Bahiagrass (Paspalum notatum) is commonly referred to as highway grass. It’s a tough, drought tolerant, perennial grass that survives in soils with low fertility. Due to its very coarse and open growth habit, bahiagrass is considered a low-quality lawn grass. It is best suited to use as a utility grass for roadsides and erosion control in marginal areas where visual quality is not a high priority.
Native to Brazil, bahiagrass was originally introduced as forage grass for livestock. It forms a deep, extensive root system, with thick rhizomes that grow on the soil surface. Bahiagrass is a prolific seed producing grass. The tall, distinctive v-shaped seed heads appear rapidly throughout the growing season. The coarse stems easily dull lawn mower blades; therefore, it is important to sharpen the blades on a regular basis. Dull lawn mower blades tear the grass and increase susceptibility to diseases.
Although bahiagrass can be difficult to control, good results can be achieved when using selective herbicides in autumn. Most post-emergent herbicides are systemic. This means the chemical is absorbed by the leaves and then sent throughout the plant. Herbicides work in different ways refered to as their mode of action. The mode of action is the process that the herbicide uses from absorption of the chemical to plant death. Most selective grass herbicides are moved to growing points where new shoots, stems, and roots begin their growth. Attacking warm-season, perennial, grassy weeds, as they prepare for winter dormancy, yields greater results than summer herbicide applications. The weeds are unable to produce enough energy through photosynthesis to overcome the damage the herbicides inflict. Emergence and growth are reduced for the following spring when follow-up applications of herbicides can be resumed.
Most perennial weeds require several growing seasons to achieve control. At best, perennial weeds can be suppressed, and their appearance in the landscape greatly reduced. Eradication is not feasible. For a list of selective herbicides to control bahiagrass in your home lawn please see HGIC 2316, Bahiagrass.