Cuscuta reflexa (Dodder weed) is an invasive species in Tanzania, affecting a wide range of crops. To date it has invaded the three main onion growing areas resulting in farmers abandoning their arable land and seeking new uninfected land. In this study weed indices were assessed to monitor the response to various weed management strategies. The study was conducted in the Kilosa district (29° 52' S and 98° 66' E) The experiment was laid out in a randomized complete block design (RCBD) and replicated four times. The responses of the three onion (Red Creole, Russet and Red Bombay) varieties to five weed management plans (Hand hoeing, Hand pulling + rice husk, Oxyfluorfen, anaerobic soil disinfection (ASD) and black polythene much) were assessed. The results show that the various weed management practices have significantly different outcomes (P ≤ 0.01). The dry weight of Cuscuta reflexa Treated with black-coloured plastic mulch decrease by 6.6 g and Oxyfluorfen by 14.4g while anaerobic soil disinfection by 16g, rice husks + hand pulling by 32.8g, and hand hoeing by 52.4g. The dry weight of Cuscuta reflexa decreased across the onion varieties. Red Bombay outperformed other varieties in bulb weight (113.98g) when treated with the rice husks + hand pulling method. However highest yield was obtain in the use of Rice husk + Hand pulling (27.55 tonnes) and the lowest yield recorded on the use of hand hoeing (0.70 tonne).The study shows that the use of Rice husk + Hand pulling would be best substitution of the chemical use since its gives more yield and produce the crop with less residual and easy farmers to adopt.
Keywords: Cuscuta reflexa, black polythene mulch, oxyfluorfen, anaerobic soil disinfection