Assessment of weed species composition and diversity in tomato (Solanum lycopersicum L.) farms in Ethiopia

Background: Weeds compete for vital nutrients and water with the tomato plants and serve as an alternative host for other pests. Although there is limited information on the weed species composition in major tomato-growing areas in Ethiopia, this study was conducted to identify the economically important weed species in tomato fields in the East Wollega, Shewa, West Shewa, Arsi, and Sidama zones. Methods: The weed flora assessment was conducted in major tomato growing zones of the country, such as East Shewa, Wollega, West Shewa, Arsi, and Sidama zones, in the 2018–2019 cropping season during the off-season. In each tomato field a 1 m x 1 m quadrat was thrown following an inverted X pattern, and weed species were recorded. Weed species composition was calculated using standard formulas. Results: The results revealed that 63 weed species under 23 families were identified at the surveyed locations. Portulaca oleracea was the most abundant and dominant, with 50% of the dominance value. Weed frequency values ranged from 0.06 to 72% in the studied areas. The weed  similarity index was also different among the surveyed locations. The results of farmers perceptions on weed management in tomato fields showed that 61% of respondents practiced hoeing followed by hand weeding, and Tuta absoluta was the most significant constraint to tomato production in the surveyed areas. Conclusions: This assessment showed that there are differences in the composition and distribution of weed species in tomato fields in Ethiopia, which aid in predicting the population dynamics of weed flora. Farmers perceptions of weed management practices in tomato fields were also different. Therefore, different environmentally friendly weed management options such as good crop husbandry, biological control, and integrated management should be designed to increase tomato production and productivity.