Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2011
Publication Date: 7/5/2011
Citation: Nansen, C., Vaughn, K., Xue, Y., Rush, C., Workneh, F., Goolsby, J., Troxclair, N., Anciso, J., Gregory, A., Holman, D., Hammond, A., Mirkov, E., Tantravahi, P., Martini, X. 2011. A decision-support tool to predict spray deposition of insecticides in commercial potato fields and its implications for their performance. Journal of Economic Entomology. 104(4):1138-1145. Interpretive Summary: Application of insecticides for control of the potato psyllid in commercial potatoes was studied in three locations in Texas. The authors documented the spray pattern on the potato leaf when applied by ground using a tractor and by air using a plane. Weather variables including temperature, humidity, rainfall and wind were measured at the time of application. The results showed that the actual amount of insecticide on the leaves varied greatly using both methods, especially when applied by airplane. A decision support tool was developed and placed on the web to help growers decide the optimum conditions for spraying potato fields. The results are discussed in terms of developing the most effective integrated pest management program for the potato psyllid.
Technical Abstract: In conventional and most IPM programs, application of insecticides continues to be the most important responsive pest control tactic. For both immediate and long-term optimization and sustainability of insecticide applications, it is paramount to study the factors affecting the performance of insecticides when applied in commercial fields. In this study, a large field study was conducted in three commercial potato fields in Texas, and we examined the correlation between spray deposition (quantified on the basis of water sensitive spray cards) and a series of explanatory variables (including: weather data, plant height, and application method) during 14 commercial insecticide spray applications. We developed a highly accurate multi-regression model, which has been made available as a user-friendly decision-support tool that can be accessed via the internet (http://pilcc.tamu.edu:8080/PILCC). This decision-support tool shows how even small variations in abiotic conditions can cause a dramatic difference in spray deposition. Controlled experiments with potato psyllids on potato leaflets were conducted with different insecticides to characterize the relationship between insecticide spray deposition and its performance. The main conclusions from this study are that actual spray deposition in commercial fields often varies 30-100-fold within fields and frequently are as low as 5%, especially when applied by air. Optimization of insecticide spray deposition should be considered a fundamental pillar of successful IPM programs to increase efficiency of sprays (and therefore reduce production costs) and to reduce risk of resistance development in target pest populations.