WillR – posted 25 July 2002 17:11
While out knocking around my local sod farm, I noticed the workers were killing crab grass with a dyed chemical that the label said “4D-Amine”.
Can you provide some teaching on this since I know of no other crab grass killer that is safe for St. Augustine grass?
frenchman – posted 25 July 2002 22:25
It is called 2,4-D Amine. It’s a broadleaf weed killer. It will not kill crabgrass. I use 912 herbicide to kill crabgrass, but I don’t know if it’s safe for St. Augustine since I don’t know anything about that type of grass.
seed – posted 27 July 2002 14:39
You are stuck with trying to pull out the crabgrass by hand or pitchfork, and trying to grow in the St. Augustinegrass by mowing high (3-4 inches) and adequate fertilization, about 6 pounds N per thousand square feet per year.
You are right, there is no selective chemical crabgrass killer for use on St. Augustinegrass lawns. (Asulox which was labeled, is now only available for sod farms, and this was a decision of the manufacturer.)
2,4-D (forms including amine and various esters) is not selective for control of crabgrass in St. Augustinegrass. It will have minimal effect on crabgrasses, and depending on the formulation it may kill the St. Augustinegrass. There are some 2,4-D formulations that are labelled for St. Augustine, but they would be for broadleaf control. Check the label, and this should tell what you can do and cannot do, provided it is an herbicide that you bought recently in your state.
Phil
scott – posted 19 February 2004 16:17
try this new product as it will KILL crabgrass without harming your st. augustine www.agralawn.com