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Applying Pesticides With Center-Pivot Irrigation

E.J. Buffington and, S.K. McDonald (June, 2006)

Summary

The pros and cons of applying pesticides in this manner are the subject of constant debate, particularly in comparison with aerial application. Among the advantages for center-pivot applications are reduced application costs, uniformity of application, timeliness of application, possible reduced operator hazard, possible reduced chemical requirements, and improved canopy penetration. The major disadvantage of this application method is the potential hazard posed to groundwater by the backflow of pesticides into the well when the irrigation pump is shut off. Another problem is water flowing into the nurse tank, which can occur if the injection pump is shut off and the irrigation pump continues to run. This can cause overflows and chemical spills. If the irrigation pump stops and the injector continues, an overapplication results, possibly causing crop damage and environmental contamination. Finally, excess watering is common near the pivot and at the end gun, which can lead to overapplication, deep leaching and runoff of pesticides in these two areas. Improperly adjusted end guns or windy weather also can result in the application of pesticides to adjacent Crops and noncrop areas. This fact sheet explains how these problems are minimized if the application and safety procedures are followed closely.