Submitted to: Journal of Agricultural and Urban Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2014
Publication Date: 11/4/2014
Citation: Jackson, D.M., Ling, K., Simmons, A.M., Harrison Jr, H.F. 2014. Management of sweet potato leaf curl virus in sweetpotatoes using insecticides. Journal of Agricultural and Urban Entomology. 30:82-95.
Interpretive Summary: Sweet potato leaf curl virus, a disease transmitted by the sweetpotato whitefly, can severely reduce yields of commercial sweetpotato varieties. In this study, ARS scientists at Charleston, SC, investigated reducing the incidence of this disease in sweetpotato fields by spraying insecticides to control whiteflies. Spraying insecticides weekly or twice a week had little impact on whitefly populations in small sweetpotato plots. Even with intensive sprays, only about one-half of the plots could be protected from sweet potato leaf curl virus, indicating that insecticide management of this disease has limited value. Results of this study provide valuable information to entomologists and state extension personnel working to manage whitefly infestations and disease incidence in sweetpotato.
Technical Abstract: Sweetpotato leaf curl virus (SPLCV), which is transmitted by the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), can severely affect yields of commercial sweetpotatoes, Ipomoea batatas (L.) Lam. (Convolvulaceae). This virus occurs every year at the U.S. Vegetable Laboratory (USVL), Charleston, S.C. In 2010 and 2011, small plots of virus-tested (negative for ‘SPLCV) Beauregard’ sweetpotato were grown at the USVL to see if they could be protected from SPLCV using insecticides. In 2010, six replications were planted in double-row plots of ten plants each. The two treatments were nonsprayed plots and plots sprayed twice weekly with imidacloprid (Provado 1.6F at 2.0 mls/gallon). A row of SPLCV-infected sweetpotato genotype W-258 was planted between the treatment plots to serve as a source of this virus. A similar test was performed in 2011, except that the plots were sprayed only once a week, and a rotation of four insecticides was used. These insecticides were Provado 1.6F (imidacloprid at 2.0 mls/gallon), Knack (pyriproxyfen at 3.0 ml/liter), Assail 30SG (acetamiprid at 1.3 grams/liter), and Endeavor 50WG (pymetrozine at 0.15 ml/liter). Yellow sticky traps were placed in each plot to monitor for whiteflies. Leaf samples were taken every other week to check for SPLCV using real-time PCR. Over the 2-year period, there were significantly fewer whiteflies on sticky cards in the sprayed treatment for only 2 of the 36 weekly samples, indicating that insecticides were largely ineffective in reducing whitefly populations in these plots. By the end of both years, all of the nonsprayed plots were infected with SPLCV. However, only about one-half of the sprayed plots were infected with SPLCV. Although, the overall incidence of SPLCV was reduced in the sprayed plots, the use of insecticides is not a recommended option for managing this disease in sweetpotato fields. It was also determined that although large populations of the potato leafhopper, Empoasca fabae (Harris) found in the sweetpotato fields tested positive for SPLCV, they were unable to transmit it to sweetpotatoes. True sweetpotato seeds from virus-infected plants also did not produce virus-infected seedlings.