For long term control though, you should apply a pre-emergent in the late fall and early spring which will prevent new crabgrass from coming up next year. If you apply pre-emergent every year, you should not have issues with crabgrass long term. Dimension 2EW is one of our most popular pre-emergents for crabgrass.
Dimension 2EW is one of our most popular pre-emergents for crabgrass as well as many other broadleaf weeds, and it can safely be used on St. Augustine grass. Please check the product label to ensure that it will control the other weeds that you are targeting.
Yes, you will mix the amounts as specified on the label. It does not sound like a lot, but it is enough product to treat the area in at least two gallons of water.
The best time to apply Dimension 2EW Herbicide is after the ground is no longer frozen and before the soil temperatures reach 60 degrees.
Pre-emergents like Dimension 2EW should be used before the weeds germinate in the fall time. We would recommend checking with a local master gardener in your area to give you an exact time. Here is the link:
http://www.csrees.usda.gov/Extension/
Please let us know if you have any additional questions.
We would not recommend Gallery 75 DF, as it's not labeled for Crabgrass or Poa annua. We would recommend to use Dimension 2EW Herbicide, it's labeled to help with pre-emergent control of Crabgrass, Spotted Spurge and Poa Annua, it's also safe to use on Bermudagrass (except on Tifgreen 328 hybrid), Zoysia and Tall Fescue. Dimension 2EW can also be used on landscaped ornamentals.
Centipede is listed as a tolerant grass on the product label. Be sure to read and follow the directions on the Dimension 2EW product label for best results.
Dimension 2EW Herbicide should be applied when the soil temperature is at least 55 degrees Fahrenheit. This is generally done in early to mid March through the beginning of April depending on the temperature.
Dimension 2EW is a pre-emergent herbicide, so it is best applied before soil temperatures reach those that are optimal for the weeds you are targeting. This is generally before soil temperatures reach 55 degrees in the spring. In the fall, you would want to apply before soil temperatures cool to those favorable for these weeds, usually below 70 degrees. We recommend contacting your local Cooperative Extension for the best recommendation on application timing in your area.
After application of Dimension 2EW Herbicide, you can reseed 3-4 months after application. Per label:
Dimension 2EW Herbicide is a pre-emergent herbicide to prevent weeds from germintating so it will not kill existing quackgrass. Unfortunately, there is really nothing that can be done other than spot treating with a Roundup-type product.