Weeds Associated with Cross-Border Traffic, Their Approach and Infestation Rates in Zimbabwe

Weeds carried by different plant pest-pathways in international cross-border traffic are linked to severe biological and biosecurity threats to plant health, animal health, food safety and environmental safety. Regulated quarantine weeds have zero tolerance in pest pathways across borders. This study analyzed 1668 human-aided transboundary plant pest-pathways drawn from 14 ports of entry and a non-official crossing point during the period stretching from 2020 to 2024 at the Plant Quarantine Services Institute Central Laboratory and the National Herbarium and Botanic Gardens Institute. Three regulated weeds that impact plant trade and seed production systems were identified. The weed approach rate was 182 from a global pest rate of 1072. Two weed species (Datura stramonium L and Adenium obesum (Forssk.) Roem. & Schult.) found in association with human-aided cross-border traffic concerns food and feed safety matters. Analysis of variance of the main effect of the pest-pathways categories revealed highly significant differences in weed approach rates (P< 0.001). Weed pests were prevalent in plant–pest-pathways imported for uses other than plant propagation. The Beitbridge and Forbes border ports had the highest volume of human-aided plant pest pathway traffic and were also associated with high weed approach rates into Zimbabwe. Victoria Falls and Robert Gabriel Mugabe International airports were associated with the hitchhiking of plant propagules in passengers’ baggage. It is recommended that weed pests be guarded precisely in grain products and passengers’ baggage by employing baggage scanners and sniffer dogs to aid phytosanitary inspections at ports of entry.