General Impact
Bidens pilosa is a problematic species for many reasons throughought its range. A troublesome weed to at least 30 crops in over 40 countries, B. pilosa is known to significanly reduce crop yields. One study found that dry bean, Phaseolus vulgaris, harvests were reduced by 48% in Uganda and 18-48% in Peru due to impacts by B. pilosa. It forms dense stands that can out compete, out grow, and eliminate crop and native vegetation, specifically the lower vegetative strata, over large areas. B. pilosa prevents the regeneration of these plants as well, given its allelopathic properties. Leaf and root extracts are known to significantly suppress germination and seedling growth of many plants and are believed to remain active throughout decomposition. Furthermore, B. pilosa grows three times faster than similar plant species. All of these porperties render it a quite formidable competitor.
Its thick stands impede access to roads, trails, and recreational areas, are a nuisance to travelers and tourists, and inflict damage to pavements and walls. Its burrs are a nuisance to people, as well as, sheep and other fleece producing livestock. The burrs are also a troublesome seed contaminent as they are difficult to seperate from grain. The roots, leaves, and flowers are strongly phytotoxic and a poisonous, if unprepared, and capable of inflicting injury. Bidens pilosa is also a host and vector to harmful parasites Root knot nematodes (Meloidogyne sp.) and Tomato spooted wilt virus (Schlerotinia sclerotiorum) (DPI, 2008; Mvere, 2004).
No Impact information recorded for Bidens pilosa
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