Help Me: I Sprayed Weed Killer on My Yard and Now I Have Brown Patches

Herbicide Injury Symptoms

• The symptoms of herbicide injury mirror those of some other common plant ailments; just because you have used an herbicide on or near your lawn prior to the lawn's breaking out in brown patches does not necessarily mean that one caused the other. Of course, injury symptoms depend in large part on the herbicide chemical used and the species of weed being targeted, but some common symptoms of herbicide injury include flattened, twisted or corkscrew-shaped leaves, and grass blades that may also take on an irregular shape, along with turning brown. If you are unable to find any other potential causes of brown lawn spots and if you recognize any of these other attendant symptoms of herbicide damage, the chances are good that your lawn is suffering from herbicide injury.

Treating an Injured Lawn

• The most commonly recommended method for treating an herbicide-injured lawn is actually to do nothing at all. So long as the grass is relatively healthy and vigorous and was not exposed to excessive amounts of the herbicide, it should outgrow the damage. Monitor the grass through the growing season and check to see if new, healthy growth is taking the place of the browned and damaged areas. If it does not, the grass may have been exposed to a high enough dose of herbicide that it has died and will need to be replanted. If new growth does appear healthy, simply continue normal irrigation and cultural management practices to make sure the lawn stays sufficiently healthy to survive the herbicide damage.

Preventing Future Injury

• The most important measure any homeowner can take, when faced with an herbicide-injured lawn, is to know what caused the injury in the first place to avoid future problems. Always follow the manufacturer's label instructions meticulously; misapplication of herbicides is the leading cause of herbicide injury on any plant. Make sure to only buy herbicide formulations that are rated as safe for use on and around the specific species of grass you are growing. If the herbicide you used is rated for use on your grass species, consider using another brand or chemical formulation instead and apply the new herbicide on an inconspicuous part of the lawn to test for possible injury.

Other Considerations

• Cultural practices can also offer weed control so effective that you may not need to turn to the use of herbicides to keep weeds off of your lawn. Weeds are competitive plants, so anything you can do to help your grass win the competition for nutrients, water and sunlight will help choke out the weeds from your lawn. Should weeds still break out on your lawn, natural control measures, such as hand-pulling, are often all that is necessary to control the outbreak. Following these natural and cultural control approaches can preclude the need to use any herbicides at all, avoiding the possibility of herbicide injury to your grass.