Grub damage starts to become evident in around May when there’s increased activity following the feeding program that you started in early spring. It is important to know when to apply grub control in order to prevent damage to your grass.
The best time to apply grub control is between early spring and late summer when there’s increased grub worm activity in your lawn. For grub preventers, apply between June and July just before they hatch while for grub killers, apply the treatment from spring when you see signs of grass damage.
June bugs and European chafers usually lay their eggs in lawns and gardens. As soon as they hatch, they develop into grubworms and start eating grass roots throughout the warm seasons.
You’ll notice signs of dead patches of grass any time from early spring to mid summer when the damage stops due to the grubs having developed into pupae and adults.
So, throughout this life cycle of Japanese beetles and European chafers, what is the best time to treat for grubs with a preventer or a killer?
What’s the Best Time to Apply Grub Control
The best time to apply grub control depends on whether you’re preventing them or killing the ones already damaging your lawn. It is usually best to put down grub preventers in June and July just when the grubs are about to hatch. This will provide the best preventative control of grubs for the next season.
If you want to stop grub damage immediately, the best time to apply grub killer insecticide in your lawn is as soon as you see signs of damage. This is usually any time between early spring to early August when the grub worms are most active eating and damaging grass in your lawn.
But, when is it too early to apply grub control?
When treating your lawn to prevent grub damage for the next season, it would be too early to apply grub preventer on your turf in early spring.
The pesticide will easily disintegrate into the soil and lose its potency by the time the grubs hatch in July through August.
According to the Colorado State University Extension, “insecticides are best used in ways that allow them to be in high concentration in the root zone at the same time eggs are hatching and young white grubs are present.”
When timing is done right, you’ll be able to control about 80 percent of the grubworm infestation in the next season.
For the grub killers, you can stop lawn damage almost immediately especially if you follow the right application guidelines on the label of the pesticide.
What to do after putting down grub control pesticide
You want to get the best effects after applying the pesticide on your lawn. Here are a few tips on what to do after the application:
- Water your lawn immediately after putting down grub control: Most grub killers and preventers come as granular formulations. For them to be effective, water your lawn to at least 1-inch.
- Monitor your lawn for grub worm activity after treating it. After applying a grub killer, you expect eradication to happen from within a few days to a week. If the damage continues, it is likely the grub treatment was not enough or did not work.
Pro tip: Some grub control pesticides such as Bayer Advanced 12 Month Tree & Shrub Insect Control provide long-term control and can be applied almost any time of the season. It can kill adult beetles and reduce their population in your yard.
Do you need to apply grub control every year?
Did you find grubs in your lawn last spring? Then you may need to apply a grub preventer for lawns.
You do not need to apply grub control every year successively unless you see grub damage. If you’ve been treating your lawn with a grub preventer and killer for a few years in a row, it may be time to stop until you see the signs of grubs and European chafers again.
Grub preventers help control grubs for every next season. You cannot apply a grub preventer to kill grubs that are already damaging your lawn. If you’re applying a grub preventer, it will not get rid of grubs that may be present in your lawn from mid-October through the middle of May.
For that, you need to apply a grub killer such as GrubEx. Otherwise, you need to apply the insecticide between May and July to prevent infestation for the next season by killing and harming the development of the next generation of grub worms in your lawn.
In healthy turfs, a few grubs should not be a problem and you may not need to apply insecticide every other year. You only need to start a grub control treatment when you see signs of damage.
If you feed your lawn properly, your grass can support about 5 grubs per square foot of turf without any visible damage. Your lawn will still look green and healthy because the damage from their feeding activity will be very minimal.
What to Look for in Grub Preventers
Most homeowners mean to kill grubs when they see signs of infestation. However, the best way to control their damage for the long-term is by putting down a preventer.
A good preventer will contain any one of these active ingredients:
The reason why you want to look for these ingredients is that they are very good at killing grubs at a tender age, usually as soon as they hatch.
How often should you apply grub control?
Grub treatments are effective when applied at the right time. In some cases, you may need to apply the pesticide two or three seasons in a row to completely eradicate grubs in your lawn.
In most cases though, you’ll only need to apply grub control twice in a season -- the first one being a grub killer when you see signs of infestation and the second one being a grub preventer around June and July to stop their cycle.
Can GrubEx be applied in the fall?
The best time to apply GrubEx is early spring through mid-summer when grub activity in lawns in heightened. Fall might not be a very good time to put down grub control.
As temperatures continue to drop with winter approaching, grubs dig down approximately 4-8 inches into the soil and lay there until temperatures start to rise again.
You may not get much success controlling lawn grubs and European chafers if you apply GrubEx in October and November, or the duration of fall because it might be too late to treat for grubs.
- K-State Extension: Grub Control: How to get rid of grubs in the lawn
- Colorado State University Extension: Billbugs and White Grubs: Control in Home Lawns – 5.516
- The Connecticut Agricultural Experiment Station: Managing White Grubs in Home Lawns
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