Grub control

Asked May 22, 2018, 11:41 PM EDT

Greetings! My 10,000 sf lawn has turned into Stalag 13 with so many mole tunnels. I believe the lawn requires Milky Spore treatment to stop the grubs? Is this correct? If so I have a few questions I hope you can answer: 1) With 10,000 sf of grass would you recommend the powder or granule, and why? The granules are getting poor reviews. 2) Since Milky Spore (MS) takes 2-3 years to become fully effective can I put down a product like Bayer 24 hour Grub Killer Plus to take care of the problem until the MS spreads and becomes effective? 3) Will the Bayer product interfere with the MS spores reproducing and spreading? 4) If I cannot put down both at the same time, what is the time frame to wait after I spread the Bayer product before I can apply the MS? 5) St. Gabriels Organics MS appears to be the most popular product available. Do you recommend this, or is there a better product? Thank you in advance,

Charles County Maryland

1 Response

We only recommend a grub control if grubs are feeding on your turfgrass roots. Moles feed on a variety of soil invertebrate such as earthworms not just grubs. They are more a nuisance in the spring and fall when soil moisture levels are higher and prey are closer to the surface of the soil. Activity often stops on its own so in many cases control for moles is not needed. Tamp down raised tunnels with your foot whenever they appear and the ground is not soggy. Some reseeding may be required.

The application of lawn insecticides to kill grubs is no longer recommended if wildlife is feeding on soil insects. Grub control products should only be applied to lawns that have experienced a grub problem and grubs are feeding on turfgrass roots.

Here are some reasons to apply a grub control. Make sure you have a grub problem. Reasons include past history of grubs, if you have a sprinkler system that keeps the soil moist for egg laying, and if we have weather conditions like wet summers and lush lawns while the adult beetles are active in June.
The turf can be rolled back from the soil like a rug this is usually in late summer to early fall. Look for grubs in the upper soil surface, you may need to dig with a trowel. If the grub count exceeds 6-8 per square foot, you may want to consider treating for grubs.

In general, adult egg laying begins in July and root feeding begins in August. Grub controls are applied as a preventative (time frame is mid June through August). Look for a season long grub control that contains the active ingredient Chlorantraniliprole. This product is more environmentally friendly. See our publication on japanese beetles for more information

We have not recommended milky spore for grub control for many years. University research has indicated it performs poorly. The other downside is that it only controls Japanese beetle grubs and there are many other types of grubs in Maryland lawns.
The Bayer 24 hour Grub Killer Plus is a broad spectrum insecticide that kills beneficials as well as pest insects and not recommended.