LAUSR

Abstract Effects of olive cake and olive mill waste water on Orobanche ramosa L. infection to tomato (Lycopersicon esculentum Mill.) were investigated in pot experiments conducted under glasshouse conditions during the spring/summer seasons of the 2016 and 2017. Treatments included the use of olive mill cake, cake extracts or mill waste water. In all experiments, treatments were arranged in a randomized complete block design with four replicates. Soil mulching with olive cake slightly affected total parasite shoot number but reduced its shoot dry weight compared with infested-control. Tomato shoot dry weight in all mulch treatments was not significantly different from that of parasite-infested control but greatly reduced compared with Orobanche-free control. Weekly application of olive cake aqueous extract for 3–6 weeks after tomato transplanting reduced tomato shoots dry weight and shoots number and dry weight of O. ramosa. Other extract treatments stimulated or had no effect on tomato growth or Orobanche infection compared with Orobanche-infested control. Soil-incorporated olive cake reduced tomato shoot and root dry weights at the highest (300 and 400 g per pot) rates used in the summer but rates between 50 and 400 g/pot significantly reduced tomato growth during the spring. All treatments significantly reduced Orobanche shoot number (except the lowest rate) and dry weight compared with Orobanche-infested control. Pre- or post-plant application of olive mill waste water and up to 400ml/pot showed no phytotoxicity on tomato; but lower rates in post-plant application increased crop shoot and root dry weights over parasite-free control. Total shoot number and dry weight of O. ramosa at 400 ml per pot were reduced by 70% and 74% for both parameters, respectively. In conclusion, olive mill waste water was more selective and effective against O. ramosa than olive cake and of a high potential use for parasite control in tomato.