How to Control Dollar Weed in St Augustine Turf Grass Lawn (2023)

The Problem with Dollar Weed

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!

The good side of dollar weed is that it thrives in the same culture as does St Augustine turf. If you have a dollar weed problem, chances are lurking just below the dollar weed are the remnants of a St Augustine lawn. Then, if and when you control the dollar weed, you will have a lush green lawn.

Controlling Dollar Weed is Difficult with Home Improvement Store Herbicides

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 applied incorrectly. The reason products such as Scotts Bonus S Weed and Feed and Ortho Weed-B-Gon fail to work are twofold:

1. The home improvement store products are weak watered down formulations
2. The below-ground parts of dollar weed are resistant to herbicides and capable of repopulating a lawn in a very 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 use atrazine, a great herbicide for dollar weed control if used properly but have two major problems:

1. Regulations have reduced rates to below effective levels
2. 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 actual dollar weed control – the fertilizer turns the St Augustine brilliant green so the lawn “appears” to have fewer weeds.

Lawn Myth - Over Watering Causes Dollar Weed

Dollar weed causes dollar weed – not water. Reducing the water only stresses your St Augustine grass lawn and does not stop dollar weed from growing in your lawn. Nearly 90% of the plant lies below ground and out of sight. Each underground stem is capable of repopulating your lawn when conditions permit – as when a lawn is stressed from under watering. Stressing your lawn by cutting back the water allows for more dollar weed not less!

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

St Augustine turfgrass - especially Floratam – the most widely used St Augustine turf grass for lawns in Pinellas County - is very sensitive to 2,4D compounds used in herbicides like Ortho Weed-B-Gon. These products are listed as “spot” treatments and 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 often treating the entire lawn will result in a dead lawn.

How to Control Dollar Weed in St Augustine Grass Lawn

Best Method for Controlling Dollar Weed in St Augustine

If you want to control dollar weed it will take an investment of persistent and consistent effort using Metsulfuron Methyl herbicide. Treating the lawn every 8 weeks is a minimum and once a month will give very good results.

The alternative is to hire a good lawn spray company. APL Pest Control will include fertilizer, insecticides, and herbicides with Metsulfuron Methyl as part of the 6 basic services per year to keep your lawn healthy and thriving.

Related Articles