EFFICACY OF HERBICIDES AND SHADING METHODS TO CONTROL INVASIVE SPHAGNETICOLA TRILOBATA (L.) PRUSKI

Sphagneticola trilobata (L.) Pruski is one of the most noxious invasive plant species, posing a serious threat to native biodiversity. This species has been invading large areas of Bangladesh for the last two decades. The study investigated the efficacy of herbicides and shading treatments during winter and monsoon to find an effective control method for S. trilobata. Both surface-inhabiting (Glyphosate) and root-inhabiting (Paraquat) herbicides were applied for six months in five different combinations (100% Glyphosate, 75% Glyphosate + 25% Paraquat, 50% Glyphosate + 50% Paraquat, 25% Glyphosate + 75% Paraquat, and 100% Paraquat) and the percentage coverage was measured for each experimental plot. Results from the study showed that all shading and chemical combinations of Glyphosate and Paraquat significantly reduced the percentage coverage of S. trilobata in each experimental plot (p < 0.05). However, the shading and Paraquat-dominated combinations reduced the coverage slowly compared to the Glyphosate-dominated ones. Among five different combinations, Paraquat-dominated herbicides were less effective in controlling the species. On the other hand, the Glyphosate-dominated combinations completely eradicated the species within a week but increased thereafter. Meanwhile, the seasonal variation was found to be highly significant (p < 0.0001) among treatments, and a significant reduction was observed in winter compared to the monsoon. The results of this study highlighted that the Glyphosate-dominated combinations were the fastest, while the Paraquat-dominated combinations and shading were slower control methods.