafhopper population increase, and infection occurred much earlier in crop development. Sugar beet root and sugar yields declined linearly with increasing rates of infection (r2=0.856). Yields declined because roots were significantly smaller with the non-tolerant cultivar. Sugar percentage was unaffected by insecticide 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. Plant resistance provided more protection than systemic insecticides. Changes in land use in the San Joaquin Valley combined with recent adoption of high yielding but non-tolerant cultivars threaten the viability of sugar beet production in affected areas.

Last Modified: 8/22/2014
Footer Content Back to Top of Page