Weed flora in irrigated alfalfa (Medicago sativa L.) intercropped with olive trees (Olea europaea L.) along the Moulouya wadi, eastern Morocco

A study of the weed flora was conducted in 22 irrigated alfalfa (Medicago sativa L.) fields along the Moulouya wadi (eastern Morocco) (arid bioclimate), during the 2021 and 2022 growing seasons. Fields were surveyed once in October 2021 or April 2022, with complementary collects from 2022 to 2023, to identify taxa which were not at the right phenological stage during our two main field surveys. Field sizes varied from 500 to 12,400 m². No herbicides were used in any field, and alfalfa and weeds were cut for hay. Alfalfa was inter-cropped with olive trees in 77% of the surveyed fields. In total, 16 cultivated species and 205 weed taxa that belong to 39 plant families were recorded. The weed flora was dominated by broad-leaved weeds, representing (158 taxa, 77% of weeds). The annual weeds represented 110 taxa (54%). The number of weed taxa per field varied from 19 to 61, with an average of 41. Weeds that had a high cover (between 5 to 25%) were Cynodon dactylon (L.) Pers., Echinochloa colona (L.) Link, Plantago lagopus L., Setaria adhaerens (Forssk.) Chiov., and Setaria pumila (Poir.) Roem. & Schult. Weeds poisonous to livestock were Datura stramonium L., Euphorbia helioscopia L., Peganum harmala L., Solanum elaeagnifolium Cav., Solanum villosum Mill., and Sorghum halepense (L.) Pers. Weed cover was in general <10% which suggested that cutting weedy alfalfa for hay is effective for weed management.