Abstract
Four water stresses, 0.3, 4, 8, 12 bar, were used to check their effect on Verticillium wilt in olive. Results showed that the highest effect and percent of the affected branches was associated with first water stress treatment that is significantly different from other treatments in both readings. Second stress treatment (0.13 and 14.97%) for the first reading respectively came second. The third and fourth stress treatments did not differ significantly in their severity with the first reading but they differ significantly in the second reading and they also differ significantly in their percent severity of the affected branched in both readings. The intervention effect of the two olive cultivars (Nibali and Sorani) and their contamination coefficients showed significant increase in the Nibali cultivar in its severity and percent of the affected branches in comparison with Sorani cultivar in the first reading (0.26%, 29.80%) respectively. No symptoms were shown on non–contaminated both of the two cultivars of olive seedlings. The first water stress treatment showed the highest effect and percent of the affected branches with the contaminated Nibali cultivar(0.75%, 65.58%) that were significantly different from other treatments and for both readings respectively. This was followed by severity incidence and percent of the affected branches with the second water stress treatment (0.63%, 50.05%) respectively and was not significantly different from the first water treatment for Sorani cultivar (the contaminated) in severity and for both readings. The third and fourth stress treatments were not different from each other in the Nibali cultivar (the contaminated) and not significantly different from the second and third water stress treatment for Sorani cultivar (the contaminated) in the first reading. However, they were different in the second reading as related to severity and percent of the affected branches. The less was in the fourth stress treatment and reached (0.18%, 6.26%) in the Nibali cultivar and (0.19%, 9.72%) in the Sorani cultivar. The study concluded that the fourth stress treatment is the best and caused a reduction of (37.57% and 59.32%) in the Nibali cultivar and for both readings, respectively.
