When it comes to grubs, timing is everything. Right now, as John Grisham might say, is a time to kill.
The little white ‘C’ shaped insects you sometimes find while digging in your yard or flowerbeds are the immature stage of several types of beetles. Adult beetles lay their eggs in the ground during the summer. As soon as the eggs hatch, the grubs that emerge begin feeding on roots, thatch, and other organic material. This becomes a problem in regard to our lawns, because typically after a few months of drought stress and scorching heat, sod isn’t in its best condition to begin with. Little grubs munching away at the roots can lead to brown dead spots and areas of spongy turf that can be easily rutted or damaged.
Once the weather gets colder, the grubs will dig down up to 8 inches to overwinter. At this point, feeding has stopped, and they are too deep for insecticides to be effective. This means that your window for successfully ridding your lawn of grubs is now through October- depending on how quickly it cools off.
So then the question becomes, do you have a grub problem? The easiest way to test, if you are concerned that they might be the culprits in current lawn damage, is to dig up a small section of grass and look under it. A 1ft x 1ft section should do the trick. Some grubs are present in every yard and aren’t an immediate cause for concern, but if you count more than 10-15 in that square foot area, you may want to consider some form of treatment.
For organic gardeners, there are nematodes that can be purchased online and shipped directly to your house for biological grub control. (They can also be special ordered via Enchanted- come talk to me if you’re interested) When ordering nematodes, make sure that you get a variety labeled specifically for grubs. They also sell ones that target fleas and other pests…but that’s another blog.
Chemical control methods for grubs include preventative treatments and curative treatments. A curative treatment is best for this time of year if grubs are found to be present in large numbers and are causing damage. I tend to caution against preventative treatments unless you live on the 18th hole of a golf course, have suffered significant grub damage in past years, or have had a huge population of beetles honeymooning on your lawn in the last year. With preventative treatments, you are applying insecticide before you even know if you have a problem. Since only a small percentage of lawns actually need treatment annually, you’re probably spending money and applying chemicals unnecessarily. I know far too many people who have the annual shopping list of nasty chemicals that they pick up from the store to spread around their homes in their lawns just because they think that’s the right thing to do as a homeowner. Preventative grub killer is a good example – costly and mostly unnecessary. If you don’t have a problem in your lawn, skip that stuff!
If you do have a problem, come see us at Enchanted. We have stocked several curative insecticides that will rid your lawn of grubs. My recommendation would be to use an insecticide containing the active ingredient Carbaryl. Some recent research conducted by several university studies suggests that products containing only the active ingredients Bifenthrin or Permethrin may not be as effective when treating grubs due to their tendency to bind with organic matter in the environment, making it difficult to penetrate down to the layer where the grubs are feeding. Follow the directions on the label of your product of choice and be sure to irrigate with half an inch of water immediately after application. Mowing right before treatment also helps the insecticide reach the soil more quickly and cuts off any flowers on weeds that might be blooming and could introduce toxins to local bees searching for nectar.
Come visit us for more information on application rates, or if you have any additional questions- we’ll be glad to help!