How to Control Dollar Weed in St Augustine Grass Lawn

The waxy glossy green leaves of dollar weed present themselves just above and horizontal to the mowing plane of the lawn – making dollar weed one of the most visible and noxious weeds in a St Augustine grass lawn.

But that highly visible leaf is only a small part of the problem because dollar weed lives primarily below ground - about 90% of the plant is below ground. So, killing the leaf does little to control the plant!

Controlling Dollar Weed is Difficult

Herbicides used to control dollar weed in lawns such as Scotts Bonus S Weed and Feed and Ortho Weed-B-Gon are ineffective and potential lawn killers if not applied correctly. The reason products such as Scotts Bonus S Weed and Feed and Ortho Weed-B-Gon fail to work are twofold: First the products are weak and watered down formulations and second the below ground parts of dollar weed are resistant to herbicides and capable of repopulating a lawn in a short time. In other words these watered down consumer products simply knock the tops off and leave the below ground roots and stems unharmed.

Using Atrazine or Weed n Feed To Kill Dollar Weed

Scotts Bonus S Weed and Feed uses atrazine, a great herbicide for dollar weed control if used properly but has two major problems: regulations have reduced rates to below effective levels and if atrazine is applied when temperatures are above 85⁰F it will kill a St Augustine Lawn. So you can only apply atrazine during the winter and spring and the dosage - set by law – is so low that the dollar weed often escapes the treatment. Scotts Bonus S Weed and Feed is more “smoke and mirrors” than true dollar weed control – the fertilizer turns the St Augustine brilliant green so the lawn “appears” to have fewer weeds.

Using 2,4D Herbicides to Control Dollar Weed in St Augustine

St Augustine grass is very sensitive to 2,4D compounds used in herbicides like Ortho Weed-B-Gon. These products are listed as “spot” treatments are not intended to be broadcast over the entire lawn. They work great for one or two dollar weeds scattered in a lawn. However rarely does anyone have just a “weed or two” to treat and treating the entire lawn will result in a dead lawn.

Over Watering Causes Dollar Weed is a Myth

Dollar weed causes dollar weed – not water. Nearly 90% of the plant lies below ground and out of sight. The plant forms a mass of underground stems and roots capable of withstanding drought or floods. Each underground stem is capable repopulating your lawn when conditions permit. So cutting back on the water only stresses your St Augustine grass lawn and does not stop dollar weed from growing in your lawn.

How to Control Dollar Weed in St Augustine Grass Lawn

Persistency, consistency and Manor herbicide are my best methods and tools to control dollar weed. A persistent “never give up attitude” is required when the dollar weed seems to reappear after each application. Repetitive consistent effort is the only way to defeat the below ground roots and stems and keep them from repopulating your lawn. And with St Augustine grass the safest most effective herbicide is Manor – it is expensive, it is slow, it is difficult to apply but is an effective herbicide on dollar weed and safe to use on St Augustine grass.

Best Method for Controlling Dollar Weed In St Augustine

If you want to control dollar weed it will take an investment of persistent, consistent effort and money using Manor herbicide. The alternative is to hire a pro to spray your lawn on a regular schedule with Manor. Treating the lawn every 8 weeks is minimum and once a month will give very good results – keeping dollar weed out of sight and possibly eliminating it from your lawn, but not your neighbors.