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For efficient integrated management of verticillium wilt in olive (VWO), it is important to establish whether irrigation treatments (with Verticillium dahliae‐free water) that mitigate the disease in V. dahliae‐infested soil, also reduce the levels of more and less persistent propagules of the pathogen in the soil. Effects of irrigation on VWO and V. dahliae propagules were evaluated under natural environmental conditions. Potted plants were irrigated (pathogen‐free water) to two ranges of soil water content (RWC; high and low) at three surface drip‐irrigation frequencies (daily, weekly, and daily during some periods and otherwise weekly). VWO and total inoculum density (ID), density of less persistent micropropagules (MpD) and more persistent sclerotia in wet soil (SwD), and sclerotia density for air‐dried soil (SdD) were monitored. A logistic model (multiple sigmoid) of disease incidence revealed the lowest parameter values in treatments irrigated daily. Daily frequency of irrigation showed significantly lower disease incidence (39.2%) and disease intensity index (43.9%) and MpD (88.0%) values as areas compared with other frequencies, regardless of the RWC. High RWC significantly reduced (70.8–84.9%) ID, SwD and SdD as areas, but significantly increased (18.0%) the incidence of infected plants (IIP), regardless of the irrigation frequency. The disease incidence was not correlated with temperature. Daily irrigation to low RWC mitigated the VWO and the IIP, kept soil to the lowest MpD and resulted in the lowest SdD level at the end of the trial. Results suggested that less persistent propagules could have played a part in the disease development.

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The measurement of bulk net assimilation (A) in fruit tree species is hindered by the need for sophisticated and complex instrumentation. The aim of this study is to present a simple alternative for estimating A from sap flow measurements and meteorological records. The proposed method was tested in a mature hedgerow olive orchard of 22.2 ha. Within the orchard, an irrigation experiment was established in a small plot including three treatments: a full irrigated control (CI), regulated deficit irrigation (DI) and a treatment mimicking customary orchard irrigation management (FI). Determinations of sap flow, water potential (Ψ) and trunk diameter variations (TDV) were conducted in the three treatments for three years. Also, measurements of net ecosystem exchange (NEE) were performed with an eddy covariance system in the centre of the orchard for the first season. The validity of the method was supported by the fact that estimates of A were consistent with both the measured values of NEE and published data regarding the same species under similar environmental and management conditions. Also, differences in A between irrigation treatments were generally in agreement with irrigation applied, transpiration (E p ), Ψ and TDV. It is concluded that the proposed sap flow-based method represents a user-friendly approach to estimate A at the canopy-level with potential to study the effects of deficit irrigation on biomass accumulation.

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