Nuisibility of Leucas aspera (Willd.) Link (Lamiaceae) in Pearl Millet Culture [Pennisetum glaucum (L.) R. Br. (Poaceae)] in Eastern South East Niger

Weed competition is a major obstacle to millet cultivation [Pennisetum glaucum (L.) R. Br. (Poaceae)]. The present study was conducted in the south-east of Niger to determine the density of Leucas aspera (Willd.) Link (Lamiaceae) likely to influence millet production, in order to help farmers define technical itineraries for controlling this species. The experimental set-up is a randomized complete block design with four replications and 24 elementary plots. Five types of density (1, 2, 3, 7 and 10 plants) of Leucas aspera around the millet plot were tested. Data collected were mean height, number of plants and plot weight of millet. A one-factor analysis of variance (ANOVA) and Duncan's test at the 5% threshold were used to compare mean heights and yields with the control. Results showed that tolerant density can be estimated at 2 plants/m² of Leucas aspera. Above this critical value, early competition occurs between weed and millet plants from the third week onwards. The lower the density of Leucas aspera, the higher the yield. The average reduction in millet yield from Leucas aspera was 81.95%, with a minimum of 96.55% for the treatment of one Leucas aspera plant and a maximum of 99.66% for the treatment of 10 Leucas aspera plants. These results could help improve weed management in millet cultivation.