Test of restoration of guineo-sudanian pastures invaded by Chromolaena odorata and Hyptis suaveolens in Benin

Abstract

Chromolaena odorata and Hyptis suaveolens as invading pastures in Benin and non‐palatable, are indicators for degraded grazinglands and major handicap to the pasture management in subequatorial Bénin. Improving grassland phytomass productivities and nutrient value is important for successful herbivore breeding. In an attempt to rehabilitate pastures invaded by these species, we tested the use of the selective herbicide, Garlon 2E from CAMN Ste Armel (France) containing trichlopyr (240 g/l) (1E ＝ Trichlopyr 120g / l in form of salt of triethylamineand) as the active ingredient. Single application of 1L of Garlon 2E/100 l of H2O per ha eliminated Chromolaena odorata where ever its pre‐treatment cover rate was less than 15%; (ii) ２ applications every 30 days were effective where cover rate ranged from 15 to 35%; (iii) a concentrated application (1L/25 L H2O per ha) followed by an economical application where cover rate ranged from 35 to 80% ; ( iv) ２ applications every 45 days are effective where cover rate ranged from 80 to 100%. Applying the economic amount consecutively to the concentrated one after 30 days could be suitable. For pastures mostly invaded by C. odorata (weed cover ＞80%), 2 consecutive applications of concentrated amounts every 45 days appeared to be suitable. For H . suaveolens, results were strong at 1L of Garlon 2E by 50 water L per ha. Two consecutive applications every 45 days are suitable. A consistent control requires replication in the 2nd year. Consecutive applications every 30 days might be suitable. Otherwise, H . suaveolens controls beans crops.