Need help identifying this grass/weed, which is in St. Agustine (one photo shows comparison with a St. Augustine blade). Very thin blade, crawling under/within St. Augustine stolons, and is reddish at base. Forgot to include seedhead, which is roundish ball, and at the juncture of a lowercase "t". In other words, the blade continues up and to the sides of the head. Also, if Atrazine will kill it. Thanks.