Effect of Olive-Mill Wastewater Application, Organo-Mineral Fertilization, and Transplanting Date on the Control of Phelipanche ramosa in Open-Field Processing Tomato Crops

Phelipanche ramosa (L) Pomel is a root holoparasitic weed for many crops, particularly for the processing tomato in Italy. In order to integrate the use of chemical methods to control P. ramosa (L.), there has been an increased effort to research alternative methods using natural compounds. In this regard, two experimental trials were set up in an open field in Foggia (southern Italy) during the 2016 spring–summer seasons. The first trial compared two tomato seedling transplanting dates to evaluate the effects on emerged shoots of P. ramosa. The second trial compared six organic compounds added to the soil to control P. ramosa: olive-mill wastewater and five commercial products (Allyl Isothiocyanate®, Alfaplus®, Radicon®, Rhizosum Max®, and Kendal Nem®). An untreated control was also included. The numbers of P. ramosa emerged shoots (branched plants) were significantly lower for the late tomato seedling transplanting date than for the earlier one. All of the organic products tested that were applied to the soil, particularly olive-mill wastewater, Alfaplus®, Rhizosum Max®, and Kendal Nem®, showed a significant reduction of the P. ramosa infestation of the tomato crop with respect to the untreated control, with a positive effect on the productive parameters