The effect of irrigation on the abundance of Empoasca vitis (Go ̈ the) populations was
investigated in four vineyards located in northeastern Italy. In two experiments, we compared
leafhopper population densities in plots irrigated (micro-spray irrigation system) or nonirrigated. In
another experiment, we studied the effect of various irrigation systems on E. vitis populations over
two successive seasons. In particular, Þve treatments were compared: control (not irrigated), traditional
drip system, three types of subirrigation varying in distance from the row (40, 135, and 95 cm).
In this vineyard, stem water potential was monitored with a pressure chamber. E. vitis population
densities were affected by irrigation, with higher densities of this pest recorded on irrigated vines.
Highest E. vitis densities were detected in drip irrigation plots compared with nonirrigated plots where
water stress was highest. Moderate water stress (subirrigation plots) was associated with intermediate
leafhopper densities. Implications for integrated pest management are discussed.
