Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2006
Publication Date: 12/1/2006
Citation: Strausbaugh, C.A., Gillen, A.M., Gallian, J.J., Camp, S., Stander, J.R. 2006. Influence of host resistance and insecticide seed treatments on curly top in sugar beets. Plant Disease. 90(12):1539-1544. Interpretive Summary: Curly top on sugar beets is a considerable problem on a number of important crops in arid growing regions of the western United States. Curly top on sugar beets can be caused by Beet severe curly top virus or a number of other closely related species transmitted by the beet leaf hopper. Curly top almost eliminated the sugar beet industry in southern Idaho until beets with resistance became generally available in 1935. Since that time, host resistance has been the primary means of control for curly top in sugar beets. Some measure of control is also possible through adjustment of planting dates and soil applied systemic insecticides, however more effective control measures would be desirable. Thus, we conducted studies to establish the influence of host resistance and insecticide seed treatments on the control of curly top in sugar beets. Under moderate to heavy infection pressure, Poncho Beta insecticide seed treatment was able to provide acceptable protection from curly top on all hybrids tested. Even sugar beet hybrids highly susceptible to curly top had acceptable levels of curly top at the end of the season and reasonable yield parameters. The Poncho Beta treatment outperformed both Gaucho and untreated check in curly top ratings, root yield, and estimated recoverable sugar based on contrasts. Data presented indicate that “second generation neonicotinoid insecticides” may prove to be a valuable tool in controlling curly top in sugar beets in Idaho. We should continue to improve on host resistance to curly top along with investigating the potential for utilizing seed treatments to supplement host resistance.
Technical Abstract: Curly top on sugarbeets caused by Beet severe curly top virus or closely related strains is a considerable problem in arid growing regions of the western United States. Two insecticide seed treatments, Poncho Beta (60 g ai clothianidin + 8 g ai beta-cyfluthrin/100,000 seed) and Gaucho (45 g ai imidacloprid/100,000 seed), and four sugar beet hybrids varying in curly top resistance were evaluated for their influence on the control of curly top in comparison to untreated checks. Plots were established at two locations in southern Idaho and evaluated for curly top. Moderate to severe curly top due to natural inoculum and leaf hopper infestations occurred at both locations. Untreated, the four hybrids performed as expected with the fewest curly top symptoms on PM21 and the most on Monohikari. Both insecticide treatments lowered curly top ratings compared to the untreated check but Poncho Beta reduced symptoms more than Gaucho during the second and third ratings. Poncho Beta led to increased yield and estimated recoverable sugar across all hybrids at harvest, particularly on the more susceptible hybrids. When considering the yield parameters for only the most resistant hybrids individually, Poncho Beta did not always out perform Gaucho. Poncho Beta provided a level of control that would justify its application as a supplement to host resistance under Idaho conditions.