Field experiments were carried out during two growing seasons at Adnan Menderes University, Faculty of Agriculture, in Aydın-Turkey to evaluate the weed control efficacy of olive processing waste (OPW) in okra, faba bean, and onion. OPW was incorporated into the soil prior to seeding at 10, 20, 30, and 40 tons (t)/ha. Non-treated plots and plots treated with trifluralin in okra and pendimethalin in faba bean and onion were used for comparison. OPW suppressed common purslane, redroot pigweed, and junglerice in okra; littleseed canarygrass, annual bluegrass, wild chamomile, and shepherd's-purse in faba bean and onion. OPW was in most cases equally as effective as soil herbicides; however, 10 t/ha provided sometimes lower efficacy than herbicides. OPW had no negative effects on okra and faba bean, while onion was negatively affected by doses over 30 t/ha. Overall, OPW can be applied at 10 to 20 t/ha doses for weed control with adequate crop safety.

Nomenclature: Pendimethalin; trifluralin; annual bluegrass, Poa annua L.; common purslane, Portulaca oleracea L.; junglerice, Echinochloa colona (L.) Link.; littleseed canarygrass, Phalaris minor Retz.; redroot pigweed, Amaranthus retroflexus L.; shepherd's-purse, Capsella bursa-pastoris (L.) Medik.; wild chamomile, Matricaria chamomilla L.; faba bean, Vicia faba L.; okra, Abelmoschus esculentus (L.) Moench; onion, Allium cepa L.; olive, Olea europaea L.