It is known that high N doses, N/K imbalances, and frequent irrigation favor verticillium wilt. The influence of fertilization and its interaction with the frequency of irrigation on the development of Verticillium wilt of olive (VWO) has been evaluated. A split-split-plot design in microplots with two naturally infested soils of different texture was established for studying three fertilization treatments (NO3Ca, N-P-K and without fertilization), plus two irrigation frequencies (daily and deficit). The treatments were applied by means of fertigation, evaluating the susceptible cultivar Picual. Final disease incidence in plants subjected to NO3Ca-daily treatment was 100% regardless soil texture. However, final mortality in these plants was 37% and 85.2% in clay and sandy loam soils, respectively. As well, the area under the disease progress curve values were significantly higher (49.1%) in plants subjected to NO3Ca fertilization compared to those not fertilized or fertilized with N-P-K when plants grown in clay soil. This value in the sandy loam soil was significantly higher in the NO3Ca-daily irrigation treatment (94.3%), followed by the N-P-K-daily treatment (61.1%) which also was significantly higher than the unfertilized-daily, N-deficit and NPK-deficit treatments (37.8, 42.6 and 44.9 %, respectively). The plants submitted to unfertilized-deficit treatment reached the lowest value 9.6%. In this work it can be concluded that the application of fertilizer or the application of fertilizer with daily frequency irrigations in naturally infested soils increases the development of VWO in 'Picual'.

This paper presents a study of a field trial experiment at olive orchard irrigated by runoff harvesting system under a dry climate which was carried out on 5-year-old olive trees (Olea europaea. L, cv. Barnea) in the middle of Negev desert, starting right after the floods, onwards during the summer growing season. The beginning of the experiment occurred after 2 years with little rain and no run-off events. The olive trees were under severe drought stress when we first initiated controlled flooding in 2017. In the second research year (2018), a massive natural flood had occurred at the end of April. Results show that the water distribution within the soil was highly inhomogeneous even under flood conditions. Soil water loss rate, due to transpiration was mainly correlated with the total amount of soil water and not atmospheric conditions. The relative root water uptake from shallow soil layers (0.3-1.5m) gradually reduced along the season, while the relative water uptake from the deeper layers (1.5-4m) became more pronounced.