Before becoming a dog owner, I was not so concerned about using crabgrass preventer on my lawn. I presumed that if applied the herbicide according to the instructions on the label, everythng would be fine. Although, I still think for the most part that is true, it doesn’t hurt to take a few additional steps to minimize any risk.
What is Crabgrass killer
Most crabgrass preventers are pre-emergent herbicides which are applied to a lawn in the spring before the weed is established. Since the toxicity level of the herbicide is low, use of the chemical is considered safe when applied according to label’s directions. If you fail to control crabgrass in early spring, a post-herbicide can be used to control crabgrass later in the growing season, but it may have to be applied by a professional.
Read the Label
Herbicides sold in the U.S. contain these signal words on the label: Caution, Warning or Danger; they let you know at a glance the danger level of the chemical. Crabgrass preventers are labeled Caution, meaning they have the lowest level of toxins compared to the higher levels found in herbicides labeled Danger. Some chemicals labeled Danger can kill a mammal — like a dog — when less than 1 teaspoon has been consumed.
Keep the Dog In
Preventing a dog from absorbing the herbicide through its skin or by ingesting it is paramount. Direct exposure to a herbicide can be dangerous to a dog and it should be washed off immediately. To prevent contact with recently applied herbicide, keep your dog off the lawn until the grass is dry. Dogs permitted on the grass before it is dry, can absorb the herbicide through their paws — or skin if the roll in the grass — and ingest it by licking their paws or the grass. Since drying time varies by weather conditions and herbicide, read the label and follow the manufacturer’s recommendations.
Two post-emergent herbicides are sometimes used to treat crabgrass: dithiopyr and quinclorac. Dithiopyr can control the weed up to its third leaf stage, but this herbicide currently can only be applied by a professional applicator. Quinclorac is sold in ready-to-use bottles, but it has limited effectiveness on the weed. Quinclorac is labeled Caution, suggesting low toxicity. Dithiopyr is dispersed at rates between Caution and Danger depending on formulation.
The long-term effect of repeated exposure to herbicides is still uncertain. A recent study conducted by Perdue University noted that chemicals used to treat lawns were found in a dog’s urine more than was found in dog’s from untreated lawns. The authors of the study say that if a lawn needs to be treated with a chemical wash the dog’s paws when it enters the house. They also suggest doing the front and back lawns on alternate weeks and, they say, never over-apply the chemical since a dead or dying plant is unable to absorb the excess.
Considerations and Alternatives
If a dog utilizes only a small — or specific — portion of the yard, consider using methods other than crabgrass preventer to control the weed. By not spraying the area where the dog resides any potential health threat is removed. Alternative methods of control include pulling the weed, using a vinegar-based homemade weed killer, pouring boiling water on the crabgrass, or applying corn gluten meal to your lawn twice a year.