Assessment of spread of noxious Kongwa weed in Tanzania, using pathway risk analysis.
The noxious Kongwa weed (Astripomoea hyoscyamoides VatkeVerdc.) has been reported to cause enormous damage to crops and pastures in various parts of Tanzania, particularly Kongwa District of Tanzania. This paper assesses spread risk of potential pathways for the entry and spread of it in Kongwa District. The research progressed in two stageswith the first stage comprising a review of relevant local and international literature on the means of weed spread. Secondly, a household survey using a semi-structured questionnaire was conducted in Kongwa district to collect data on various land use practices that are associated with the spreading of the weed. Risk assessment framework containing six criteria was applied to the identified potential pathways. Pathway risk for each pathway was evaluated and assigned an intensity rating score through an analysis of the interviewee answers using Statistical Package for the Social Sciences (SPSS) software version 26. Results showed that, the most high-risk pathways were livestock movements and stock fodder transportation (81%) and agricultural produce and inputs (77%) which was attributed to the existing land use type in Kongwa. The medium risk pathways were farming tools, equipment, machines, footwear and clothing (75%) and water dispersal (56%). The low-risk pathways were wind dispersal (44%), construction activities (43%), escape from research sites (30%), ornamental plant trade (28%), tourism (25%) and introduction via exotic plant species (20%). Based on these findings, government and other stakeholders are advised to allocate weed preventive resources in the order of the threat level posed by a particular pathway.