The competitiveness of the invasive weed Parthenium hysterophorus with field tomato (Lycopersicum esculentum) in Israel

Crop-weed competition is a significant barrier to successful crop production. Understanding invasive weed competing with field crops is rather difficult, mainly due to the absence of physiological and ecological knowledge, which allows selective and appropriate control of the weed. Parthenium hysterophorus is a worldwide noxious annual weed infesting field crops and orchards. A competition experiment between P. hysterophorus and field tomatoes in containers under controlled conditions resulted in a decrease in tomato biomass production. We found that the presence of P. hysterophorus at all planting ratios in a replacement series caused a significant reduction (~18% to 40%) of tomato shoot biomass m^-2, whereas P. hysterophorus plants gained ~11 to 75 % in shoot biomass m^-2 at all planting ratios with tomato plants. Our results emphasize the need for efficient management of this invasive weed to achieve reasonable yield and allow marketable cropping.