According to Texas A&M Extension, south Texas lawns should be treated with pre-emergent herbicides before annual weeds, such as crabgrass, emerge in the spring. Perennial weeds, such as sedges, should be treated with post-emergent herbicides during their active growing period.
About this Author
Aileen Clarkson has been an award-winning editor and reporter for more than 20 years, earning three awards from the Society of Professional Journalists. She has worked for several newspapers, including "The Washington Post" and "The Charlotte Observer." Clarkson earned a Bachelor of Arts in journalism from the University of Florida.